Publication Date:
2022-05-26
Description:
Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of United States of America 113 (2016): 3797-3802, doi: 10.1073/pnas.1519695113.
Description:
Halogenated pyrroles (halopyrroles) are common chemical moieties found in bioactive bacterial natural products. The halopyrrole moieties of mono- and di- halopyrrole-containing compounds arise from a conserved mechanism in which a proline-derived pyrrolyl group bound to a carrier protein is first halogenated then elaborated by peptidic or polyketide extensions. This paradigm is broken during the marine pseudoalteromonad bacterial biosynthesis of the coral larval settlement cue tetrabromopyrrole (1), which arises from the substitution of the proline-derived carboxylate by a bromine atom. To understand the molecular basis for decarboxylative bromination in the biosynthesis of 1, we sequenced two Pseudoalteromonas genomes and identified a conserved four-gene locus encoding the enzymes involved its complete biosynthesis. Through total in vitro reconstitution of the biosynthesis of 1 using purified enzymes and biochemical interrogation of individual biochemical steps, we show that all four bromine atoms in 1 are installed by the action of a single flavin-dependent halogenase- Bmp2. Tetrabromination of the pyrrole induces a thioesterase-mediated offloading reaction from the carrier protein and activates the biosynthetic intermediate for decarboxylation. Insights into the tetrabrominating activity of Bmp2 were obtained from the high-resolution crystal structure of the halogenase contrasted against structurally homologous halogenase Mpy16 that forms only a dihalogenated pyrrole in marinopyrrole biosynthesis. Structure-guided mutagenesis of the proposed substrate-binding pocket of Bmp2 led to a reduction in the degree of halogenation catalyzed. Our study provides a biogenetic basis for the biosynthesis of 1, and sets a firm foundation for querying the biosynthetic potential for the production of 1 in marine (meta)genomes.
Description:
This work was jointly supported by the US National Science Foundation (OCE-1313747) and the US National Institute of Environmental Health Sciences (P01-ES021921) through the Ocean and Human Health Program to B.S.M., and the US National Institute of Allergy and Infectious Disease R01-AI47818 to B.S.M. and R21-
AI119311 to K.E.W. and T.J.M., the Mote Protect Our Reef Grant Program (POR-2012-3), the Dart Foundation, the Smithsonian Competitive Grants Program for Science to V.J.P., the Howard Hughes Medical Institute to J.P.N., the US National Institutes of Health (NIH) Marine Biotechnology Training Grant predoctoral fellowship to A.E. (T32-GM067550), the Helen Hay Whitney Foundation postdoctoral fellowship to V.A., and a Swiss National Science Foundation (SNF) postdoctoral Fellowship to S.D.
Description:
2016-09-21
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
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