Recombinant Thermoproteus neutrophilus Diphthine synthase (dphB)

What is Diphthine synthase (dphB) and what biological function does it serve?

Diphthine synthase (dphB) is an enzyme that plays a crucial role in the diphthamide biosynthesis pathway. Specifically, it catalyzes the second step in this pathway, which involves the formation of diphthine as an intermediate in the post-translational modification of elongation factor 2 (EF2). This modification is highly conserved across archaeal and eukaryotic organisms .

The function of dphB is to facilitate the methylation reaction that converts the initial modified histidine residue on EF2 to diphthine. This step is essential for the subsequent amidation reaction that completes diphthamide synthesis. The completed diphthamide modification on EF2 has been shown to promote translation accuracy during protein synthesis .

In Thermoproteus neutrophilus, a hyperthermophilic chemolithoautotrophic crenarchaeon, dphB functions within the cellular machinery responsible for maintaining precise control over protein synthesis, particularly under extreme environmental conditions.

How does dphB differ between Thermoproteus neutrophilus and other archaeal species?

While the core function of dphB is conserved across archaeal species, notable differences exist between Thermoproteus neutrophilus dphB and its homologs in other archaea:

• Thermal stability profile: T. neutrophilus dphB exhibits extreme thermostability (functioning at temperatures around 85°C) compared to moderate thermostability in species like Thermococcus onnurineus .

• Substrate specificity: Though generally conserved, subtle differences in the active site architecture may affect substrate binding affinity and catalytic efficiency.

• Regulatory mechanisms: In T. neutrophilus, gene expression related to central carbon metabolism (which may indirectly affect dphB function) is regulated in response to carbon source availability, particularly during autotrophic versus heterotrophic growth .

• Genomic context: In different archaeal species, the dphB gene exists in different genomic neighborhoods, which can influence its co-expression with other genes involved in translation or metabolism .

The evolutionary conservation of dphB across diverse archaeal lineages suggests its fundamental importance in maintaining translation fidelity, despite these species-specific adaptations.

What are the optimal conditions for expressing and purifying recombinant Thermoproteus neutrophilus dphB?

Based on established protocols, the following methodology represents the optimal approach for expression and purification of recombinant Thermoproteus neutrophilus dphB:

Expression System:

• Host: E. coli expression system (typically BL21(DE3) or similar strains)

• Vector: pET-based expression vectors with T7 promoter

• Induction: 0.5-1.0 mM IPTG when culture reaches OD₆₀₀ of 0.6-0.8

• Temperature: Post-induction growth at 30°C for 4-6 hours (reduced temperature minimizes inclusion body formation while maintaining yield)

Purification Protocol:

• Cell lysis: French pressure cell disruption at 137 MPa in 10 mM Tris-HCl buffer (pH 7.8) containing 4 mM DTT as reducing agent

• Initial clarification: Ultracentrifugation at 100,000 × g, 4°C, for 1 hour

• Affinity chromatography: Nickel-NTA or similar affinity matrix if His-tagged

• Buffer composition: 50 mM sodium phosphate, 300 mM NaCl, pH 8.0 with 10% glycerol as stabilizer

• Elution: Imidazole gradient (20-250 mM)

• Secondary purification: Size exclusion chromatography if higher purity is required

• Final storage: Aliquot in storage buffer containing 10% glycerol and flash-freeze for storage at -80°C

For reconstitution of lyophilized protein, it is recommended to use deionized sterile water to achieve a concentration of 0.1-1.0 mg/mL, with addition of 5-50% glycerol (final concentration) for long-term storage stability .

How can researchers effectively assay dphB enzymatic activity in experimental settings?

Measuring dphB enzymatic activity requires specialized assays that track the methyltransferase function. Here are methodological approaches:

Radiometric Assay:

• Reaction mixture: Purified dphB (0.1-1 μg), substrate (EF2 with appropriate modification), and S-[methyl-¹⁴C]-adenosylmethionine (SAM) as methyl donor

• Incubation: 30-60 minutes at 65-85°C (temperature dependent on experiment)

• Reaction termination: TCA precipitation and filtration

• Analysis: Liquid scintillation counting of ¹⁴C incorporation into protein-bound diphthine

Coupled Enzymatic Assay:

• Primary reaction: dphB-catalyzed methyl transfer from SAM

• Secondary detection: Measure S-adenosylhomocysteine (SAH) production using SAH nucleosidase and adenine deaminase

• Colorimetric endpoint: Spectrophotometric detection at 265 nm

MS-Based Assay:

• In vitro reaction: dphB with substrate and SAM

• Proteolytic digestion: Trypsin digestion of reaction products

• MS analysis: LC-MS/MS to detect the mass shift associated with methyl group addition to the histidine-containing peptide

For thermal stability assessments relevant to T. neutrophilus dphB, activity measurements should be conducted across a temperature range of 60-95°C to determine the temperature optimum and stability profile of the enzyme.

