Date of Award

1-1-2017

Document Type

Thesis

Degree Name

M.S.

Department

Chemistry and Biochemistry

First Advisor

John A. Latham, Ph.D.

Keywords

Mechanism, Mycofactocin Pathway, Peptide Modification, Radical SAM Enzyme, SPASM Domain

Abstract

Mycofactocin is a putative peptide-derived redox cofactor in Mycobacterium family. Its putative biosynthetic pathway is encoded by the operon mftABCDEF. The initial step of this pathway is a posttranslational modification of a peptide precursor MftA, which is catalyzed by MftC enzyme. This modification only occurs in the presence of chaperone MftB. Here, we demonstrate that MftC is a radical S-adenosyl L-methionine (SAM) enzyme and we examine its catalytic mechanism. We show that the modification of MftA requires two equivalents of SAM and is implemented in two steps: (i) the decarboxylation of a C-terminal tyrosine, resulting in formation of an intermediate with a carbon-carbon double bond, and (ii) the cross-linking of the tyrosine with the penultimate valine, leading to formation of a cyclized product. We also show that MftC is able to modify unnatural peptide substrates, resulting in formation of specific and non-specific products.

Copyright Statement / License for Reuse

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Provenance

Received from ProQuest

Rights holder

Bulat Khaliullin

File size

68 p.

File format

application/pdf

Language

en

Discipline

Chemistry, Biochemistry

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