Recombinant Ochrobactrum anthropi Elongation factor Tu (tuf1)

What is Ochrobactrum anthropi Elongation factor Tu (tuf1)?

Elongation factor Tu (tuf1) from Ochrobactrum anthropi is a GTP-binding protein that plays a central role in bacterial protein synthesis. It facilitates the binding of aminoacylated tRNA molecules to the A site of the ribosome during translation. The full-length protein consists of 391 amino acids and has a Uniprot accession number of A6X0A2. The recombinant form is typically produced in E. coli expression systems with high purity (>85% by SDS-PAGE) for research applications .

How is the tuf1 gene conserved across bacterial species?

The tuf gene is highly conserved across bacterial species, making it valuable for phylogenetic studies and diagnostic applications. Elongation factors originated from a common ancestor via gene duplications and fusions. Bacterial species may contain one to three tuf genes per genome depending on the species. Most low-G+C-content gram-positive bacteria carry only one tuf gene, while some species like certain enterococci contain two different tuf genes (tufA and tufB) . The high conservation of tuf genes makes them excellent targets for the development of universal primers for bacterial detection and identification .

What are the optimal storage and reconstitution conditions for recombinant O. anthropi EF-Tu?

Recombinant O. anthropi EF-Tu should be stored at -20°C for regular storage, or at -80°C for extended storage. Repeated freezing and thawing is not recommended. Before opening, the vial should be briefly centrifuged to bring contents to the bottom. The protein should be reconstituted in deionized sterile water to a concentration of 0.1-1.0 mg/mL. Addition of 5-50% glycerol (final concentration) is recommended before aliquoting for long-term storage at -20°C/-80°C, with 50% being the standard concentration. The shelf life in liquid form is approximately 6 months at -20°C/-80°C, while the lyophilized form maintains stability for about 12 months .

How does the phylogenetic analysis of tuf genes inform our understanding of bacterial evolution?

Phylogenetic analysis of tuf genes provides significant insights into bacterial evolution, particularly regarding horizontal gene transfer events. Studies of enterococcal species revealed that 11 species possess two tuf genes (tufA and tufB), while six species have only one (tufA). The enterococcal tufA gene branches phylogenetically with Bacillus, Listeria, and Staphylococcus genera, whereas the tufB gene clusters with Streptococcus and Lactococcus genera. This pattern suggests horizontal gene transfer from a streptococcal or streptococcus-related species to the common ancestor of the 11 enterococcal species that now carry two tuf genes .

Analysis of amino acid sequences has identified four residues that are conserved and unique to enterococcal tufB genes and the tuf genes of streptococci and Lactococcus lactis, further supporting the horizontal gene transfer hypothesis. Distance matrix trees of bacterial EF-Tu based on amino acid sequence homology can be constructed using the neighbor-joining method, with archaeal and eukaryotic EF-1α genes serving as outgroups .

What are the sequence identity patterns between EF-Tu proteins across different bacterial genera?

Sequence analysis reveals distinct patterns of conservation between different bacterial genera. The sequence identities between different enterococcal tufA genes show high conservation within the group, as do the identities between enterococcal tufB genes. DNA and amino acid sequence comparisons between different bacteria provide valuable information about evolutionary relationships .

For example, analysis of nucleotide and amino acid sequence identities of EF-Tu between different enterococci and other low G+C gram-positive bacteria shows that while the upper right triangle represents the deduced amino acid sequence identities, the lower left triangle represents the DNA sequence identities of the corresponding tuf genes. This type of analysis helps in understanding the evolutionary relationships and potential horizontal gene transfer events in bacterial evolution .

How can O. anthropi be used as a recombinant expression system for vaccine development?

Ochrobactrum anthropi has been successfully used as a recombinant expression system for vaccine development, particularly for Brucella antigens. O. anthropi is closely related to Brucella species, making it a suitable vector for expressing Brucella antigens. For example, O. anthropi strain 49237 has been engineered to express Brucella abortus Cu,Zn superoxide dismutase (SOD) using the broad-host-range plasmid pBBR1MCS .

The recombinant O. anthropi strain 49237SOD, when combined with CpG oligonucleotides to bias the immune response toward a Th1 type, provided significant protection against virulent Brucella infection in mice. The protection conferred by strain 49237SOD was significantly better than that induced by the parental strain, demonstrating the potential of recombinant O. anthropi as a vaccine vector .

This approach offers advantages over traditional vaccine strategies because it allows for the delivery of specific antigens in a context that stimulates appropriate immune responses. The close relationship between O. anthropi and Brucella species may provide additional immunological benefits for vaccine development against brucellosis .

What expression systems are optimal for producing recombinant O. anthropi EF-Tu?

E. coli is the preferred expression system for producing recombinant O. anthropi EF-Tu. The procedure typically involves:

• Cloning the tuf1 gene into a suitable expression vector

• Transformation into an E. coli expression strain

• Induction of protein expression under optimized conditions

• Cell lysis and protein purification through affinity chromatography

• Quality control through SDS-PAGE (ensuring >85% purity)

The choice of tag for purification can be adapted to the specific research needs. The recombinant protein may include a tag for purification, though the specific tag type is determined during the manufacturing process . For functional studies, it's crucial to ensure that the tag does not interfere with the protein's GTP-binding activity or interaction with other components of the translational machinery.

