Recombinant Campylobacter lari Phosphoserine aminotransferase (serC)
Description
Functional Role of SerC in Campylobacter
SerC catalyzes the conversion of 3-phosphoserine to L-serine in the phosphorylated pathway of serine biosynthesis. In C. jejuni, serine auxotrophy is circumvented via de novo synthesis using SerC, which is essential for survival under sulfur-limited conditions . C. lari shares metabolic constraints with C. jejuni, including deficiencies in amino acid biosynthesis pathways . Genomic analyses reveal that C. lari lacks citrate synthase and other TCA cycle enzymes, heightening reliance on amino acid uptake or synthesis . While direct evidence for SerC in C. lari is sparse, homologs of serC are present in related Campylobacter species, suggesting conserved functionality .
Recombinant SerC Expression in Campylobacter
Recombinant SerC production has been optimized in C. jejuni subsp. doylei using plasmid-based systems. Key steps include:
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Cloning: The serC gene (UniProt: A7H543) is cloned into pET32 vectors with thioredoxin and hexahistidine tags for solubility and purification .
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Expression: Induced in E. coli BL21(DE3) at 18°C with 0.4 mM IPTG, yielding ~36 kDa fusion proteins .
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Purification: Refolded via urea gradient chromatography on HisTrap columns, achieving >85% purity (SDS-PAGE) .
Table 1: Recombinant SerC Expression Parameters
| Parameter | Details |
|---|---|
| Host Strain | E. coli BL21(DE3) |
| Plasmid | pET32 with thioredoxin/His-tag |
| Induction | 0.4 mM IPTG, 18°C |
| Purification | Ni-NTA affinity chromatography, urea gradient refolding |
| Purity | >85% (SDS-PAGE) |
| Storage | -20°C long-term; -80°C for extended stability |
Data derived from C. jejuni subsp. doylei studies .
Genomic and Metabolic Context in C. lari
Comparative genomics of the C. lari group highlights:
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Synteny: Strong genomic conservation with C. jejuni, including flagellar glycosylation and virulence gene clusters .
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Amino Acid Biosynthesis: Deficiencies in pathways (e.g., cysteine, serine) necessitate environmental scavenging .
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Virulence Linkages: C. lari subsp. lari encodes adhesion factors and carbohydrate-modifying enzymes, potentially linked to serine metabolism .
Notably, C. lari urease-positive thermotolerant Campylobacter (UPTC) strains exhibit reduced serine dehydratase activity compared to C. jejuni, implying divergent metabolic strategies .
Research Gaps and Future Directions
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Functional Characterization: No studies have directly expressed or purified C. lari SerC. Homology modeling using C. jejuni SerC (87% sequence identity) could guide experimental validation.
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Metabolic Flux Analysis: Isotopic tracing could clarify serine’s role in C. lari’s adaptation to marine and avian niches .
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Diagnostic Applications: Recombinant SerC from C. jejuni reacts with host antibodies in ELISA ; similar studies in C. lari could advance serodiagnostics.
Product Specs
Target Background
KEGG: cla:Cla_1350
STRING: 306263.Cla_1350
