Derived structure of the putative sialic acid transporter from Escherichia coli predicts a novel sugar permease domain.
Catabolism of sialic acids by Escherichia coli requires the genes nanA and nanT, which were previously mapped between argG and rpoN (E.R. Vimr and F.A. Troy, J. Bacteriol. 164:845-853, 1985). This organization is confirmed and extended by physical mapping techniques. An open reading frame beginning 135 bp from the nanA translational stop codon could code for a 53,547-Da hydrophobic polypeptide predicted to contain 14 transmembrane segments. Complementation analysis confirmed that nanT is required for sialic acid uptake when expressed in trans. NanT is homologous to a putative permease encoded by open reading frame 425, which maps between leuX and fecE in the E. coli chromosome. However, unlike this hypothetical permease or previously reported monosaccharide transporters, NanT contains a centrally located domain with two additional potential membrane-spanning segments plus one amphiphilic alpha-helix that may be important for the structure and function of sialic acid-permease.
Martinez
J
J
Department of Microbiology, University of Illinois at Urbana-Champaign 61801, USA.
Steenbergen
S
S
Vimr
E
E
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D001692:Biological Transport; D050260:Carbohydrate Metabolism; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005816:Genetic Complementation Test; D008565:Membrane Proteins / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid; D016366:Open Reading Frames / Q000235:genetics; D027361:Organic Anion Transporters; D017433:Protein Structure, Secondary; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012794:Sialic Acids / Q000378:metabolism*; D027981:Symporters
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D027361:Organic Anion Transporters; D012794:Sialic Acids; D027981:Symporters; C096206:nanT protein, E coli; C421224:sialic acid transport proteins; D019158:N-Acetylneuraminic Acid