How can researchers verify the functional activity of recombinant EF-Tu?

Functional activity of recombinant EF-Tu can be verified through several complementary approaches:

• GTP Binding Assay: Measuring the protein's ability to bind GTP, which is essential for its function in translation.

• In vitro Translation Assays: Assessing the capacity of the recombinant EF-Tu to support protein synthesis in a cell-free translation system.

• Ribosome Binding Studies: Evaluating the interaction between EF-Tu and ribosomes using techniques such as surface plasmon resonance.

• Aminoacyl-tRNA Binding: Determining the ability of EF-Tu to form a ternary complex with GTP and aminoacyl-tRNA.

• GTPase Activity Measurement: Quantifying the intrinsic and ribosome-stimulated GTPase activity of the protein.

These assays provide comprehensive validation of the functional integrity of the recombinant EF-Tu protein, ensuring its suitability for downstream applications in research .

What techniques are used for analyzing tuf gene diversity in bacterial populations?

Several molecular techniques are employed to analyze tuf gene diversity in bacterial populations:

• PCR Amplification with Degenerate Primers: Designing degenerate PCR primers from consensus sequences to amplify tuf genes from diverse bacterial species.

• DNA Sequencing: Direct sequencing of PCR products or cloned inserts to determine tuf gene sequences.

• Southern Hybridization: Using labeled tuf gene fragments as probes to detect and analyze tuf genes in genomic DNA digests.

• Phylogenetic Analysis: Constructing phylogenetic trees based on tuf gene sequences to understand evolutionary relationships.

• Sequence Identity Matrix Analysis: Comparing nucleotide and amino acid sequences to determine sequence conservation and divergence patterns.

These approaches have been successfully used to identify and characterize tuf genes in various bacterial species, including the discovery of multiple tuf genes in enterococcal species .

How can tuf genes be utilized for bacterial diagnostics and identification?

The highly conserved nature of tuf genes makes them excellent targets for developing diagnostic tools for bacterial identification:

• Universal Primers: Due to their conservation across bacterial species, tuf genes can be targeted with universal primers for broad-range bacterial detection.

• Species-Specific Identification: Variations in tuf gene sequences between species enable the design of species-specific probes and primers.

• Oligonucleotide Probes: Oligonucleotides of at least 12 nucleotides derived from tuf sequences can be used as probes for hybridization-based detection methods.

• Rapid Screening Systems: Universal primers targeting tuf genes allow for rapid screening of clinical specimens to determine bacterial presence.

• Taxonomic Analysis: Sequence analysis of tuf genes can help in taxonomic classification of bacteria, especially for closely related species.

The development of tuf sequence databases comprising both proprietary and public sequences provides a valuable resource for designing primers and probes for the detection and identification of various microorganisms .

What role does EF-Tu play as a target for antimicrobial development?

Elongation factor Tu represents a promising target for antimicrobial development due to its essential role in bacterial protein synthesis:

• Existing Antimicrobial Targets: EF-Tu is known to be the target for antibiotics belonging to the elfamycin group and other structural classes.

• Conserved Function: The essential and conserved function of EF-Tu across bacterial species makes it an attractive target for broad-spectrum antimicrobials.

• Structural Studies: Detailed structural information about EF-Tu facilitates structure-based drug design approaches.

• Resistance Mechanisms: Understanding how bacteria develop resistance to EF-Tu-targeting antibiotics can inform the development of new antimicrobial strategies.

• Selective Toxicity: The differences between bacterial EF-Tu and eukaryotic EF-1α provide opportunities for developing antibiotics with selective toxicity against bacteria.

Research on antimicrobials targeting EF-Tu contributes to addressing the growing challenge of antimicrobial resistance in clinical settings .

How can recombinant O. anthropi be utilized as a vaccine vector platform?

Recombinant O. anthropi shows promise as a vaccine vector platform, particularly for protection against brucellosis:

• Expression of Heterologous Antigens: O. anthropi can be engineered to express protective antigens from pathogens like Brucella abortus.

• Immune Response Modulation: The immune response elicited by recombinant O. anthropi can be modulated, for example, by the addition of CpG oligonucleotides to bias toward a Th1-type response.

• Safety Profile: O. anthropi is closely related to Brucella species but has a better safety profile, making it suitable as a vaccine vector.

• Protection Studies: Animal studies have demonstrated that recombinant O. anthropi expressing B. abortus Cu,Zn SOD can provide protection against virulent Brucella infection when combined with appropriate immune modulators.

• Versatility: The approach can potentially be adapted for developing vaccines against other pathogens by expressing different protective antigens.

This research direction offers promising alternatives to traditional vaccine development strategies, especially for diseases where safe and effective vaccines are currently lacking .