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An unprecedented mechanism of nucleotide methylation in organisms containing thyX.

ABSTRACT: In several human pathogens, thyX-encoded flavin-dependent thymidylate synthase (FDTS) catalyzes the last step in the biosynthesis of thymidylate, one of the four DNA nucleotides. ThyX is absent in humans, rendering FDTS an attractive antibiotic target; however, the lack of mechanistic understanding prohibits mechanism-based drug design. Here, we report trapping and characterization of two consecutive intermediates, which together with previous crystal structures indicate that the enzyme's reduced flavin relays a methylene from the folate carrier to the nucleotide acceptor. Furthermore, these results corroborate an unprecedented activation of the nucleotide that involves no covalent modification but only electrostatic polarization by the enzyme's active site. These findings indicate a mechanism that is very different from thymidylate biosynthesis in humans, underscoring the promise of FDTS as an antibiotic target.

SUBMITTER: Mishanina TV

PROVIDER: S-EPMC4744818 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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An unprecedented mechanism of nucleotide methylation in organisms containing thyX.

Mishanina Tatiana V TV Yu Liping L Karunaratne Kalani K Mondal Dibyendu D Corcoran John M JM Choi Michael A MA Kohen Amnon A

Science (New York, N.Y.) 20160101 6272

In several human pathogens, thyX-encoded flavin-dependent thymidylate synthase (FDTS) catalyzes the last step in the biosynthesis of thymidylate, one of the four DNA nucleotides. ThyX is absent in humans, rendering FDTS an attractive antibiotic target; however, the lack of mechanistic understanding prohibits mechanism-based drug design. Here, we report trapping and characterization of two consecutive intermediates, which together with previous crystal structures indicate that the enzyme's reduce ...[more]

PMID: 26823429

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An unusual mechanism of thymidylate biosynthesis in organisms containing the thyX gene.

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