MvaB is a hydroxymethylglutaryl-CoA lyase that cleaves (S)-3-hydroxy-3-methylglutaryl-CoA to acetoacetate and acetyl-CoA. This shared terminal reaction can receive HMG-CoA from distal L-leucine catabolism and from other degradative pathways.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | MODIFY | Summary: Generic catalytic activity is redundant with the exact lyase term. Reason: Replace the generic catalytic term with the substrate-specific HMG-CoA lyase activity. Proposed replacements: hydroxymethylglutaryl-CoA lyase activity |
| GO:0004419 hydroxymethylglutaryl-CoA lyase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Correct enzyme-specific molecular function. Reason: The UniProt catalytic reaction explicitly cleaves HMG-CoA to acetoacetate and acetyl-CoA. |
| GO:0006552 L-leucine catabolic process | IEA GO_REF:0000118 | ACCEPT | Summary: Plausible terminal role in distal L-leucine catabolism. Reason: The HMG-CoA lyase reaction consumes the product of LiuC. |
| GO:0016833 oxo-acid-lyase activity | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Oxo-acid lyase activity is a broad parent term. Reason: This is a valid parent activity, while the substrate-specific HMG-CoA lyase activity captures the core function. |
| GO:0046872 metal ion binding | ISS PMID:16330546 Crystal structures of two bacterial 3-hydroxy-3-methylglutar... | NEW | Summary: HMG-CoA lyases are DRE-TIM metallolyases with a conserved divalent-cation site. Reason: A divalent cation is a mechanistic requirement of the family, although the preferred ion has not been measured for Q88H25. Supporting Evidence: PMID:16330546 the catalytic center contains a divalent cation-binding site formed by a cluster of invariant residues that cap the core of the barrel file:PSEPK/mvaB/mvaB-uniprot.txt Metal-binding |
| GO:0046951 ketone body biosynthetic process | IEA GO_REF:0000118 | MARK AS OVER ANNOTATED | Summary: The reaction produces acetoacetate, but that product alone does not establish a dedicated ketone-body biosynthetic process. Reason: This product-derived process annotation overstates the physiological context; retain the experimentally supported leucine catabolic process instead. |
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Download this section (compressed HTML)Q: How is mvaB expression coordinated with the physically separated ivd-mccB-liuC-mccA cluster during growth on leucine or isovalerate?
Experiment: Measure HMG-CoA cleavage by purified MvaB across Mg2+, Mn2+, and metal-chelated conditions, and compare leucine growth phenotypes of mvaB, PP_3394, and double deletions.
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