Genetics of the glutamate-mediated methylamine utilization pathway in the facultative methylotrophic beta-proteobacterium Methyloversatilis universalis FAM5

Mol Microbiol. 2010 Jan;75(2):426-39. doi: 10.1111/j.1365-2958.2009.06989.x. Epub 2009 Nov 25.

Abstract

The ability of some microbial species to oxidize monomethylamine via glutamate-mediated pathways was proposed in the 1960s; however, genetic determinants of the pathways have never been described. In the present study we describe a gene cluster essential for operation of the N-methylglutamate pathway in the methylotrophic beta-proteobacterium Methyloversatilis universalis FAM5. Four major polypeptides from protein fractions displaying high activities of N-methylglutamate synthetase, N-methylglutamate dehydrogenase and gamma-glutamylmethylamide synthetase were selected for mass spectrometry-based identification. The activities of enzymes were associated with the presence of peptides identified as ferredoxin-dependent glutamate synthase (GltB2), large subunit of putative heterotetrameric sarcosine oxidase (SoxA) and glutamine synthetase type III (GSIII) respectively. A gene cluster (8.3 kb) harbouring gltB2, soxA and gsIII-like genes was amplified from M. universalis FAM5, sequenced and assembled. Two partial and six complete open reading frames arranged in the order soxBDAG-gsIII-gltB132 were identified and subjected to mutational analysis, functional and metabolic profiling. We demonstrated that gltB-like and sox-like genes play a key role in methylamine utilization and encode N-methylglutamate synthetase and N-methylglutamate dehydrogenase respectively. Metabolic, enzymatic and mutational analyses showed that the gsIII-like gene encodes gamma-glutamylmethylamide synthetase; however, this enzyme is not essential for oxidation of methylamine.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alanine / metabolism
  • Bacterial Proteins / genetics
  • Betaproteobacteria / drug effects
  • Betaproteobacteria / genetics*
  • Betaproteobacteria / growth & development
  • Betaproteobacteria / metabolism
  • DNA Mutational Analysis / methods
  • Gene Expression Profiling / methods
  • Glutamate Synthase / genetics
  • Glutamate Synthase / metabolism
  • Glutamic Acid / genetics
  • Glutamic Acid / metabolism*
  • Glutamic Acid / pharmacology
  • Glutamine / metabolism
  • Kinetics
  • Methylamines / metabolism*
  • Multigene Family
  • Open Reading Frames
  • Oxidation-Reduction
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism

Substances

  • Bacterial Proteins
  • Methylamines
  • Peptide Fragments
  • Glutamine
  • Glutamic Acid
  • methylamine
  • Glutamate Synthase
  • Alanine