Recombinant Desulfovibrio vulgaris Elongation factor Ts (tsf)

What is Elongation Factor Ts (EF-Ts) and what is its primary function in Desulfovibrio vulgaris?

Elongation Factor Ts (EF-Ts) is a guanosine nucleotide exchange factor that plays a critical role in protein synthesis by facilitating the regeneration of active EF-Tu- GTP from inactive EF-Tu- GDP. In Desulfovibrio vulgaris, as in other bacteria, EF-Ts catalyzes the exchange of GDP for GTP on EF-Tu, enabling the formation of the ternary complex (EF-Tu- GTP- aa-tRNA) necessary for delivering aminoacyl-tRNAs to the ribosome during translation elongation. Research has revealed that EF-Ts serves an unexpected dual function – not only does it catalyze nucleotide exchange on EF-Tu, but it also directly facilitates both the formation and disassociation of the ternary complex . This role in regulating the abundance and stability of the ternary complex contributes to rapid and accurate protein synthesis in the cell .

How does the genetic structure of the tsf gene in D. vulgaris compare to other bacterial species?

The tsf gene in Desulfovibrio vulgaris encodes Elongation Factor Ts and is typically located in an operon structure similar to other bacterial species. While the search results do not specifically detail the genetic structure of tsf in D. vulgaris, genomic analyses typically show that in bacteria, the tsf gene is often co-transcribed with other translation-related genes. The gene organization and regulatory elements may differ from other well-studied bacteria like E. coli, particularly given D. vulgaris' unique adaptations as a sulfate-reducing bacterium. Researchers interested in the tsf gene should perform comparative genomic analyses against reference genomes to identify potential regulatory elements and operon structures specific to D. vulgaris.

What expression systems are most effective for producing recombinant D. vulgaris EF-Ts?

For effective expression of recombinant D. vulgaris EF-Ts, researchers have several options depending on the experimental requirements. While the search results don't specifically mention expression systems for D. vulgaris EF-Ts, we can draw from methodologies used for other D. vulgaris proteins and general recombinant protein expression principles:

• Homologous expression system: Using D. vulgaris itself as an expression host offers advantages for proper folding and post-translational modifications. Recent advances in genetic manipulation of D. vulgaris Hildenborough have made this approach increasingly feasible . The markerless deletion system developed for D. vulgaris provides a platform for introducing expression cassettes for recombinant proteins .

• Heterologous expression in E. coli: For higher yields, E. coli expression systems (particularly BL21(DE3) and its derivatives) remain the most common approach. When expressing D. vulgaris proteins in E. coli, researchers should consider codon optimization to account for the different codon usage between these species.

• Expression vector considerations: Vectors containing the aph(3′)-II promoter (kanamycin resistance gene promoter from Tn5) have shown successful constitutive expression in D. vulgaris , making this a good candidate promoter for tsf expression.

What are the most efficient methods for genetic manipulation of D. vulgaris to express recombinant EF-Ts?

The most efficient methods for genetic manipulation of D. vulgaris to express recombinant EF-Ts involve leveraging recent advances in D. vulgaris genetic tools:

• Markerless deletion system: A significant advancement is the markerless deletion system developed for D. vulgaris Hildenborough, which uses the uracil phosphoribosyltransferase (upp) gene as a counterselectable marker . This system allows for multiple sequential genetic modifications without accumulating antibiotic resistance genes, making it ideal for complex genetic engineering required for optimized protein expression .

• Two-step integration and excision strategy: This approach involves:

  • First, a suicide plasmid containing the gene of interest is integrated into the chromosome by single recombination

  • Subsequently, a second recombination event excises the plasmid backbone, leaving the desired genetic modification

• Transformation efficiency considerations: When introducing expression vectors, using a D. vulgaris strain with enhanced transformation efficiency is beneficial. The JW7035 strain (ΔhsdR) exhibits 100-1,000 times greater transformation efficiency than wild-type when introducing stable plasmids via electroporation , making it a suitable host for recombinant protein expression.

How can I optimize codon usage of the tsf gene for efficient expression in heterologous systems?

