Recombinant Geobacillus thermodenitrificans Succinyl-CoA ligase [ADP-forming] subunit beta (sucC)
Description
Introduction to Succinyl-CoA Ligase and Its Subunits
Succinyl-CoA ligase (SCS) is a mitochondrial enzyme critical to the tricarboxylic acid (TCA) cycle, catalyzing the reversible conversion of succinyl-CoA to succinate while generating ATP or GTP. This enzyme consists of two subunits:
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α-subunit (sucD): Binds CoA and forms a phosphohistidine intermediate.
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β-subunit (sucC): Determines nucleotide specificity (ADP or GDP) .
In Geobacillus thermodenitrificans, a thermophilic bacterium, the ADP-forming β-subunit (sucC) plays a role in energy metabolism under high-temperature conditions. Recombinant expression of this subunit enables biochemical and industrial applications .
Catalytic Mechanism
The enzyme operates via a two-step process:
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Phosphorylation: Succinyl-CoA transfers its CoA moiety to a histidine residue on the α-subunit.
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Nucleotide Binding: The β-subunit binds ADP, enabling phosphoryl transfer to form ATP .
Host Strains and Vectors
Optimization Strategies
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Methylation Control: Use of dam mutant E. coli plasmids improves transformation efficiency in Geobacillus spp. by bypassing restriction-modification systems .
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Promoter Engineering: Strong promoters like Pgrac and pcj1 enhance expression levels in thermophilic hosts .
Industrial Relevance
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Thermostable Enzyme Production: Recombinant sucC is used in biocatalysis at high temperatures, such as in biofuel synthesis .
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Metabolic Engineering: Co-expression with TCA cycle enzymes improves ATP yield in synthetic pathways .
Research Findings
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Redox Homeostasis: In cancer studies, human SUCLA2 (a homolog) regulates stress granules to mitigate oxidative stress, suggesting analogous roles in bacterial systems .
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Substrate Specificity: Geobacillus sucC shows preference for ADP over GDP, unlike its GTP-specific counterparts in other species .
Limitations
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Structural Dynamics: The phosphohistidine loop’s movement between catalytic sites remains poorly characterized .
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Heterologous Expression: Low yields in non-thermophilic hosts (e.g., E. coli) necessitate strain-specific optimization .
Emerging Opportunities
Product Specs
Target Background
KEGG: gtn:GTNG_1061
STRING: 420246.GTNG_1061
