Crystal structure of OssO, a spirocyclase involved in the biosynthesis of ossamycin

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.219 
  • R-Value Observed: 0.222 

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This is version 1.2 of the entry. See complete history


Enzyme-Catalyzed Spiroacetal Formation in Polyketide Antibiotic Biosynthesis.

Bilyk, O.Oliveira, G.S.de Angelo, R.M.Almeida, M.O.Honorio, K.M.Leeper, F.J.Dias, M.V.B.Leadlay, P.F.

(2022) J Am Chem Soc 144: 14555-14563

  • DOI: https://doi.org/10.1021/jacs.2c03313
  • Primary Citation of Related Structures:  
    7SFN, 7SFP

  • PubMed Abstract: 

    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.

  • Organizational Affiliation

    Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Spirocyclase212Streptomyces ossamyceticusMutation(s): 0 
Gene Names: ossO
Find proteins for A0A481S8L7 (Streptomyces ossamyceticus)
Explore A0A481S8L7 
Go to UniProtKB:  A0A481S8L7
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A481S8L7
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.219 
  • R-Value Observed: 0.222 
  • Space Group: P 65 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 53.953α = 90
b = 53.953β = 90
c = 245.11γ = 120
Software Package:
Software NamePurpose
XDSdata reduction
Aimlessdata scaling
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Sao Paulo Research Foundation (FAPESP)Brazil18/00351-1
Sao Paulo Research Foundation (FAPESP)Brazil20/03850-9

Revision History  (Full details and data files)

  • Version 1.0: 2022-08-17
    Type: Initial release
  • Version 1.1: 2022-08-24
    Changes: Database references
  • Version 1.2: 2023-10-18
    Changes: Data collection, Refinement description