期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：49
页码：14037-14042
DOI：10.1073/pnas.1609869113
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceThe cyanobactin prenyltransferases serve as a tool kit for regioselective and chemoselective peptide and protein modifications, in which each enzyme can catalyze the same chemistry on an enormous number of different substrates. Installation of a minimal motif is sufficient to direct modifications on any peptide substrate, which can alter their properties to be more drug-like. The cyanobactin prenyltransferases catalyze a series of known or unprecedented reactions on millions of different substrates, with no easily observable recognition motif and exquisite regioselectivity. Here we define the basis of broad substrate tolerance for the otherwise uncharacterized TruF family. We determined the structures of the Tyr-prenylating enzyme PagF, in complex with an isoprenoid donor analog and a panel of linear and macrocyclic peptide substrates. Unexpectedly, the structures reveal a truncated barrel fold, wherein binding of large peptide substrates is necessary to complete a solvent-exposed hydrophobic pocket to form the catalytically competent active site. Kinetic, mutational, chemical, and computational analyses revealed the structural basis of selectivity, showing a small motif within peptide substrates that is sufficient for recognition by the enzyme. Attaching this 2-residue motif to two random peptides results in their isoprenylation by PagF, demonstrating utility as a general biocatalytic platform for modifications on any peptide substrate.