Optimizing codon usage of the D. vulgaris tsf gene for heterologous expression requires a methodical approach:

• Codon usage analysis: First, analyze the codon usage bias of both D. vulgaris (source organism) and your expression host. D. vulgaris has a different GC content and codon preference compared to common expression hosts like E. coli.

• Codon adaptation strategy:

  • Replace rare codons in the expression host with more abundant ones without changing the amino acid sequence

  • Focus particularly on clusters of rare codons, which can cause ribosomal stalling

  • Consider maintaining the native codon usage at critical folding regions to ensure proper co-translational folding

• Gene synthesis: Rather than attempting site-directed mutagenesis to change multiple codons, it's often more efficient to synthesize the entire codon-optimized gene.

• Experimental validation: Test the expression of both native and codon-optimized variants to determine if optimization improves yield and solubility.

What factors affect the stability of recombinant D. vulgaris EF-Ts during expression and purification?

Several factors can affect the stability of recombinant D. vulgaris EF-Ts during expression and purification:

• Expression temperature: Lower temperatures (16-25°C) typically slow down protein synthesis, potentially allowing for better folding and increased solubility.

• Buffer composition: Based on knowledge of EF-Ts structure and function:

  • pH considerations: Optimal pH is typically in the range of 7.0-8.0 for most EF-Ts proteins

  • Salt concentration: Moderate ionic strength (100-300 mM NaCl) often helps maintain stability

  • Reducing agents: Including DTT or β-mercaptoethanol can prevent oxidation of cysteine residues

  • Nucleotide consideration: Since EF-Ts interacts with nucleotides, presence of GDP/GTP might affect stability

• Protease inhibitors: Including a cocktail of protease inhibitors during cell lysis and early purification steps can prevent degradation.

• Purification strategy: Affinity tags (His-tag, GST) should be positioned to minimize interference with protein folding and function. Consider testing both N- and C-terminal tag placements.

• Storage conditions: Add glycerol (10-20%) to storage buffers and store at -80°C in small aliquots to prevent freeze-thaw cycles.

How can I measure the nucleotide exchange activity of recombinant D. vulgaris EF-Ts?

To measure the nucleotide exchange activity of recombinant D. vulgaris EF-Ts, researchers can employ several established assays:

• Fluorescence-based assays:

  • MANT-GDP displacement assay: Using the fluorescent GDP analog MANT-GDP (N-methylanthraniloyl-GDP) bound to EF-Tu, monitor the decrease in fluorescence as unlabeled GDP displaces MANT-GDP in the presence of EF-Ts

  • Tryptophan fluorescence: Changes in intrinsic tryptophan fluorescence of EF-Tu upon nucleotide exchange can be monitored in real-time

• Radioactive assays:

  • Filter binding assay: Pre-load EF-Tu with radioactive [³H]GDP or [³⁵S]GTPγS, then measure the EF-Ts-catalyzed release of radioactivity using filter binding

  • Rapid kinetics: Use rapid quench-flow techniques to measure pre-steady-state kinetics of nucleotide exchange

• Steady-state kinetics approach:

  • Determine apparent affinity constants by titrating EF-Tu with varying concentrations of EF-Ts

  • Monitor the formation of EF-Tu- GTP complex as a function of EF-Ts concentration

Based on previous studies with E. coli EF-Ts, fluorescence-based assays using Cy3-labeled tRNA can track ternary complex formation, with EF-Ts causing a measurable increase in fluorescence intensity (~30% above baseline) .

What are the kinetic parameters for D. vulgaris EF-Ts interaction with EF-Tu, and how do they compare to other bacterial species?

While the search results don't provide specific kinetic parameters for D. vulgaris EF-Ts, we can outline the key parameters that researchers should determine and compare to well-characterized systems like E. coli:

• Key kinetic parameters to measure:

  • Rate of GDP dissociation from EF-Tu in the presence of EF-Ts (k₁)

  • Rate of GTP binding to EF-Tu facilitated by EF-Ts (k₂)

  • Binding affinity between EF-Tu and EF-Ts (KD)

  • Rate of ternary complex formation with EF-Tu- GTP and aa-tRNA (k₃)

• Comparative analysis:
  In E. coli, EF-Ts accelerates both the formation and decay rates of ternary complexes through a nucleotide-dependent, rate-determining conformational change in EF-Tu . Research suggests that EF-Ts attenuates the affinity of EF-Tu for GTP and destabilizes ternary complex in the presence of non-hydrolyzable GTP analogs . These findings highlight EF-Ts' role in regulating the abundance and stability of ternary complex.