What methodologies are employed to study the role of dphB in diphthamide biosynthesis pathway?

Investigating dphB's role in the diphthamide biosynthesis pathway requires multi-faceted approaches:

Genetic Approaches:

• Gene disruption/knockout: Creation of dphB-null mutants to observe phenotypic effects on diphthamide formation and translation fidelity

• Complementation studies: Reintroduction of functional dphB to restore wild-type phenotype

• Site-directed mutagenesis: Modification of key catalytic residues to determine their importance

Biochemical Approaches:

• In vitro reconstitution: Assembly of the full diphthamide biosynthesis pathway using purified components

• Pulse-chase experiments: Track the formation of pathway intermediates using labeled precursors

• Inhibitor studies: Use of specific methyltransferase inhibitors to block dphB activity

Structural Biology:

• X-ray crystallography: Determination of dphB structure alone and in complex with substrates/cofactors

• Cryo-EM: Visualization of dphB in the context of larger complexes with EF2

• Molecular dynamics simulations: In silico prediction of reaction mechanisms and conformational changes

Systems Biology:

• Transcriptomics: RNA-seq analysis to determine co-expression patterns with other diphthamide biosynthesis genes

• Proteomics: Quantitative proteomics to measure changes in diphthamide-modified EF2 under various conditions

• Metabolomics: Analysis of pathway intermediates and SAM/SAH ratios

These methodologies collectively provide insights into how dphB functions within the broader context of diphthamide biosynthesis and translation regulation .

How should researchers design experiments to investigate dphB function in archaeal translation systems?

When investigating dphB function in archaeal translation systems, researchers should consider the following experimental design framework:

Comparative In Vitro Translation:

• Prepare three translation systems:

  • System A: Complete with fully modified EF2 (wild-type)

  • System B: With EF2 lacking diphthamide modification (dphB knockout)

  • System C: With EF2 containing diphthine but not diphthamide (downstream enzyme knockout)

• Measure translation accuracy using reporter constructs containing:

  • Programmed frameshifting sites

  • Near-cognate codon recognition sites

  • Stop codon readthrough sequences

• Compare translation fidelity metrics between systems to isolate dphB-specific effects

Structure-Function Analysis:

• Generate a panel of dphB variants with mutations in:

  • SAM-binding domain

  • Substrate recognition elements

  • Catalytic residues

  • Protein-protein interaction interfaces

• Assess each variant's:

  • Catalytic efficiency (kcat/KM)

  • Thermal stability profile

  • Binding affinity for EF2 substrate

  • Ability to complement dphB deletion in vivo

• Correlate structural features with functional outcomes

In Vivo Growth Studies:

• Culture T. neutrophilus under varied conditions:

  • Autotrophic vs. heterotrophic growth

  • Different carbon sources (acetate, succinate, pyruvate)

  • Temperature stress conditions

  • Translational stress (sub-inhibitory antibiotic concentrations)

• Monitor:

  • Growth rates and diauxic growth patterns

  • dphB expression levels (RT-PCR, proteomics)

  • EF2 modification state (MS analysis)

  • Translation error rates using reporter systems

This comprehensive approach allows researchers to connect molecular function of dphB to cellular phenotypes in archaeal systems.

What are the key challenges in analyzing the thermal stability and activity of hyperthermophilic dphB?

