Recombinant Corynebacterium urealyticum Elongation factor Tu (tuf)

Definition and Biological Role

Recombinant Corynebacterium urealyticum Elongation Factor Tu (EF-Tu), encoded by the tuf gene, is a GTP-binding protein central to protein synthesis. It facilitates the binding of aminoacylated tRNA molecules to the ribosome's A-site during translation elongation . EF-Tu is highly conserved across bacterial species, making it a critical target for both antimicrobial development and diagnostic applications . The recombinant form is produced via genetic engineering to study its structural, functional, and immunological properties.

Gene and Protein Structure

• Gene Location: The tuf gene in C. urealyticum is part of the str operon, co-transcribed with fusA (encoding elongation factor G) .

• Protein Features:

  • Molecular Weight: ~50 kDa (based on homologs like Lactobacillus reuteri EF-Tu) .

  • Functional Domains: GTPase domain, tRNA-binding region, and ribosome-interaction motifs .

  • Conservation: Shares >95% amino acid identity with EF-Tu from other Corynebacterium species .

Sequence Variability

• Variable Regions: While the core structure is conserved, surface-exposed regions exhibit variability, enabling species-specific immune recognition .

• Duplication: Some bacterial species harbor multiple tuf paralogs (e.g., tufA and tufB), but C. urealyticum retains a single copy .

Diagnostic Use

EF-Tu’s conserved regions serve as targets for universal bacterial detection. Key applications include:

• Pathogen Identification: PCR primers targeting tuf enable broad-spectrum bacterial detection in clinical samples .

• Antimicrobial Resistance (AMR) Profiling: EF-Tu mutations linked to elfamycin resistance (e.g., in Mycobacterium) are monitored using recombinant variants .

Probiotic Research

In Corynebacterium spp., EF-Tu contributes to adhesion and stress tolerance:

• Adhesion: Binds host extracellular matrix proteins via surface-exposed domains .

• Oxidative Stress Response: Co-expressed with antioxidant genes (e.g., trx, katE) in probiotic strains .

Genomic Insights

• Gene Context: The C. urealyticum DSM 7109 genome (RefSeq: GCF_000069945) reveals tuf located within a 2.37 Mb chromosome, adjacent to fusA .

• Phylogenetic Analysis: tuf phylogeny aligns C. urealyticum with pathogenic corynebacteria (e.g., C. jeikeium), highlighting evolutionary adaptations for urinary tract colonization .

Antibiotic Interactions

• Target for Elfamycins: EF-Tu’s GTPase activity is inhibited by elfamycin-class antibiotics, disrupting translation .

• Resistance Mechanisms: Mutations in EF-Tu’s GTP-binding pocket reduce drug affinity, as observed in rifampicin-resistant strains .

Table 1: tuf Gene and Protein Attributes

Table 2: Functional Roles of EF-Tu in C. urealyticum

Challenges and Future Directions

• Heterologous Expression: Recombinant EF-Tu production in E. coli faces solubility issues, necessitating optimized codon usage .

• Immunogenicity Studies: EF-Tu’s role as a vaccine candidate requires further exploration of its antigenic epitopes .