Researchers should specifically investigate whether D. vulgaris EF-Ts exhibits similar dual functionality in both nucleotide exchange and ternary complex regulation as observed in E. coli.

How does the interaction between D. vulgaris EF-Ts and EF-Tu differ in the presence of various nucleotides and nucleotide analogs?

The interaction between D. vulgaris EF-Ts and EF-Tu likely varies depending on the nucleotide or nucleotide analog present, similar to what has been observed in other bacterial systems. While specific data for D. vulgaris is not provided in the search results, researchers should investigate:

• Nucleotide dependency:

  • Compare EF-Ts activity with GDP vs. GTP bound to EF-Tu

  • Measure binding affinities and exchange rates with different nucleotides

• Non-hydrolyzable GTP analogs:

  • Research in E. coli has shown that EF-Ts destabilizes ternary complex in the presence of non-hydrolyzable GTP analogs

  • Typical analogs to test include GMPPNP, GMPPCP, and GTPγS

• Experimental approach:

  • Employ surface plasmon resonance (SPR) to measure binding kinetics under different nucleotide conditions

  • Use isothermal titration calorimetry (ITC) to determine thermodynamic parameters of binding

  • Test fluorescence-based assays with labeled nucleotides to track exchange in real-time

A systematic comparison across different nucleotides would provide insights into the nucleotide specificity of D. vulgaris EF-Ts and how it might differ from other bacterial species.

How can recombinant D. vulgaris EF-Ts be used to study translation mechanisms in extremophilic sulfate-reducing bacteria?

Recombinant D. vulgaris EF-Ts provides a valuable tool for investigating translation mechanisms in extremophilic sulfate-reducing bacteria:

• Comparative biochemistry approaches:

  • Compare the biochemical properties of D. vulgaris EF-Ts with those from non-extremophiles to identify adaptations for functioning under anaerobic or high-sulfide conditions

  • Analyze temperature and pH optima to understand environmental adaptations

  • Examine structural features that may contribute to stability under extreme conditions

• In vitro translation systems:

  • Develop a D. vulgaris-specific in vitro translation system incorporating purified recombinant components

  • Test the efficiency of translation under various environmental conditions (pH, temperature, sulfide concentration)

  • Compare translation rates and accuracy with and without recombinant EF-Ts to quantify its contribution to translation efficiency

• Structural biology applications:

  • Solve the crystal structure of D. vulgaris EF-Ts alone and in complex with EF-Tu

  • Identify structural elements that differ from mesophilic bacteria and may contribute to its function in extremophilic conditions

• System-level studies:

  • Integrate findings into models of translation regulation in extremophilic bacteria

  • Investigate how translation factors like EF-Ts contribute to adaptation to environmental stress

What role might EF-Ts play in the stress response of D. vulgaris to environmental challenges?

Understanding EF-Ts' role in D. vulgaris stress response provides insights into bacterial adaptation mechanisms:

• Metal stress adaptation:

  • As a sulfate-reducing bacterium, D. vulgaris often encounters heavy metals in its environment

  • Study whether EF-Ts expression changes under metal stress conditions

  • Investigate if post-translational modifications of EF-Ts occur during stress response

• Oxidative stress response:

  • Despite being an anaerobe, D. vulgaris has mechanisms to deal with periodic oxygen exposure

  • Examine EF-Ts stability and function under mild oxidative conditions

  • Determine if EF-Ts is modified or degraded during oxidative stress

• Translational reprogramming during stress:

  • Analyze whether alterations in EF-Ts activity contribute to selective translation of stress-response proteins

  • Compare wild-type and EF-Ts mutant strains for their ability to survive various stresses

• Experimental approaches:

  • Use quantitative proteomics to measure EF-Ts abundance under different stress conditions

  • Perform ribosome profiling to identify changes in translation patterns when EF-Ts activity is altered

  • Create conditional EF-Ts mutants to examine stress survival phenotypes

How can branch-recombinant statistical models be applied to study EF-Ts function in D. vulgaris under perturbation conditions?

