posted on 2016-11-10, 00:00authored byMarina Serebryakova, Darya Tsibulskaya, Olga Mokina, Alexey Kulikovsky, Manesh Nautiyal, Arthur Van Aerschot, Konstantin Severinov, Svetlana Dubiley
Microcin
C and related antibiotics are Trojan-horse peptide-adenylates.
The peptide part is responsible for facilitated transport inside the
sensitive cell, where it gets processed to release a toxic warheada
nonhydrolyzable aspartyl-adenylate, which inhibits aspartyl-tRNA synthetase.
Adenylation of peptide precursors is carried out by MccB THIF-type
NAD/FAD adenylyltransferases. Here, we describe a novel microcin C-like
compound from Bacillus amyloliquefaciens. The B. amyloliquefaciens MccB demonstrates an unprecedented
ability to attach a terminal cytidine monophosphate to cognate precursor
peptide in cellular and cell free systems. The cytosine moiety undergoes
an additional modificationcarboxymethylationthat is
carried out by the C-terminal domain of MccB and the MccS enzyme that
produces carboxy-SAM, which serves as a donor of the carboxymethyl
group. We show that microcin C-like compounds carrying terminal cytosines
are biologically active and target aspartyl-tRNA synthetase, and that
the carboxymethyl group prevents resistance that can occur due to
modification of the warhead. The results expand the repertoire of
known enzymatic modifications of peptides that can be used to obtain
new biological activities while avoiding or limiting bacterial resistance.