Recombinant Borrelia burgdorferi DNA translocase FtsK (ftsK)

What is the primary function of DNA translocase FtsK in Borrelia burgdorferi?

FtsK in Borrelia burgdorferi functions as a DNA translocase that plays a critical role in chromosome segregation during cell division. As observed in transcriptional studies, FtsK expression shows notable sensitivity to regulatory proteins such as DnaA, with a documented 2-fold decline in FtsK transcript levels in conditional dnaA mutants . This DNA motor protein facilitates the final stages of chromosome segregation by translocating DNA to ensure complete chromosome partitioning before septum closure. Unlike the better-characterized FtsK in model organisms like E. coli, B. burgdorferi FtsK operates within the unique cellular architecture of this spirochete, potentially coordinating with the distinctive cell division machinery of this organism.

What regulatory elements control FtsK expression in B. burgdorferi?

FtsK expression in B. burgdorferi appears to be regulated as part of a complex network involving the DNA replication initiator protein DnaA. Transcriptional analyses have revealed that FtsK transcript levels decline approximately 2-fold in conditional dnaA mutants , indicating that DnaA positively influences FtsK expression. This regulatory relationship suggests coordination between DNA replication initiation and chromosome segregation processes in B. burgdorferi. Other potential regulatory elements may include transcription factors responsive to cell cycle progression and environmental stresses encountered during the pathogen's complex life cycle between tick vectors and mammalian hosts. The cell division gene cluster organization in B. burgdorferi suggests potential co-regulation with other division proteins, though the specific promoter elements and transcriptional regulators remain to be fully characterized.

What are the most effective methods for expressing and purifying recombinant B. burgdorferi FtsK?

For successful expression and purification of recombinant B. burgdorferi FtsK, a multifaceted approach is recommended:

• Expression system optimization: E. coli BL21(DE3) strains with rare codon supplements are generally preferred due to codon usage differences between E. coli and B. burgdorferi. Expression at lower temperatures (16-18°C) after induction improves solubility.

• Construct design considerations:

  • Full-length constructs including the N-terminal membrane domain typically show poor solubility

  • The C-terminal motor domain (approximately 500 amino acids) expresses more reliably

  • Fusion tags such as His6, MBP, or SUMO enhance solubility and facilitate purification

• Purification protocol:

  • Initial capture via affinity chromatography (Ni-NTA for His-tagged constructs)

  • Intermediate purification using ion exchange chromatography

  • Final polishing via size exclusion chromatography to ensure homogeneity

  • Buffer optimization containing 5-10% glycerol and 1-5 mM DTT improves stability

• Activity verification: Post-purification, ATPase activity assays using colorimetric phosphate detection provide essential functional validation before proceeding to more complex DNA translocation experiments.

The challenge of membrane protein solubility can be addressed by using detergent screens to identify optimal solubilization conditions or by focusing on the soluble C-terminal domain for initial characterization.

What genetic manipulation techniques are most suitable for studying FtsK function in B. burgdorferi?

The most effective genetic approaches for investigating FtsK function in B. burgdorferi include:

• CRISPR interference (CRISPRi): This technique has proven highly effective for gene repression in B. burgdorferi, achieving at least 95% repression efficiency for various target genes . For FtsK studies, CRISPRi offers the advantage of controlled and tunable repression, allowing observation of phenotypes before lethal effects manifest. Various CRISPRi template constructs with different basal and induced dcas9 expression levels provide flexibility for experimental design .

• Conditional knockdown systems: Given the likely essential nature of FtsK, inducible promoter systems permit temporal control of expression. IPTG-inducible systems have been successfully employed in B. burgdorferi, as demonstrated with other essential genes like ftsI .

• Fluorescent protein tagging: C-terminal fusions with fluorescent proteins like mScarlet or superfolder GFP allow visualization of FtsK localization dynamics during the cell cycle without disrupting the membrane-spanning N-terminal domain.

• Site-directed mutagenesis: Targeted modifications to key functional motifs in FtsK, particularly in the Walker A and B motifs of the ATPase domain, provide insights into structure-function relationships.

