Phosphotransferase-mediated transport of the osmolyte 2-O-alpha-mannosyl-D-glycerate in Escherichia coli occurs by the product of the mngA (hrsA) gene and is regulated by the mngR (farR) gene product acting as repressor

J Biol Chem. 2004 Feb 13;279(7):5537-48. doi: 10.1074/jbc.M310980200. Epub 2003 Nov 25.


2-O-alpha-mannosyl-D-glycerate (MGs) has been recognized as an osmolyte in hyperthermophilic but not mesophilic prokaryotes. We report that MG is taken up and utilized as sole carbon source by Escherichia coli K12, strainMC4100. Uptake is mediated by the P-enolpyruvate-dependent phosphotransferase system with the MG-inducible HrsA (now called MngA) protein as its specific EIIABC complex. The apparent Km of MG uptake in induced cells was 10 microm, and the Vmax was 0.65 nmol/min/10(9) cells. Inverted membrane vesicles harboring plasmid-encoded MngA phosphorylated MG in a P-enolpyruvate-dependent manner. A deletion mutant in mngA was devoid of MG transport but is complemented by a plasmid harboring mngA. Uptake of MG in MC4100 also caused induction of a regulon specifying the uptake and the metabolism of galactarate and glucarate controlled by the CdaR activator. The ybgG gene (now called mngB) the gene immediately downstream of mngA encodes a protein with alpha-mannosidase activity. farR, the gene upstream of mngA (now called mngR) had previously been characterized as a fatty acyl-responsive regulator; however, deletion of mngR resulted in the up-regulation of only two genes, mngA and mngB. The mngR deletion caused constitutive MG transport that became MG-inducible after transformation with plasmid expressed mngR. Thus, MngR is the regulator (repressor) of the MG transport/metabolism system. Thus, the mngR mngA mngB gene cluster encodes an MG utilizing system.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Biological Transport
  • Chromatography, Thin Layer
  • Cloning, Molecular
  • DNA Transposable Elements
  • DNA-Binding Proteins / metabolism*
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / metabolism*
  • Gene Deletion
  • Genome, Bacterial
  • Glycolipids / chemistry*
  • Kinetics
  • Models, Biological
  • Models, Chemical
  • Models, Genetic
  • Molecular Sequence Data
  • Multigene Family
  • Mutagenesis, Site-Directed
  • Mutation
  • Oligonucleotide Array Sequence Analysis
  • Phosphorylation
  • Phosphotransferases / metabolism*
  • Plasmids / metabolism
  • Promoter Regions, Genetic
  • Time Factors
  • Transcription Factors / metabolism*
  • Up-Regulation
  • alpha-Mannosidase / metabolism
  • beta-Galactosidase / metabolism


  • 2-O-mannosylglycerate
  • DNA Transposable Elements
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Glycolipids
  • Transcription Factors
  • mngR protein, E coli
  • Phosphotransferases
  • beta-Galactosidase
  • alpha-Mannosidase