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
(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
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.