title: The solute specificity profiles of nucleobase cation symporter 1 (NCS1) from Zea mays and Setaria viridis illustrate functional flexibility.
abstract: The solute specificity profiles (transport and binding) for the nucleobase cation symporter 1 (NCS1) proteins, from the closely related C4 grasses Zea mays and Setaria viridis, differ from that of Arabidopsis thaliana and Chlamydomonas reinhardtii NCS1. Solute specificity profiles for NCS1 from Z. mays (ZmNCS1) and S. viridis (SvNCS1) were determined through heterologous complementation studies in NCS1-deficient Saccharomyces cerevisiae strains. The four Viridiplantae NCS1 proteins transport the purines adenine and guanine, but unlike the dicot and algal NCS1, grass NCS1 proteins fail to transport the pyrimidine uracil. Despite the high level of amino acid sequence similarity, ZmNCS1 and SvNCS1 display distinct solute transport and recognition profiles. SvNCS1 transports adenine, guanine, hypoxanthine, cytosine, and allantoin and competitively binds xanthine and uric acid. ZmNCS1 transports adenine, guanine, and cytosine and competitively binds, 5-fluorocytosine, hypoxanthine, xanthine, and uric acid. The differences in grass NCS1 profiles are due to a limited number of amino acid alterations. These amino acid residues do not correspond to amino acids essential for overall solute and cation binding or solute transport, as previously identified in bacterial and fungal NCS1, but rather may represent residues involved in subtle solute discrimination. The data presented here reveal that within Viridiplantae, NCS1 proteins transport a broad range of nucleobase compounds and that the solute specificity profile varies with species.
authors.affiliation: Department of Biology, Indiana University-Purdue University Fort Wayne, 2101 East Coliseum Blvd., Fort Wayne, IN, 46805, USA.
authors.forename: Micah
authors.initials: M
authors.lastname: Rapp
authors.affiliation: Department of Biology, Indiana University-Purdue University Fort Wayne, 2101 East Coliseum Blvd., Fort Wayne, IN, 46805, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Schein
authors.affiliation: Department of Biology, Indiana University-Purdue University Fort Wayne, 2101 East Coliseum Blvd., Fort Wayne, IN, 46805, USA.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Hunt
authors.affiliation: Department of Biology, Indiana University-Purdue University Fort Wayne, 2101 East Coliseum Blvd., Fort Wayne, IN, 46805, USA.
authors.forename: Vamsi
authors.initials: V
authors.lastname: Nalam
authors.affiliation: Department of Biology, Indiana University-Purdue University Fort Wayne, 2101 East Coliseum Blvd., Fort Wayne, IN, 46805, USA.
authors.forename: George S
authors.initials: GS
authors.lastname: Mourad
authors.affiliation: Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, 123 Huntington St, New Haven, CT, 06511, USA. neil.schultes@ct.gov.
authors.forename: Neil P
authors.initials: NP
authors.lastname: Schultes
mesh_terms: D000225:Adenine / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D017343:Genes, Plant; D005816:Genetic Complementation Test; D007700:Kinetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D012441:Saccharomyces cerevisiae; D032983:Setaria Plant / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
chemical_list: D027682:Cation Transport Proteins; D010940:Plant Proteins; D000225:Adenine
keywords: Nucleobase cation symporter 1; Purine; Pyrimidine; Setaria viridis; Zea mays