7SFP image
Entry Detail
PDB ID:
7SFP
Keywords:
Title:
Crystal structure of OssO, a spirocyclase involved in the biosynthesis of ossamycin
Biological Source:
PDB Version:
Deposition Date:
2021-10-04
Release Date:
2022-08-17
Method Details:
Experimental Method:
Resolution:
2.20 Å
R-Value Free:
0.27
R-Value Work:
0.21
R-Value Observed:
0.22
Space Group:
P 65 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Spirocyclase
Chain IDs:A
Chain Length:212
Number of Molecules:1
Biological Source:Streptomyces ossamyceticus
Primary Citation
Enzyme-Catalyzed Spiroacetal Formation in Polyketide Antibiotic Biosynthesis.
J.Am.Chem.Soc. 144 14555 14563 (2022)
PMID: 35921248 DOI: 10.1021/jacs.2c03313

Abstact

A key step in the biosynthesis of numerous polyketides is the stereospecific formation of a spiroacetal (spiroketal). We report here that spiroacetal formation in the biosynthesis of the macrocyclic polyketides ossamycin and oligomycin involves catalysis by a novel spiroacetal cyclase. OssO from the ossamycin biosynthetic gene cluster (BGC) is homologous to OlmO, the product of an unannotated gene from the oligomycin BGC. The deletion of olmO abolished oligomycin production and led to the isolation of oligomycin-like metabolites lacking the spiroacetal structure. Purified OlmO catalyzed complete conversion of the major metabolite into oligomycin C. Crystal structures of OssO and OlmO reveal an unusual 10-strand β-barrel. Three conserved polar residues are clustered together in the β-barrel cavity, and site-specific mutation of any of these residues either abolished or substantially diminished OlmO activity, supporting a role for general acid/general base catalysis in spiroacetal formation.

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