What imaging techniques best capture FtsK localization and dynamics during B. burgdorferi cell division?

Optimized imaging approaches for studying FtsK dynamics in B. burgdorferi include:

• High-resolution fluorescence microscopy: Super-resolution techniques like Structured Illumination Microscopy (SIM) or Stochastic Optical Reconstruction Microscopy (STORM) overcome the diffraction limit, allowing visualization of FtsK localization at the division septum with precision below 50 nm. These techniques are particularly valuable given B. burgdorferi's narrow cell diameter (0.2-0.3 μm).

• Time-lapse microscopy: Continuous imaging of living B. burgdorferi cells expressing fluorescently-tagged FtsK provides crucial temporal information about protein recruitment and mobility during the cell division process. Custom microfluidic devices that immobilize the highly motile spirochetes without affecting viability are essential for extended imaging sessions.

• Cryo-electron tomography (cryo-ET): This technique has proven invaluable for studying B. burgdorferi ultrastructure, revealing detailed flagellar structures and cell division sites . For FtsK studies, cryo-ET offers nanometer-scale resolution of the division apparatus within the native cellular context, especially when combined with immunogold labeling to specifically identify FtsK.

• FRAP (Fluorescence Recovery After Photobleaching): This approach measures the kinetics of FtsK movement at the division site, providing insights into whether FtsK remains stably associated with the division machinery or undergoes dynamic exchange.

The helical morphology and motility of B. burgdorferi present significant imaging challenges that can be addressed through careful sample preparation, including the use of methylcellulose or low-concentration agarose to restrict movement without distorting cellular architecture.

How does FtsK activity correlate with cell morphology changes in B. burgdorferi?

FtsK activity and cell morphology in B. burgdorferi appear intricately connected based on several lines of evidence:

• Cell division coordination: When FtsI, another cell division protein, is depleted in B. burgdorferi, cells exhibit dramatic filamentation, growing to lengths almost five times the average cell length (up to 100 μm compared to normal ~20 μm) . As a key component of the divisome, FtsK likely coordinates with FtsI and other division proteins, with disruption of this coordination manifesting as morphological abnormalities.

• Regulatory network influences: The observation that DnaA modulates FtsK expression (2-fold decrease in transcript levels in dnaA mutants) suggests that proper cell morphology depends on coordinated expression of cell cycle proteins, including FtsK.

• Chromosome segregation effects: Incomplete chromosome segregation due to compromised FtsK activity can prevent proper septum formation and cell separation. This connection is particularly significant in B. burgdorferi, which has a unique genome consisting of a linear chromosome and numerous plasmids that must be correctly partitioned.

• Morphological plasticity during the enzootic cycle: B. burgdorferi undergoes morphological adaptations during transitions between tick vectors and mammalian hosts. FtsK activity may be regulated differentially during these transitions to accommodate changing replication and division requirements.

The distinctive spiral morphology of B. burgdorferi depends on proper flagellar assembly and peptidoglycan synthesis. While FtsK primarily functions in chromosome segregation, its activity must be coordinated with these morphology-determining processes to maintain cellular integrity during division.

What is the relationship between FtsK and the flagellar assembly process in B. burgdorferi?

The relationship between FtsK and flagellar assembly in B. burgdorferi represents a fascinating intersection of chromosome segregation and motility functions:

• Coordinated gene regulation: Both FtsK and flagellar genes show responsiveness to global regulators like DnaA. While FtsK transcripts decline 2-fold in dnaA mutants, multiple flagellar genes including fliQ, fliR, flgD, flgV, and flgA are also impacted when dnaA is knocked down . This suggests shared regulatory networks coordinating division and motility.

• Spatial coordination requirements: B. burgdorferi's periplasmic flagella are anchored near cell poles and extend toward midcell where they overlap . This arrangement requires precise spatial coordination with the cell division machinery, including FtsK, to ensure proper flagellar inheritance during division.

