The conserved hypothetical protein Ca3427 exhibits the type 2 periplasmic-binding protein fold
This group includes the Ca3427 protein from candida albicans, which is an ortholog of Ttha1568 (MqnD) from Thermus thermophilies HB8, and other related hypothetical proteins. MqnD is an enzyme within an alternative menaquinone biosynthetic pathway that catalyzes the conversion of cyclic de-hypoxanthine futalosine to 1,4-dihydroxy-6-naphthoate. Menaquinone (MK; vitamin K) is an essential lipid-soluble carrier that shuttles electrons between membrane-bound protein complexes in the electron transport chain. Ca3427 has significant structural homology with the members of type 2 periplasmic-binding fold protein superfamily. The PBP2 proteins are typically comprised of two globular subdomains connected by a flexible hinge and bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap.
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