Biosynthesis of Glidomides and Elucidation of Different Mechanisms for Formation of ß-OH Amino Acid Building Blocks.

ABSTRACT

Nonribosomal peptide synthetases (NRPSs) can incorporate nonproteinogenic amino acids into peptidyl backbones to increase structural diversity. Genome mining of Schlegelella brevitalea led to the identification of a class of linear lipoheptapeptides, glidomides, featuring two unusual residues threo-ß-OH-L-His and threo-ß-OH-D-Asp. The ß-hydroxylation of Asp and His is catalyzed by the nonheme FeII /α-ketoglutarate-dependent ß-hydroxylases GlmD and GlmF, respectively. GlmD independently catalyzes the hydroxylation of L-Asp to primarily produce threo-ß-OH-L-Asp on the thiolation domain, and then undergoes epimerization to form threo-ß-OH-D-Asp in the final products. However, ß-hydroxylation of His requires the concerted action of GlmF and the interface (I) domain, a novel condensation domain family clade. The key sites of I domain for interaction with GlmF were identified, suggesting that the mechanism for hydroxylation of His depends on the collaboration between hydroxylase and NRPS.