Branch-recombinant statistical models offer sophisticated approaches to analyzing EF-Ts function under various perturbations:

• Branch-recombinant Gaussian processes (B-RGPs):

  • B-RGPs provide a framework for analyzing branching and recombination processes in biological time series data

  • These models can identify bifurcation points in statistical processes, which is valuable for detecting when EF-Ts function diverges under different conditions

• Applications to EF-Ts functional studies:

  • Temporal response analysis: Compare time series data of translation efficiency with and without perturbations to EF-Ts

  • Identification of branch times: Determine exactly when EF-Ts function changes in response to environmental perturbations

  • Multi-branch analysis: Study how multiple factors simultaneously affect EF-Ts function

• Experimental design:

  • Collect time-resolved data on EF-Ts activity under control and perturbed conditions

  • Use fluorescence-based assays to continuously monitor nucleotide exchange and ternary complex formation

  • Generate multiple perturbation conditions (temperature, pH, salt concentration) to create branching scenarios

• Data analysis approach:

  • Apply B-RGPs to identify branching points where EF-Ts function diverges from control conditions

  • Group observed behaviors according to the number of branches to separate different response patterns

  • Use these analyses to develop predictive models of how EF-Ts function changes under various conditions

What are the challenges in creating a D. vulgaris strain with modified EF-Ts for studying translation regulation?

Creating D. vulgaris strains with modified EF-Ts presents several technical challenges that researchers should anticipate:

• Essential gene considerations:

  • The tsf gene likely encodes an essential protein, making direct knockouts potentially lethal

  • Strategies must include conditional expression systems or careful point mutations that alter function without eliminating it

• Genetic manipulation challenges:

  • Despite advances in D. vulgaris genetic tools, transformation efficiency remains relatively low compared to model organisms

  • The recently developed markerless deletion system can be leveraged to introduce precise modifications

  • Using the JW7035 strain (ΔhsdR) with 100-1,000× higher transformation efficiency can improve success rates

• Technical implementation:

  • Conditional expression: Develop inducible promoter systems compatible with D. vulgaris

  • Point mutations: Design mutations based on structural knowledge to alter specific aspects of EF-Ts function

  • Tagged variants: Create versions with affinity or fluorescent tags to track localization and interactions

• Verification strategies:

  • Confirm modifications at the genomic level through sequencing

  • Verify protein expression and function through Western blotting and activity assays

  • Assess growth phenotypes under various conditions to determine functional impacts

What structural features distinguish D. vulgaris EF-Ts from other bacterial EF-Ts proteins?

While specific structural information about D. vulgaris EF-Ts is not provided in the search results, researchers should investigate these key aspects:

• Domain organization: Typical bacterial EF-Ts contains an N-terminal domain, a core domain with the EF-Tu binding interface, and a C-terminal domain. Researchers should determine if D. vulgaris EF-Ts maintains this organization or contains unique modifications.

• Conserved interaction motifs: The EF-Tu binding interface typically contains highly conserved residues. Analysis of the D. vulgaris EF-Ts sequence can reveal whether these interaction motifs are preserved or have evolved differently.

• Adaptations to extremophilic lifestyle: As D. vulgaris lives in anaerobic, potentially sulfide-rich environments, its EF-Ts may contain structural adaptations such as:

  • Modified surface charge distribution

  • Altered hydrophobic core packing

  • Reduced number of oxidation-sensitive residues (cysteines)

  • Enhanced stability features for function in its ecological niche

• Experimental approaches:

  • X-ray crystallography or cryo-EM to solve the structure

  • Hydrogen-deuterium exchange mass spectrometry to map flexible regions

  • Comparative modeling based on existing bacterial EF-Ts structures

How does D. vulgaris EF-Ts interact with other components of the translation machinery beyond EF-Tu?

