This entry represents the N-terminal domain of CntK, a cofactor-independent histidine racemase that catalyzes the conversion of L-histidine to D-histidine [1]. This domain is part of the enzyme involved in the first step of staphylopine biosynthesis, ...
This entry represents the N-terminal domain of CntK, a cofactor-independent histidine racemase that catalyzes the conversion of L-histidine to D-histidine [1]. This domain is part of the enzyme involved in the first step of staphylopine biosynthesis, with D-histidine serving as an essential building block for this metallophore [1,4]. The domain contains one of the two conserved cysteine residues (Cys72) required for the two-base catalytic mechanism [1]. The N-terminal domain contributes to dimerization, with beta-sheets from two monomers aligning and forming main chain hydrogen bonds that stabilize the homodimer [1]. This domain consists of residues 1-119 plus a few residues at the C-terminus (residues 262-273) [1]. It adopts a DapF-like fold and contains residues involved in substrate recognition, including Asn16 and Glu46, which are important for binding the imidazole group of histidine [1]. This catalytic activity is linked to bacterial virulence by enhancing survival in metal-limited environments, and structural studies reveal a conserved overall fold with key catalytic cysteine residues despite low sequence similarity to other racemases [2-4].