• FlgV as a connecting element: Recent research has identified FlgV as a structural flagellar component that modulates flagellar assembly in B. burgdorferi. Strains lacking flgV produce fewer and shorter flagellar filaments and show defects in both cell division and motility . This dual impact suggests potential mechanistic links between the chromosome segregation machinery (including FtsK) and the flagellar apparatus.

• Temporal coordination: Both cell division (involving FtsK) and flagellar assembly must be temporally coordinated during the cell cycle. Disruptions in this coordination, such as through CRISPRi-mediated depletion of division proteins, lead to aberrant morphologies and motility defects.

The periplasmic location of B. burgdorferi flagella creates unique spatial constraints that necessitate precise coordination between chromosome segregation, septum formation, and flagellar inheritance. FtsK likely plays a key role in ensuring that these processes proceed in the correct sequence.

How does FtsK function change during different phases of the B. burgdorferi life cycle?

FtsK function in B. burgdorferi exhibits important adaptations across different phases of its complex life cycle between tick vectors and mammalian hosts:

• During mammalian infection:

  • FtsK activity likely increases during the early dissemination phase when rapid multiplication is necessary for establishing infection

  • Cell division processes, including FtsK-mediated chromosome segregation, appear particularly crucial during the infection and dissemination phases in mice, as suggested by studies with motility-deficient strains

  • The host environment's temperature (37°C) and nutrient availability influence cell division rates and potentially FtsK expression patterns

• During tick colonization:

  • In unfed ticks, B. burgdorferi enters a relatively dormant state with reduced replication, potentially downregulating FtsK activity

  • During the blood meal and subsequent tick midgut colonization, rapid replication resumes, requiring upregulation of division machinery including FtsK

  • Environmental transitions, including temperature shifts and nutrient changes, likely trigger regulatory cascades affecting FtsK expression

• Transmission phases:

  • The transition between hosts represents a critical period requiring coordinated gene expression changes

  • FtsK function may be particularly important during these transitions to ensure proper chromosome partitioning as replication rates change

  • The potential coordination between FtsK and virulence factor expression during transmission remains an important area for investigation

While specific data on FtsK expression across these phases remains limited, the pattern observed with other essential genes suggests a coordinated regulation of chromosome segregation machinery in response to environmental cues encountered during the enzootic cycle.

What are the mechanisms of FtsK-mediated DNA recognition and translocation specificity in B. burgdorferi?

The mechanisms underlying FtsK-mediated DNA recognition and translocation specificity in B. burgdorferi involve several specialized adaptations:

• DNA sequence recognition elements:

  • While conventional bacterial FtsK proteins recognize KOPS (FtsK-Orienting Polar Sequences), B. burgdorferi may utilize modified recognition sequences adapted to its unusual genome architecture

  • The linear chromosome of B. burgdorferi, with distinct telomeric structures, likely requires specialized DNA recognition by FtsK to ensure proper segregation

  • Bioinformatic analyses suggest potential B. burgdorferi-specific DNA motifs that may guide FtsK directionality, though these require experimental verification

• Domain-specific functions:

  • The γ-domain of FtsK typically mediates sequence-specific DNA recognition

  • The α and β domains form the ATPase motor that powers DNA translocation

  • Structure-function analyses using recombinant domain constructs could clarify which regions determine B. burgdorferi-specific activity

• Plasmid segregation coordination:

  • B. burgdorferi contains numerous essential plasmids that must be properly segregated

  • The mechanism by which FtsK might contribute to plasmid partitioning, either directly or through interactions with plasmid-specific segregation systems, remains a significant research question

• Protein interaction network:

  • FtsK likely functions within a complex of cell division proteins including FtsI, whose depletion causes dramatic filamentation

  • Identification of B. burgdorferi-specific interaction partners could reveal unique aspects of FtsK function in this spirochete

Advanced research approaches including DNA binding assays with recombinant FtsK domains, chromosome conformation capture techniques, and single-molecule biophysical studies would provide mechanistic insights into the species-specific adaptations of this essential molecular motor.

