Beilstein J. Org. Chem.2017,13, 2408–2415, doi:10.3762/bjoc.13.238
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
, 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.
Keywords: amidinohydrolase; clethramycin; mediomycin; polyketide synthase; sulfotransferase; Introduction
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Graphical Abstract
Scheme 1:
The structures of clethramycin, mediomycins and related linear polyenes.