S165: Structural and Functional Studies of Novel Thiazole/Oxazole-Modified Microcins

Chemical and biological approaches have uncovered a novel family of
natural products. The hallmark of this family is thiazole and
(methyl)oxazole heterocyles, which are derived from Cys and Ser/Thr
residues of a ribosomally produced precursor peptide. To date, we have
identified >350 orthologous biosynthetic gene clusters that produce
such compounds, now termed the thiazole/oxazole-modified microcins
(TOMMs). During TOMM biosynthesis, the unstructured, inactive
precursor peptide is converted to a biologically active compound by
the action of a trimeric synthetase complex. First, a cyclodehydratase
catalyzes the formation of azolines from Cys/Ser/Thr with consumption
of ATP. To be catalytically active, the cyclodehydratase requires the
presence of a scaffolding/regulatory partner, termed the docking
protein. In a second reaction, a dehydrogenase oxidizes the azoline
heterocycle to afford the corresponding azole. This talk focuses on
the development of novel assays our lab employs to probe the
mechanistic enzymology of the TOMM cyclodehydratase.