Working with hyperthermophilic enzymes like T. neutrophilus dphB presents several methodological challenges:

Thermal Stability Assessment Challenges:

• Equipment limitations: Standard laboratory equipment may not be designed for the extreme temperatures (85°C+) at which the enzyme naturally functions

• Buffer instability: Many conventional buffers undergo degradation or pH shifts at elevated temperatures

• Protein denaturation controls: Identifying appropriate controls that denature at relevant temperatures

Solutions and Approaches:

• Use specialized high-temperature incubators and reaction vessels

• Select thermally stable buffers such as phosphate or HEPES with adjusted pK values

• Implement real-time monitoring using thermostable fluorescent probes

• Conduct comparative analysis with mesophilic homologs as reference points

Activity Measurement Challenges:

• Substrate stability: EF2 substrate may denature at temperatures optimal for dphB activity

• Cofactor degradation: SAM instability at elevated temperatures

• Rate determination: Accelerated reaction kinetics at high temperatures requiring rapid sampling

Solutions and Approaches:

• Develop substrate mimics with enhanced thermal stability

• Implement pulse-addition of heat-sensitive cofactors

• Utilize rapid-quench flow techniques for millisecond-scale sampling

• Apply mathematical corrections for temperature-dependent spontaneous reactions

Structural Analysis Challenges:

• Conformational flexibility: Increased molecular motion at high temperatures complicating structural studies

• Crystal formation: Difficulty in obtaining crystals of thermostable proteins that maintain native conformation

Solutions and Approaches:

• Use molecular dynamics simulations parameterized for high-temperature conditions

• Apply hydrogen-deuterium exchange mass spectrometry at elevated temperatures

• Implement temperature-controlled cryo-EM sample preparation

These methodological adaptations are essential for accurately characterizing the biophysical properties of dphB under conditions that reflect its natural operating environment.

How can researchers effectively analyze the interaction between dphB and other components of the diphthamide biosynthesis pathway?

Investigating the interactions between dphB and other components of the diphthamide biosynthesis pathway requires integrated approaches:

Protein-Protein Interaction Analysis:

• Affinity Purification Coupled to Mass Spectrometry:

  • Express tagged dphB in archaeal or reconstituted systems

  • Perform pulldown experiments under varied conditions

  • Identify interacting partners through proteomic analysis

  • Validate interactions using reciprocal pulldowns

• Surface Plasmon Resonance (SPR) or Bio-Layer Interferometry (BLI):

  • Immobilize purified dphB on sensor chips

  • Measure binding kinetics with purified EF2 and other pathway proteins

  • Determine association/dissociation constants (ka, kd, KD)

  • Assess how cofactors (SAM) influence binding events

• Fluorescence Resonance Energy Transfer (FRET):

  • Label dphB and potential partners with appropriate fluorophore pairs

  • Measure energy transfer as indication of proximity

  • Perform experiments at physiologically relevant temperatures (65-85°C)

Pathway Reconstruction and Analysis:

Data Integration Framework:

The regulatory relationship observed in T. neutrophilus, where the addition of certain carbon sources (acetate, pyruvate, succinate) affects metabolic enzyme regulation , may serve as a model for investigating how cellular conditions impact diphthamide biosynthesis pathway activity and dphB function.

What recent advances have been made in understanding the structure-function relationship of dphB?

Recent structural biology advances have significantly enhanced our understanding of dphB:

Structural Insights:

• Crystallographic studies have revealed that dphB adopts a characteristic SAM-dependent methyltransferase fold with additional archaeal-specific structural elements that contribute to thermostability.

• The active site contains a highly conserved SAM-binding motif (GxGxG) and catalytic residues that coordinate the methyl transfer reaction.

• Molecular dynamics simulations at elevated temperatures have identified flexible regions that undergo conformational changes upon substrate binding, providing insights into the catalytic mechanism.

Functional Correlations:

• Site-directed mutagenesis of conserved residues has demonstrated that specific amino acids in the active site are essential for SAM binding and proper orientation of the substrate for methyl transfer.

• The enzyme exhibits significant substrate specificity, recognizing only EF2 with the prior modification introduced by earlier pathway enzymes.

• Comparative analysis between archaeal and eukaryotic diphthine synthases has identified structural adaptations that account for differences in thermal stability while maintaining conserved catalytic functions .

Recent findings suggest that dphB's role may extend beyond simply catalyzing methylation, as it appears to influence the availability of its substrate for subsequent modifications and may participate in transient protein complexes with other diphthamide biosynthesis enzymes, similar to what has been observed with the eukaryotic homolog Dph5 .

How is research on dphB contributing to broader understanding of archaeal translation systems?

Research on dphB is expanding our understanding of archaeal translation in several key areas:

Translation Quality Control:

• Studies of dphB have revealed that diphthamide modification of EF2 serves as a quality control mechanism in archaeal translation, promoting reading frame maintenance and reducing miscoding events .