What experimental challenges exist in studying FtsK activity in the context of B. burgdorferi's unique genomic architecture?

Researchers face several significant challenges when investigating FtsK activity in the context of B. burgdorferi's distinctive genomic organization:

• Complexity of the segmented genome:

  • B. burgdorferi possesses a linear chromosome and numerous circular and linear plasmids (up to 21)

  • This segmented architecture creates experimental difficulties in tracking complete genome segregation

  • Developing fluorescent markers to simultaneously visualize multiple genomic elements presents technical challenges

• In vitro reconstitution limitations:

  • Reproducing the physiological substrate for FtsK (the unique B. burgdorferi chromosome structure) in vitro is technically demanding

  • Linear DNA fragments with telomere-like structures must be engineered to mimic the natural substrate

  • The potential requirement for B. burgdorferi-specific accessory factors may necessitate complex protein purification strategies

• Technological constraints:

  • B. burgdorferi's small cell size (0.2-0.3 μm diameter) pushes the limits of conventional microscopy

  • The spirochete's motility complicates long-term imaging of division processes

  • Limited genetic tools compared to model organisms, though recent advances in CRISPRi technology have improved this situation

• Physiological relevance:

  • Laboratory culture conditions may not accurately reflect the chromosomal dynamics occurring during the natural infection cycle

  • Developing experimental systems that better mimic tick or mammalian host conditions represents an ongoing challenge

How does temperature affect FtsK expression and activity during B. burgdorferi's transmission cycle?

Temperature represents a critical environmental cue that modulates B. burgdorferi gene expression during its transmission cycle, with significant implications for FtsK function:

• Temperature-responsive regulation:

  • B. burgdorferi experiences temperature shifts from ambient (in unfed ticks) to 37°C (in mammalian hosts)

  • These shifts trigger global transcriptional changes through mechanisms including alternative sigma factors and temperature-sensitive DNA topology

  • While specific data on FtsK temperature-dependent expression is limited, the gene likely responds to these regulatory networks

• Growth rate coupling:

  • B. burgdorferi replication rates increase significantly at mammalian body temperature

  • This accelerated growth necessitates upregulation of the cell division machinery, including FtsK

  • At the lower temperatures of unfed ticks, reduced replication rates may correspond with lower FtsK expression

• Protein activity considerations:

  • Beyond expression levels, FtsK ATPase activity itself may exhibit temperature-dependence

  • The enzyme kinetics of DNA translocation could be optimized for the temperature range encountered during active replication phases

  • Structural adaptations in B. burgdorferi FtsK may provide temperature stability across the physiologically relevant range (23-37°C)

• Experimental approaches:

  • Quantitative RT-PCR at different temperatures can establish temperature-dependent expression patterns

  • Biochemical assays with purified recombinant FtsK can determine the temperature-activity profile

  • In vivo localization studies across temperature transitions can reveal changes in protein dynamics

Understanding temperature-dependent regulation of FtsK is particularly important given that temperature serves as a key signal for the pathogen's transition between vector and host environments, potentially coordinating chromosome segregation with other transmission-associated processes.

What role does FtsK play in antibiotic resistance mechanisms in B. burgdorferi?

The potential role of FtsK in antibiotic resistance mechanisms in B. burgdorferi represents an emerging area of investigation with several important considerations:

• Target for DNA replication/segregation inhibitors:

  • As an essential component of chromosome segregation, FtsK represents a potential antibiotic target

  • Compounds that inhibit FtsK ATPase activity or DNA binding could disrupt cell division

  • The structural uniqueness of B. burgdorferi FtsK might allow for spirochete-specific inhibitors

• Stress response coordination:

  • Antibiotic exposure triggers stress responses that often include cell division arrests

  • FtsK may participate in stress-induced division regulation, potentially contributing to tolerance mechanisms

  • The connection between FtsK and the SOS response in B. burgdorferi remains to be characterized

• Persister cell formation:

  • B. burgdorferi can form antibiotic-tolerant persister cells with altered division cycles

  • Changes in FtsK expression or activity may contribute to the persister phenotype

  • Understanding how chromosome segregation processes adapt during persistence could provide insights into recalcitrant infections

• Resistance determinant segregation:

  • If resistance determinants are carried on plasmids, FtsK-mediated effects on plasmid partitioning could influence the stability of resistance

  • The potential interaction between FtsK and plasmid partitioning systems warrants investigation

While B. burgdorferi does not typically acquire antibiotic resistance through horizontal gene transfer, understanding how essential processes like chromosome segregation respond to antibiotic stress may reveal novel approaches to combat persistent infections.

