title: Functional characterization of a member of alanine or glycine: cation symporter family in halotolerant cyanobacterium Aphanothece halophytica.
abstract: Membrane proteins of amino acid-polyamine-organocation (APC) superfamily transport amino acids and amines across membranes and play important roles in the regulation of cellular processes. The alanine or glycine: cation symporter (AGCS) family belongs to APC superfamily and is found in prokaryotes, but its substrate specificity remains to be clarified. In this study, we found that a halotolerant cyanobacterium, Aphanothece halophytica has two putative ApagcS genes. The deduced amino acid sequence of one of genes, ApagcS1, exhibited high homology to Pseudomonas AgcS. The ApagcS1 gene was expressed in Escherichia coli JW4166 which is deficient in glycine uptake. Kinetics studies in JW4166 revealed that ApAgcS1 is a sodium-dependent glycine transporter. Competition experiments showed the significant inhibition by glutamine, asparagine, and glycine. The level of mRNA for ApagcS1 was induced by NaCl and nitrogen-deficient stresses. Uptake of glutamine by ApAgcS1 was also observed. Based on these data, the physiological role of ApAgcS1 was discussed.
authors.affiliation: a Graduate School of Environmental and Human Sciences , Meijo University , Nagoya , Japan.
authors.forename: Aporn
authors.initials: A
authors.lastname: Bualuang
authors.forename: Hakuto
authors.initials: H
authors.lastname: Kageyama
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Aran
authors.initials: A
authors.lastname: Incharoensakdi
authors.forename: Teruhiro
authors.initials: T
authors.lastname: Takabe
mesh_terms: D000409:Alanine / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005998:Glycine / Q000378:metabolism*; D050487:Glycine Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D009584:Nitrogen / Q000172:deficiency; D054712:Salinity; D012964:Sodium / Q000378:metabolism; D013312:Stress, Physiological; D013379:Substrate Specificity; D015854:Up-Regulation
chemical_list: D001426:Bacterial Proteins; D050487:Glycine Plasma Membrane Transport Proteins; D012964:Sodium; D009584:Nitrogen; D000409:Alanine; D005998:Glycine
keywords: alanine or glycine:cation symporter; amino acid uptake; halotolerant cyanobacteria; nitrogen deficient; salt stress