Investigating β-hydroxyenduracididine formation in the biosynthesis of the mannopeptimycins

The mannopeptimycins (MPPs) are potent glycopeptide antibiotics that contain both D and L forms of the unique, arginine-derived amino acid beta-hydroxyenduracididine (beta hEnd). The product of the mppO gene in the MPP biosynthetic cluster resembles several non-heme iron, alpha-ketoglutarate-dependent oxygenases, such as VioC and clavaminate synthase. The role of MppO in beta hEnd biosynthesis was confirmed through inactivation of mppO, which yielded a strain that produced dideoxy-MPPs; indicating that mppO is essential for generating the beta-hydroxy functionality for both beta hEnd residues. Characterization in vitro of recombinant His(6)-MppO expressed in E. coli revealed that MppO selectively hydroxylates the beta carbon of free L-enduracididine.