Beyond its canonical interaction with EF-Tu, D. vulgaris EF-Ts likely interacts with other components of the translation machinery:

• Potential interaction partners:

  • Ribosomes: Investigate whether EF-Ts can directly associate with ribosomes under certain conditions

  • tRNAs: Research in E. coli has shown that EF-Ts directly facilitates both formation and disassociation of the ternary complex (EF-Tu- GTP- aa-tRNA) , suggesting direct or indirect interactions with tRNAs

  • Other translation factors: Examine potential interactions with initiation or termination factors

• Regulatory interactions:

  • Metabolic enzymes: In some bacteria, translation factors form complexes with metabolic enzymes to coordinate protein synthesis with metabolic state

  • Stress response proteins: Under stress conditions, EF-Ts may interact with stress-response proteins to modulate translation

• Experimental approaches:

  • Co-immunoprecipitation: Pull-down assays with tagged EF-Ts to identify interaction partners

  • Cross-linking mass spectrometry: To capture transient interactions in vivo

  • Bacterial two-hybrid systems: To screen for potential protein-protein interactions

  • Fluorescence resonance energy transfer (FRET): To study interactions in real-time in living cells

Investigating these interactions would provide insights into the broader role of EF-Ts in coordinating translation with other cellular processes in D. vulgaris.

How can recombinant D. vulgaris EF-Ts be utilized in cell-free protein synthesis systems?

Recombinant D. vulgaris EF-Ts offers unique opportunities for enhancing cell-free protein synthesis (CFPS) systems:

• Development of extremophile-based CFPS:

  • Create CFPS systems that function under anaerobic or high-sulfide conditions

  • Optimize translation efficiency in non-standard environments relevant to biotechnology applications

  • Develop specialized CFPS systems for the production of oxygen-sensitive proteins

• Enhanced translation efficiency:

  • As EF-Ts facilitates nucleotide exchange on EF-Tu and influences ternary complex dynamics , it serves as a critical control point for translation efficiency

  • Adjusting EF-Ts concentration in CFPS can fine-tune protein synthesis rates

  • Engineered EF-Ts variants could be developed with altered kinetic properties for specialized applications

• Implementation strategy:

  • Optimize the ratio of EF-Ts to EF-Tu in the CFPS system

  • Compare performance with EF-Ts from different bacterial sources (mesophiles vs. extremophiles)

  • Combine with other translation factors from D. vulgaris to create a complete sulfate-reducing bacteria-derived translation system

• Potential advantages:

  • CFPS systems incorporating D. vulgaris components may show enhanced stability under reducing conditions

  • Such systems could enable the synthesis of metalloproteins or oxygen-sensitive enzymes that are challenging to produce in conventional systems

What experimental approaches can be used to determine if D. vulgaris EF-Ts contributes to antibiotic resistance mechanisms?

Investigating D. vulgaris EF-Ts' potential role in antibiotic resistance requires systematic experimental approaches:

• Susceptibility testing:

  • Compare antibiotic sensitivity of wild-type D. vulgaris with strains overexpressing or containing modified EF-Ts

  • Test a panel of antibiotics targeting different steps of translation (tetracyclines, aminoglycosides, macrolides)

  • Determine minimum inhibitory concentrations (MICs) and growth inhibition curves

• Molecular mechanisms:

  • Direct binding studies: Assess if antibiotics directly interact with EF-Ts using techniques like isothermal titration calorimetry

  • Competition assays: Determine if antibiotics compete with natural ligands for binding to EF-Ts

  • Structural analysis: Use X-ray crystallography or cryo-EM to visualize potential antibiotic binding sites

• Functional assays:

  • In vitro translation: Compare the effect of antibiotics on translation systems with different levels or variants of EF-Ts

  • Nucleotide exchange assays: Test if antibiotics affect the nucleotide exchange function of EF-Ts

  • Ternary complex formation: Examine how antibiotics influence EF-Ts' role in ternary complex dynamics

• Genetic approaches:

  • Generate point mutations in EF-Ts and screen for antibiotic resistance phenotypes

  • Perform adaptive laboratory evolution under antibiotic selection and sequence tsf gene in evolved strains

  • Use the markerless genetic manipulation system to introduce specific modifications to the tsf gene

Understanding EF-Ts' potential contribution to antibiotic resistance could provide new insights into bacterial adaptation and potentially identify novel targets for antimicrobial development.