Coenzyme B12-dependent glutamate mutase epsilon subunit-like family; contains proteins similar to Clostridium cochlearium glutamate mutase (Glm) and Streptomyces tendae Tu901 NikV. Glm catalyzes a carbon-skeleton rearrangement of L-glutamate to L-threo-3-methylaspartate. The first step in the catalysis is a homolytic cleavage of the Co-C bond of the coenzyme B12 cofactor to generate a 5'-deoxyadenosyl radical. This radical then initiates the rearrangement reaction. C. cochlearium Glm is a sigma2epsilon2 heterotetramer. Glm plays a role in glutamate fermentation in Clostridium sp. and in members of the family Enterobacteriaceae, and in the synthesis of the lipopeptide antibiotic friulimicin in Actinoplanes friuliensis. S. tendae Tu901 glutamate mutase-like proteins NikU and NIkV participate in the synthesis of the peptidyl nucleoside antibiotic nikkomycin. NikU and NikV proteins have sequence similarity to Clostridium Glm sigma and epsilon components respectively, and may catalyze the rearrangement of 2-oxoglutaric acid to 2-keto-3-methylsuccinic acid during nikkomycin synthesis.
Feature 1:B12 cofactor binding site [chemical binding site]
Evidence:
Structure:1CCW; Clostridium cochlearium glutamate mutase heterotetramer bound with coenzyme B12 cofactors; contacts at 3.5A.
Comment:C. cochlearium GLM consists of a heterotetramer (a dimer of heterodimers) of 2 sigma and 2 epsilon subunits with one coenzyme B12 cofactor bound at each sigma-epsilon interface.
Jiyao W et al.(2023). "The conserved domain database in 2023.",