The bottromycin epimerase BotH defines a group of atypical α/β-hydrolase-fold enzymes

Abstract

The bottromycin epimerase BotH defines a group of atypical α/β-hydrolase-fold enzymes.

Identification of the peptide epimerase MslH responsible for d-amino acid introduction at the C-terminus of ribosomal peptides

“…S13A † ). The other is an α/β-hydrolase family enzyme (BotH) 22 that catalyzes epimerization at the C α of an Asp residue adjacent to a thiazolinyl group. In this case, the α-proton is acidic enough for spontaneous epimerization, albeit slowly, and BotH just enhances the epimerization by stabilizing the enamine intermediate (Fig.…”

New developments in RiPP discovery, enzymology and engineering

“…However, more recently BotH (equivalent to BmbG), an enzyme in the a/b hydrolase family that lacks the usual catalytic residues, was shown to carry out the epimerization reaction. 144 The enzyme acts prior to oxidative decarboxylation that converts the thiazoline at position 8 to a thiazole and also prior to methylation of the side chain of Asp7. Several crystal structures of the enzyme were reported resulting in a proposed mechanism in which the side chain of Asp7 may act as the base that deprotonates at its own Ca.…”

“…Recently, substrate assistance was also proposed for Asp epimerization during bottromycin biosynthesis (Section 5.1.3). 144…”

“…143 The a/b hydrolase BmbG was shown to be responsible for the epimerization of the Asp residue (Section 5.1.3). 144 3.7.1 Class-dening enzyme: macrolactamidine-installing YcaO. The YcaO superfamily members BmbD and BmbE (alternative naming: BotC and BotCD, respectively) were expected to catalyze the ATP-dependent activation of the peptide (Fig.…”

“…As macrolactamidine-forming YcaOs are not known to harbor RREs, studies then focused on understanding how these enzymes identify their substrates. Systematic C-terminal trimming of precursor peptides was performed, given that 143,144 In the first three steps, in no particular order, the N-terminal Met is removed by BmbK, thiazolines are installed by BmbD, and Val, Pro and Phe are C-methylated by BmbBF. Then the class-defining macrolactamidine is formed by BmbE, the follower peptide is removed by BmbH, and the Asp residue is epimerized by BmbG.…”