In vitro analysis of carboxyacyl substrate tolerance in the loading and first extension modules of borrelidin polyketide synthase.

Biochemistry

Department of Plant and Microbial Biology, ‡Department of Chemical and Biomolecular Engineering, §Department of Chemistry, ∥QB3 Institute, and ⊥Department of Bioengineering, University of California, Berkeley, California 94270, United States.

Published: September 2014

The borrelidin polyketide synthase (PKS) begins with a carboxylated substrate and, unlike typical decarboxylative loading PKSs, retains the carboxy group in the final product. The specificity and tolerance of incorporation of carboxyacyl substrate into type I PKSs have not been explored. Here, we show that the first extension module is promiscuous in its ability to extend both carboxyacyl and non-carboxyacyl substrates. However, the loading module has a requirement for substrates containing a carboxy moiety, which are not decarboxylated in situ. Thus, the loading module is the basis for the observed specific incorporation of carboxylated starter units by the borelidin PKS.

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http://dx.doi.org/10.1021/bi500951cDOI Listing

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