What comparative insights can be gained by studying FtsK across different Borrelia species?

Comparative analysis of FtsK across different Borrelia species provides valuable evolutionary and functional insights:

• Evolutionary conservation patterns:

  • Sequence alignment of FtsK proteins across the Borrelia genus reveals highly conserved motor domains and more variable N-terminal regions

  • The degree of conservation in DNA recognition domains may indicate adaptations to species-specific genome architectures

  • Phylogenetic analysis can identify selective pressures on different FtsK domains across the evolutionary history of these spirochetes

• Pathogenicity correlations:

  • Comparing FtsK between pathogenic species (B. burgdorferi, B. afzelii, B. garinii) and non-pathogenic relatives

  • Identifying any FtsK variations that correlate with host range or tissue tropism differences

  • Evaluating whether FtsK functional differences contribute to the distinct clinical manifestations of different Borrelia species

• Relapsing fever Borrelia comparisons:

  • Contrasting FtsK from Lyme disease Borrelia with relapsing fever Borrelia (e.g., B. hermsii)

  • Examining how FtsK has adapted to the different genomic architectures and antigenic variation systems characteristic of these two Borrelia groups

  • Investigating potential connections between FtsK function and the distinctive infection dynamics of relapsing fever Borrelia

• Methodological approaches:

  • Heterologous complementation studies to test functional conservation

  • Recombinant protein studies comparing biochemical properties

  • Structural biology approaches to identify species-specific adaptations

Comparative genomic approaches combined with functional studies can identify both conserved mechanisms essential to all Borrelia species and specialized adaptations that may contribute to the unique biology of B. burgdorferi.

What are the optimal conditions for measuring FtsK ATPase activity in vitro?

The following optimized protocol enables reliable measurement of B. burgdorferi FtsK ATPase activity:

Reagents and Equipment:

• Purified recombinant B. burgdorferi FtsK (motor domain or full-length protein)

• Reaction buffer: 50 mM Tris-HCl (pH 7.5), 10 mM MgCl₂, 50 mM KCl, 1 mM DTT

• DNA substrates (linear dsDNA, preferably with B. burgdorferi-derived sequences)

• ATP (various concentrations for kinetic analysis)

• Malachite green phosphate detection reagents or EnzChek Phosphate Assay kit

• Temperature-controlled spectrophotometer

Protocol:

• Prepare reaction mixtures containing 50-200 nM purified FtsK protein in reaction buffer

• Add DNA substrate (optimal concentration typically 5-20 nM for 48-50 bp dsDNA)

• Initiate reaction by adding ATP (1-5 mM final concentration)

• Incubate at 23°C and 37°C (both physiologically relevant temperatures)

• At defined time points (0-30 minutes), remove aliquots and measure inorganic phosphate release

Critical Parameters:

• DNA dependency: Include controls without DNA to determine basal ATPase activity

• Salt sensitivity: Optimize KCl concentration (typically 50-150 mM range)

• Temperature effects: Compare activity at tick (23°C) and mammalian (37°C) temperatures

• pH dependence: Activity typically peaks at pH 7.2-7.8

• Divalent cation requirements: Mg²⁺ can be substituted with Mn²⁺ to assess cation specificity

Data Analysis:

• Calculate initial reaction velocities at different ATP concentrations

• Determine Km and Vmax using Michaelis-Menten kinetic analysis

• Compare activity with different DNA substrates to assess sequence specificity

This protocol provides a robust assay for characterizing the biochemical properties of recombinant B. burgdorferi FtsK and serves as a foundation for more complex translocation studies.

