Crystal structures of monkey and mouse nicotinamide N-methyltransferase (NNMT) bound with end product, 1-methyl nicotinamide

Biochem Biophys Res Commun. 2017 Sep 16;491(2):416-422. doi: 10.1016/j.bbrc.2017.07.087. Epub 2017 Jul 15.

Abstract

Nicotinamide N-methyltransferase (NNMT) is a S-adenosyl-l-methionine (SAM)-dependent enzyme that catalyzes N-methylation of nicotinamide (NA) and other pyridines to form N-methyl pyridinium ions. Here we report the first ternary complex X-ray crystal structures of monkey NNMT and mouse NNMT in bound form with the primary endogenous product, 1-methyl nicotinamide (MNA) and demethylated cofactor, S-adenosyl-homocysteine (SAH) determined at 2.30 Å and 1.88 Å respectively. The structural fold of these enzymes is identical to human NNMT. It is known that the primary endogenous product catalyzed by NNMT, MNA is a specific inhibitor of NNMT. Our data clearly indicates that the MNA binds to the active site and it would be trapped in the active site due to the formation of the bridge between the pole (long helix, α3) and long C-terminal loop. This might explain the mechanism of MNA acting as a feedback inhibitor of NNMT.

Keywords: Feedback inhibition; MNA; NA; NNMT; Ternary complex.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Catalytic Domain
  • Cloning, Molecular
  • Crystallography, X-Ray
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Feedback, Physiological*
  • Gene Expression
  • Macaca mulatta
  • Mice
  • Models, Molecular
  • Niacinamide / analogs & derivatives*
  • Niacinamide / chemistry
  • Niacinamide / metabolism
  • Nicotinamide N-Methyltransferase / antagonists & inhibitors
  • Nicotinamide N-Methyltransferase / chemistry*
  • Nicotinamide N-Methyltransferase / genetics
  • Nicotinamide N-Methyltransferase / metabolism
  • Protein Binding
  • Protein Conformation, alpha-Helical
  • Protein Conformation, beta-Strand
  • Protein Interaction Domains and Motifs
  • Protein Structure, Tertiary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • S-Adenosylmethionine / chemistry*
  • S-Adenosylmethionine / metabolism
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Substrate Specificity

Substances

  • Recombinant Proteins
  • Niacinamide
  • S-Adenosylmethionine
  • Nicotinamide N-Methyltransferase
  • N(1)-methylnicotinamide