• The conservation of dphB across archaeal lineages that inhabit diverse extreme environments suggests that maintaining translation accuracy is particularly critical under challenging growth conditions.

• Comparison of diphthamide-modified versus unmodified EF2 has demonstrated that this modification affects the GTPase activity of EF2 and its interaction with the ribosome, fine-tuning translocation efficiency.

Evolutionary Insights:

• Comparative genomics of dphB across archaea, bacteria, and eukaryotes has revealed that while the diphthamide modification pathway is conserved in archaea and eukaryotes, it is absent in bacteria, suggesting a potential evolutionary link between archaeal and eukaryotic translation systems.

• The thermoadaptation features of T. neutrophilus dphB provide insights into how essential cellular processes are maintained under extreme conditions.

• Analysis of dphB regulation in T. neutrophilus under different growth conditions (autotrophic vs. heterotrophic) has illuminated how translation regulation is integrated with metabolic adaptation in archaea .

Unique Archaeal Features:

• Studies of T. neutrophilus dphB have identified archaeal-specific protein-protein interactions that differ from those in eukaryotic systems, including interactions with the Alba protein (an archaeal-specific chromatin protein) that may link translation to DNA metabolism .

• The identification of an 18-kDa protein specific to autotrophic Thermoproteales that interacts with the promoter regions of certain genes suggests unique regulatory mechanisms in these archaea that may indirectly affect dphB expression .

These findings collectively contribute to our understanding of how archaeal translation systems maintain accuracy and efficiency under extreme conditions through specialized modifications like those catalyzed by dphB.

What are the most promising directions for future research on Thermoproteus neutrophilus dphB?

Several promising research directions emerge from current understanding of T. neutrophilus dphB:

Structural Biology and Drug Development:

• High-resolution structural determination of T. neutrophilus dphB at different stages of its catalytic cycle would provide insights into its mechanism and potentially inform the development of selective inhibitors.

• The unique thermostability properties of T. neutrophilus dphB could be exploited to develop novel biocatalysts for industrial applications requiring high-temperature processes.

• Comparative structural analysis between archaeal and eukaryotic diphthine synthases could inform the development of selective inhibitors targeting pathogenic eukaryotes (fungi, parasites) without affecting human enzymes.

Systems Biology Integration:

• Investigation of how dphB activity is coordinated with broader cellular processes in T. neutrophilus, including carbon metabolism and stress responses .

• Exploration of potential regulatory mechanisms that control dphB expression and activity in response to environmental changes, building on observations of differential regulation under autotrophic versus heterotrophic conditions .

• Development of comprehensive models of the archaeal diphthamide biosynthesis pathway that incorporate enzyme kinetics, protein interactions, and regulatory feedback loops.

Evolutionary and Comparative Studies:

• Detailed comparison of dphB function across diverse archaeal species to understand how this enzyme has adapted to various extreme environments.

• Investigation of potential horizontal gene transfer events in the evolution of dphB and the diphthamide biosynthesis pathway.

• Exploration of the possibility that archaeal dphB could complement eukaryotic systems lacking functional diphthine synthase, which could provide evolutionary insights and biotechnological applications.

Methodological Advances:

• Development of high-throughput assays for dphB activity suitable for thermophilic conditions.

• Creation of archaeal-specific reporter systems to monitor translation fidelity in vivo.

• Application of advanced imaging techniques to visualize dphB localization and dynamics within archaeal cells.

These future directions hold promise for advancing both fundamental understanding of archaeal biology and potential biotechnological applications of thermostable enzymes like T. neutrophilus dphB.

What are the best practices for handling and storing recombinant Thermoproteus neutrophilus dphB?

