Recombinant Brucella melitensis biotype 2 Serine hydroxymethyltransferase (glyA)
Description
Overview of Serine Hydroxymethyltransferase (glyA)
Serine hydroxymethyltransferase (SHMT), encoded by the glyA gene, is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the reversible conversion of serine to glycine and tetrahydrofolate (THF) to 5,10-methylene-THF. This enzyme plays a critical role in one-carbon metabolism, linking amino acid biosynthesis with nucleotide and methylation processes . In Brucella melitensis, SHMT is hypothesized to contribute to intracellular survival by supporting serine/glycine homeostasis and metabolic adaptation in host environments .
Genomic Organization
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B. melitensis possesses two circular chromosomes (3.29 Mbp total) encoding 3,197 open reading frames (ORFs) .
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Although glyA is not explicitly highlighted in provided genomic studies, metabolic models confirm its presence in central pathways (e.g., folate cycle, glycine/serine interconversion) .
Proteomic Expression
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Comparative proteomics of B. melitensis versus B. abortus reveals differential expression of metabolic enzymes, including those in serine/glycine pathways . SHMT’s abundance may vary under host-specific stress .
Cloning and Purification Strategies
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Affinity Tagging: In C. glutamicum, His-tagged glyA was expressed in E. coli M15/pREP4, purified via Ni²⁺-nitrilotriacetic acid chromatography, and showed activity of 1.3 µmol/min/mg with serine .
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Inducible Systems: IPTG-inducible promoters (e.g., tac) enable controlled expression, critical for studying essential genes like glyA .
Implications for Pathogenicity and Vaccine Development
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Metabolic Auxotrophy: B. abortus serine auxotrophs (serB mutants) show 2-log reduced splenic colonization in mice, underscoring serine biosynthesis as a virulence factor .
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Immune Evasion: Rough LPS phenotypes (e.g., GI-2 mutants) alter Toll-like receptor signaling, but SHMT’s role in LPS biosynthesis remains uncharacterized .
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Vaccine Targets: Recombinant outer membrane proteins (e.g., rOmp31) elicit Th1 responses in mice, but SHMT has not yet been explored as an antigen .
Research Gaps and Future Directions
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Direct Functional Studies: No published data exists on recombinant B. melitensis SHMT activity or structure.
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Host-Pathogen Dynamics: Elucidate SHMT’s contribution to intracellular serine scavenging versus de novo synthesis in Brucella-infected macrophages .
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Therapeutic Potential: Inhibitors targeting SHMT could disrupt one-carbon metabolism, but specificity for bacterial isoforms must be validated .
Product Specs
Target Background
KEGG: bmi:BMEA_A0804
