Analysis of the plastidic phosphate translocator gene family in Arabidopsis and identification of new phosphate translocator-homologous transporters, classified by their putative substrate-binding site.
Analysis of the Arabidopsis genome revealed the complete set of plastidic phosphate translocator (pPT) genes. The Arabidopsis genome contains 16 pPT genes: single copies of genes coding for the triose phosphate/phosphate translocator and the xylulose phosphate/phosphate translocator, and two genes coding for each the phosphoenolpyruvate/phosphate translocator and the glucose-6-phosphate/phosphate translocator. A relatively high number of truncated phosphoenolpyruvate/phosphate translocator genes (six) and glucose-6-phosphate/phosphate translocator genes (four) could be detected with almost conserved intron/exon structures as compared with the functional genes. In addition, a variety of PT-homologous (PTh) genes could be identified in Arabidopsis and other organisms. They all belong to the drug/metabolite transporter superfamily showing significant similarities to nucleotide sugar transporters (NSTs). The pPT, PTh, and NST proteins all possess six to eight transmembrane helices. According to the analysis of conserved motifs in these proteins, the PTh proteins can be divided into (a) the lysine (Lys)/arginine group comprising only non-plant proteins, (b) the Lys-valine/alanine/glycine group of Arabidopsis proteins, (c) the Lys/asparagine group of Arabidopsis proteins, and (d) the Lys/threonine group of plant and non-plant proteins. None of these proteins have been characterized so far. The analysis of the putative substrate-binding sites of the pPT, PTh, and NST proteins led to the suggestion that all these proteins share common substrate-binding sites on either side of the membrane each of which contain a conserved Lys residue.
Knappe
Silke
S
Botanisches Institut der Universität zu Köln, Lehrstuhl II, Gyrhofstrasse 15, D-50931 Cologne, Germany.
Flügge
Ulf-Ingo
UI
Fischer
Karsten
K
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D001665:Binding Sites; D001692:Biological Transport; D060365:Chloroplast Proteins; D002736:Chloroplasts / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D019298:Glucose-6-Phosphate / Q000235:genetics / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D033704:Nucleotide Transport Proteins / Q000235:genetics / Q000378:metabolism; D010428:Pentosephosphates / Q000235:genetics / Q000378:metabolism; D028061:Phosphate Transport Proteins / Q000235:genetics* / Q000378:metabolism; D010728:Phosphoenolpyruvate / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D060365:Chloroplast Proteins; D026901:Membrane Transport Proteins; D033704:Nucleotide Transport Proteins; D010428:Pentosephosphates; D028061:Phosphate Transport Proteins; D010940:Plant Proteins; C036130:xylulose 1,5-bisphosphate; D019298:Glucose-6-Phosphate; D010728:Phosphoenolpyruvate; D008239:Lysine