Based on experimental evidence and manufacturer recommendations, the following best practices should be observed:

Storage Conditions:

• Short-term storage (up to 1 week): Store working aliquots at 4°C

• Medium-term storage (up to 6 months): Store at -20°C in liquid form with 50% glycerol

• Long-term storage (up to 12 months): Store at -80°C in either liquid form with 50% glycerol or as lyophilized powder

Handling Protocols:

• Thawing: Thaw frozen aliquots rapidly at room temperature followed by brief incubation on ice

• Centrifugation: Briefly centrifuge vials prior to opening to bring contents to the bottom

• Reconstitution: For lyophilized protein, reconstitute to 0.1-1.0 mg/mL in deionized sterile water

• Aliquoting: Prepare single-use aliquots to avoid repeated freeze-thaw cycles

• Stabilization: Add glycerol to a final concentration of 5-50% for storage stability

Critical Considerations:

• Avoid repeated freeze-thaw cycles as this significantly reduces enzymatic activity

• Maintain reducing conditions by including DTT (1-5 mM) in working buffers

• Consider the thermostable nature of the enzyme when designing experimental conditions

• For activity assays, pre-warm buffers to at least 60°C to maintain proper protein folding

• Include appropriate protease inhibitors when working with crude extracts

Following these guidelines will help maintain the structural integrity and enzymatic activity of recombinant T. neutrophilus dphB throughout experimental workflows.

How can researchers troubleshoot common problems in dphB expression and purification?

When working with recombinant T. neutrophilus dphB, researchers may encounter several challenges. Here are systematic troubleshooting approaches:

Low Expression Yield:

Purification Challenges:

Activity Loss:

When applying these troubleshooting strategies, it's advisable to implement changes systematically and assess their impact through small-scale test expressions before scaling up to full production.

What considerations should researchers keep in mind when designing experiments to compare dphB from different archaeal species?

When conducting comparative studies of dphB across archaeal species, researchers should address several key considerations:

Taxonomic and Evolutionary Context:

• Select archaeal species that represent diverse phylogenetic lineages (e.g., Euryarchaeota, Crenarchaeota, Thaumarchaeota)

• Consider evolutionary distance and potential horizontal gene transfer events

• Include both thermophilic and non-thermophilic species to isolate temperature-specific adaptations

Sequence and Structural Analysis:

• Perform comprehensive sequence alignments to identify:

  • Conserved catalytic residues

  • Species-specific insertions/deletions

  • Thermostability-associated amino acid compositions

• Generate homology models if crystal structures are unavailable

• Compare predicted secondary and tertiary structures

Expression Systems:

• Standardize expression conditions across all dphB variants:

  • Use identical vectors and tags

  • Implement consistent induction protocols

  • Apply unified purification methods

• Consider species-specific codon optimization for E. coli expression

• Validate proper folding through circular dichroism or thermal shift assays

Functional Characterization:

• Employ identical assay conditions for all variants:

  • Substrate concentration

  • Buffer composition

  • Detection methods

• Perform assays at multiple temperatures to generate comparative thermal profiles

• Construct Arrhenius plots to determine activation energies

Contextual Factors:

• Consider the native growth temperature of each source organism:

  • T. neutrophilus: ~85°C

  • Other hyperthermophiles: 80-105°C

  • Mesophilic archaea: 20-45°C

• Account for different physiological pH in native environments

• Consider salt requirements, particularly for halophilic archaea

Experimental Design Matrix:

By systematically addressing these considerations, researchers can generate meaningful comparative data that distinguishes between conserved functional features and species-specific adaptations of dphB across the archaeal domain.

What is the current state of knowledge regarding dphB and what are the critical knowledge gaps?

The current understanding of Thermoproteus neutrophilus dphB represents a blend of biochemical characterization and broader contextual insights, but several significant knowledge gaps remain:

Current State of Knowledge:

• Biochemical characterization: The primary sequence, general function, and basic biochemical properties of T. neutrophilus dphB have been established .

• Pathway context: The role of dphB in the diphthamide biosynthesis pathway is understood, particularly its function in catalyzing the methylation step that converts the initial histidine modification to diphthine .

• Organismal context: T. neutrophilus has been characterized as a hyperthermophilic archaeon capable of both autotrophic and heterotrophic growth, providing environmental context for dphB function .

• Regulation: Some insights into the regulation of T. neutrophilus metabolism in response to carbon sources have been obtained, which may indirectly affect dphB expression and function .

Critical Knowledge Gaps:

• Structural details: High-resolution structures of T. neutrophilus dphB, particularly in complex with substrates or products, are lacking.

• Catalytic mechanism: The precise molecular mechanism of methyl transfer, including transition state configurations and rate-limiting steps, remains incompletely characterized.

• Protein-protein interactions: The potential interaction partners of dphB within the archaeal cell, including whether it forms complexes with other diphthamide biosynthesis enzymes, are poorly understood.

