Open AccessComplete Reconstitution and Deorphanization of the 3 MDa Nocardiosis-Associated Polyketide Synthase
Author(s) -
Kai P. Yuet,
Corey W. Liu,
Stephen R. Lynch,
James Kuo,
Wesley Michaels,
Robert B. Lee,
Abigail E. McShane,
Brian L. Zhong,
Curt R. Fischer,
Chaitan Khosla
Publication year - 2020
Publication title -
journal of the american chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.115
H-Index - 612
eISSN - 1520-5126
pISSN - 0002-7863
DOI - 10.1021/jacs.0c00904
Subject(s) - polyketide synthase , polyketide , aglycone , chemistry , nocardia , epothilones , stereochemistry , biochemistry , enzyme , biosynthesis , biology , bacteria , genetics , glycoside
Several Nocardia strains associated with nocardiosis, a potentially life-threatening disease, house a nonamodular assembly line polyketide synthase (PKS) that presumably synthesizes an unknown polyketide. Here, we report the discovery and structure elucidation of the NOCAP (nocardiosis-associated polyketide) aglycone by first fully reconstituting the NOCAP synthase in vitro from purified protein components followed by heterologous expression in E. coli and spectroscopic analysis of the purified products. The NOCAP aglycone has an unprecedented structure comprised of a substituted resorcylaldehyde headgroup linked to a 15-carbon tail that harbors two conjugated all- trans trienes separated by a stereogenic hydroxyl group. This report is the first example of reconstituting a trans -acyltransferase assembly line PKS in vitro and of using these approaches to "deorphanize" a complete assembly line PKS identified via genomic sequencing. With the NOCAP aglycone in hand, the stage is set for understanding how this PKS and associated tailoring enzymes confer an advantage to their native hosts during human Nocardia infections.