How can CRISPR interference be optimized for studying FtsK function in B. burgdorferi?

Optimizing CRISPR interference for FtsK studies in B. burgdorferi requires careful consideration of several parameters:

sgRNA Design Considerations:

• Target selection within ftsK:

  • N-terminal region targeting affects membrane localization

  • C-terminal motor domain targeting disrupts ATPase activity

  • Multiple sgRNAs can be designed to achieve differential effects

• Sequence optimization:

  • Avoid regions with secondary structures that may impair sgRNA function

  • Use predictive algorithms to score potential sgRNAs for effectiveness

  • Select target sites with minimal off-target potential

Expression System Optimization:

• Vector selection based on experimental goals:

  • High-stringency systems (PpQE30 promoter with multiple mutations) for studying essential functions with minimal leakiness

  • Lower-stringency systems for studying phenotypes under partial depletion conditions

• Induction parameters:

  • Titrate IPTG concentrations (typically 0.01-1.0 mM) to achieve desired repression levels

  • Determine optimal timing for phenotypic analysis (24-48 hours post-induction for division phenotypes)

Validation and Controls:

• Quantitative measurements:

  • RT-qPCR to confirm ftsK transcript reduction (aim for >90% reduction)

  • Western blotting if antibodies are available to confirm protein depletion

  • Include non-targeting sgRNA controls to account for dCas9 effects

• Phenotypic characterization:

  • Phase contrast microscopy to observe cell filamentation

  • Fluorescence microscopy with DNA stains to assess chromosome segregation

  • Growth curves to quantify division defects

Experimental Design Table:

By carefully optimizing these parameters, researchers can achieve the 95% or greater repression efficiency demonstrated with other B. burgdorferi genes using CRISPRi technology .

What strategies can overcome the challenges of expressing full-length FtsK for structural studies?

Structural characterization of full-length B. burgdorferi FtsK presents significant challenges due to its membrane-associated N-terminal domain and large size. The following strategies can help overcome these obstacles:

Construct Design Approaches:

• Domain-focused strategies:

  • Express the soluble C-terminal motor domain (typically the final 500 amino acids)

  • Create truncations that retain minimal functional units

  • Design fusion constructs connecting functional domains with flexible linkers

• Membrane protein techniques:

  • Incorporate solubilizing mutations in the transmembrane regions

  • Use fusion partners specifically designed for membrane proteins (Mistic, SUMO)

  • Consider nanodiscs or amphipols for maintaining native-like membrane environments

Expression Optimization:

• Host system selection:

  • C41(DE3) or C43(DE3) E. coli strains engineered for membrane protein expression

  • Insect cell systems for complex proteins resistant to bacterial expression

  • Cell-free systems with added lipids or detergents for direct membrane incorporation

• Expression conditions:

  • Low temperature induction (16°C) for extended periods (16-24 hours)

  • Co-expression with chaperones (GroEL/ES, DnaK/J) to improve folding

  • Reduced inducer concentrations to slow protein production rate

Purification Strategies:

• Detergent screening:

  • Mild detergents (DDM, LMNG) for initial extraction

  • Systematic detergent screening arrays to identify optimal conditions

  • Detergent exchange during purification to improve stability

• Advanced techniques:

  • Styrene maleic acid lipid particles (SMALPs) to extract protein with native lipid environment

  • Amphipathic polymers as alternatives to conventional detergents

  • Lipid nanodiscs for reconstitution of purified protein

Structural Analysis Approaches:

These complementary approaches can collectively overcome the challenges inherent in structural studies of this complex motor protein, providing insights into both conserved features and B. burgdorferi-specific adaptations.

What are the most promising approaches for developing FtsK-targeted antimicrobials against B. burgdorferi?

