Citrullination Inactivates Nicotinamide-N-methyltransferase

Venkatesh V. Nemmara, Ronak Tilvawala, Ari J. Salinger, Lacey Miller, Son Hong Nguyen, Eranthie Weerapana, Paul R. Thompson

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19 Scopus citations


Nicotinamide-N-methyltransferase (NNMT) catalyzes the irreversible methylation of nicotinamide (NAM) to form N-methyl nicotinamide using S-adenosyl methionine as a methyl donor. NNMT is implicated in several chronic disease conditions, including cancers, kidney disease, cardiovascular disease, and Parkinson's disease. Although phosphorylation of NNMT in gastric tumors is reported, the functional effects of this post-translational modification has not been investigated. We previously reported that citrullination of NNMT by Protein Arginine Deiminases abolished its methyltransferase activity. Herein, we investigate the mechanism of inactivation. Using tandem mass spectrometry, we identified three sites of citrullination in NNMT. With this information in hand, we used a combination of site-directed mutagenesis, kinetics, and circular dichoism experiments to demonstrate that citrullination of R132 leads to a structural perturbation that ultimately promotes NNMT inactivation.

Original languageEnglish (US)
Pages (from-to)2663-2672
Number of pages10
JournalACS Chemical Biology
Issue number9
StatePublished - Sep 21 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Medicine


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