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Sulfation and amidinohydrolysis in the biosynthesis of giant linear polyenes.

Published version
Peer-reviewed

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Authors

Hong, Hui 
Samborskyy, Markiyan  ORCID logo  https://orcid.org/0000-0002-6946-0385
Usachova, Katsiaryna 
Schnatz, Katharina 
Leadlay, Peter F 

Abstract

Clethramycin from Streptomyces malaysiensis DSM4137, and mediomycins (produced together with clethramycin from Streptomyces mediocidicus), are near-identical giant linear polyenes apparently constructed from, respectively, a 4-guanidinobutanoate or 4-aminobutanoate starter unit and 27 polyketide extender units, and bearing a specific O-sulfonate modification at the C-29 hydroxy group. We show here that mediomycins are actually biosynthesised not by use of a different starter unit but by direct late-stage deamidination of (desulfo)clethramycin. A gene (slf) encoding a candidate sulfotransferase has been located in both gene clusters. Deletion of this gene in DSM4137 led to accumulation of desulfoclethramycin only, instead of a mixture of desulfoclethramycin and clethramycin. The mediomycin gene cluster does not encode an amidinohydrolase, but when three candidate amidinohydrolase genes from elsewhere in the S. mediocidicus genome were individually expressed in Escherichia coli and assayed, only one of them (medi4948), located 670 kbp away from the mediomycin gene cluster on the chromosome, catalysed the removal of the amidino group from desulfoclethramycin. Subsequent cloning of medi4948 into DSM4137 caused mediomycins A and B to accumulate at the expense of clethramycin and desulfoclethramycin, respectively, a rare case where an essential biosynthetic gene is not co-located with other pathway genes. Clearly, both desulfoclethramycin and clethramycin are substrates for this amidinohydrolase. Also, purified recombinant sulfotransferase from DSM4137, in the presence of 3'-phosphoadenosine-5'-phosphosulfate as donor, efficiently converted mediomycin B to mediomycin A in vitro. Thus, in the final steps of mediomycin A biosynthesis deamidination and sulfotransfer can take place in either order.

Description

Keywords

amidinohydrolase, clethramycin, mediomycin, polyketide synthase, sulfotransferase

Journal Title

Beilstein J Org Chem

Conference Name

Journal ISSN

1860-5397
1860-5397

Volume Title

13

Publisher

Beilstein Institut
Sponsorship
European Commission (276015)
The Royal Society (wm130101)
BBSRC (via University of Warwick) (RCHGC3013)
Biotechnology and Biological Sciences Research Council (BB/M012158/1)