Type III Pyridoxal 5-phosphate (PLP)-Dependent Enzymes, Proteobacterial Alanine Racemases
This subfamily is composed mainly of proteobacterial alanine racemases (EC 5.1.1.1), fold type III PLP-dependent enzymes that catalyze the interconversion between L- and D-alanine, which is an essential component of the peptidoglycan layer of bacterial cell walls. hese proteins are similar to other bacterial ARs and are fold type III PLP-dependent enzymes containing contains an N-terminal PLP-binding TIM-barrel domain and a C-terminal beta-sandwich domain. They exist as homodimers with active sites that lie at the interface between the TIM barrel domain of one subunit and the beta-sandwich domain of the other subunit. Homodimer formation and the presence of the PLP cofactor are required for catalytic activity.
Comment:The active site is composed of residues from both subunits of the dimer. There are two active sites in the functional dimer. Only one subunit of the dimer is shown in the 1RCQ structure.
Structure:1RCQ_A; Pseudomonas aeruginosa alanine racemase binds PLP and a guest substrate (D-lysine); defined at 4A contacts.
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