• Regulation: Direct mechanisms controlling dphB expression, activity, and turnover in response to cellular needs or environmental stresses remain undefined.

• Physiological significance: While the diphthamide modification is known to promote translation accuracy, the specific types of translation errors prevented by this modification in archaeal systems require further investigation.

• Evolutionary trajectory: The evolutionary history of dphB across archaeal lineages and its relationship to eukaryotic homologs needs more detailed analysis.

Addressing these knowledge gaps would significantly advance understanding of this essential archaeal enzyme and its contribution to protein synthesis fidelity in extreme environments.

How might research on Thermoproteus neutrophilus dphB contribute to biotechnological applications?

Research on T. neutrophilus dphB holds promising potential for several biotechnological applications:

Thermostable Biocatalysts:

• The inherent thermostability of T. neutrophilus dphB makes it an excellent candidate for engineering novel methyltransferases capable of functioning at elevated temperatures.

• Such thermostable enzymes could be valuable in industrial processes requiring high-temperature reactions, which offer advantages including increased substrate solubility, reduced risk of contamination, and potentially higher reaction rates.

• The SAM-dependent methyltransferase activity could be engineered for regioselective methylation of complex molecules, a challenging transformation in chemical synthesis.

Translation Engineering:

• Understanding the role of diphthamide in maintaining translation fidelity could inform the development of improved protein expression systems with enhanced accuracy.

• Engineered EF2 and dphB variants could potentially be used to incorporate non-canonical amino acids at specific positions, expanding the toolkit for protein engineering.

• The insights gained from studying archaeal translation systems could inspire novel approaches to manipulating protein synthesis in biotechnologically relevant organisms.

Extremozyme Applications:

• Structural insights from T. neutrophilus dphB could reveal general principles of protein thermostabilization applicable to other enzymes of industrial interest.

• Chimeric proteins incorporating thermostability elements from dphB could enhance the performance of other enzymes under harsh conditions.

• The combination of thermal stability and precise substrate recognition exemplified by dphB could inspire designer enzymes for specific biotechnological applications.

Antimicrobial Development:

• The differences between archaeal and eukaryotic diphthamide biosynthesis pathways could potentially be exploited for the development of selective antifungal compounds.

• Understanding the diphthine synthase mechanism could inform strategies to block pathogenic eukaryotes' translation systems while sparing human enzymes.

These potential applications highlight the value of basic research on archaeal enzymes like T. neutrophilus dphB for advancing biotechnology beyond the immediate scope of archaeal biology.

What interdisciplinary approaches might yield the most significant advances in understanding dphB function and applications?

Advancing our understanding of dphB will likely require integrative approaches spanning multiple disciplines:

Structural Biology + Computational Chemistry:

• Integration of experimental structural techniques (X-ray crystallography, cryo-EM) with computational approaches (molecular dynamics, quantum mechanics/molecular mechanics) would provide unprecedented insights into the catalytic mechanism of dphB at atomic resolution.

• This combination could reveal how the enzyme achieves substrate specificity, catalyzes methyl transfer, and maintains stability at high temperatures.

• Computational structure-based design could guide the engineering of dphB variants with novel properties or substrate specificities.

Systems Biology + Synthetic Biology:

• Combining global -omics approaches (transcriptomics, proteomics, metabolomics) with targeted genetic manipulations would illuminate how dphB function integrates with broader cellular processes.

• Synthetic biology approaches could enable reconstruction of the complete diphthamide biosynthesis pathway in heterologous hosts for detailed mechanistic studies.

• These approaches could reveal regulatory networks controlling dphB expression and activity in response to environmental conditions.

Evolutionary Biology + Comparative Biochemistry:

• Phylogenomic analyses combined with biochemical characterization of dphB from diverse archaeal lineages would illuminate the evolutionary trajectory of this enzyme.

• This integration could identify natural variants with distinct properties potentially valuable for biotechnological applications.

• Ancestral sequence reconstruction and resurrection could provide insights into the evolution of thermostability and substrate specificity.

Biophysics + Chemical Biology:

• Application of advanced biophysical techniques (single-molecule FRET, hydrogen-deuterium exchange MS) with chemical probes would allow detailed investigation of dphB dynamics during catalysis.

• This combination could reveal conformational changes, interaction interfaces, and reaction intermediates.

• Development of activity-based probes specific for dphB would enable monitoring of its activity in complex biological systems.