Developing FtsK-targeted antimicrobials against B. burgdorferi represents a promising avenue with several strategic approaches:

• Structure-based inhibitor design:

  • Targeting the ATPase active site with competitive or allosteric inhibitors

  • Focusing on the unique features of B. burgdorferi FtsK structure

  • Using fragment-based screening to identify initial chemical matter

  • Applying molecular dynamics simulations to identify transient binding pockets

• Functional interference strategies:

  • Disrupting FtsK-DNA interactions through compounds targeting the DNA-binding domain

  • Interfering with protein-protein interactions essential for divisome assembly

  • Developing peptide inhibitors based on natural interaction interfaces

  • Creating DNA mimetics that compete for FtsK binding

• Screening methodologies:

  • High-throughput ATPase activity assays with recombinant protein

  • Whole-cell phenotypic screens looking for filamentation

  • Fluorescence-based DNA translocation assays

  • Virtual screening against structural models

• Delivery considerations:

  • Designing compounds that can penetrate B. burgdorferi's unique outer membrane

  • Exploring prodrug approaches for improved bioavailability

  • Targeting compounds to tissues where B. burgdorferi typically resides

The essential nature of FtsK and its conservation across Borrelia species suggests that successful inhibitors could have broad applicability against multiple Borrelia pathogens. The challenge remains to achieve sufficient selectivity over human proteins to minimize toxicity.

How might advances in cryo-electron tomography further elucidate FtsK function in B. burgdorferi?

Cryo-electron tomography (cryo-ET) offers unprecedented opportunities to study FtsK function in its native cellular context:

• Visualizing the divisome architecture:

  • Mapping the 3D arrangement of division proteins including FtsK

  • Determining the spatial relationship between FtsK and the septal peptidoglycan synthesis machinery

  • Revealing how the division apparatus accommodates the periplasmic flagella

• Chromosome dynamics during segregation:

  • Observing FtsK-DNA interactions in situ

  • Tracking chromosome organization at different stages of segregation

  • Correlating FtsK localization with DNA movement

• Technical advances enabling new insights:

  • Focused ion beam (FIB) milling to access cellular regions previously obscured

  • Correlative light and electron microscopy (CLEM) to precisely locate fluorescently tagged FtsK

  • In situ structural determination approaching subnanometer resolution

  • Time-resolved cryo-ET to capture dynamic processes

• Comparative structural biology:

  • Contrasting divisome architecture across different Borrelia species

  • Identifying structural adaptations specific to the spirochetal cell division process

  • Comparing wild-type and FtsK-depleted cells to determine structural consequences

Cryo-ET has already provided valuable insights into B. burgdorferi flagellar structure and cell division processes . Further applications of this technology, especially when combined with genetic approaches like CRISPRi, promise to reveal the molecular basis of chromosome segregation in this important pathogen.

What potential exists for using FtsK as a target for novel diagnostic approaches for Lyme disease?

FtsK presents several intriguing possibilities as a target for improved Lyme disease diagnostics:

• Serological detection strategies:

  • Identifying B. burgdorferi-specific epitopes in FtsK that elicit antibody responses

  • Developing multiplex assays that include FtsK alongside established antigens

  • Exploring whether FtsK antibodies appear during specific phases of infection

• Molecular detection approaches:

  • Designing species-specific PCR primers targeting unique regions of ftsK

  • Developing LAMP (Loop-mediated isothermal amplification) assays for point-of-care testing

  • Creating multiplex PCR panels that include ftsK among other diagnostic targets

• Functional biomarker applications:

  • Investigating whether FtsK fragments are released during infection

  • Determining if FtsK expression changes in response to antibiotic treatment

  • Exploring potential correlations between FtsK-related biomarkers and treatment outcomes

• Technical considerations:

  • Conservation analysis to identify B. burgdorferi-specific regions

  • Sensitivity/specificity testing against related Borrelia species

  • Validation against diverse clinical isolates

While conventional Lyme diagnostics focus on surface antigens and highly expressed proteins, the essential nature of FtsK and its potential expression during various stages of infection may offer complementary diagnostic value, particularly for difficult-to-detect cases or treatment monitoring.