title: Molecular cloning and characterization of ATP-phosphoribosyl transferase from Arabidopsis, a key enzyme in the histidine biosynthetic pathway.
abstract: We have characterized two isoforms of ATP-phosphoribosyl transferase (ATP-PRT) from Arabidopsis (AtATP-PRT1 [accession no. AB025251] and AtATP-PRT2), catalyzing the first step of the pathway of hisidine (His) biosynthesis. The primary structures deduced from AtATP-PRT1 and AtATP-PRT2 cDNAs share an overall amino acid identity of 74.6% and contain N-terminal chloroplast transit peptide sequences. DNA-blot analyses indicated that the ATP-PRTs in Arabidopsis are encoded by two separate genes with a closely similar gene structural organization. Both gene transcripts were detected throughout development, and protein-blot analysis revealed predominant accumulation of the AtATP-PRT proteins in Arabidopsis leaves. The His auxotrophy of a his1 mutant of Saccharomyces cerevisiae was suppressed by the transformation with AtATP-PRT1 and AtATP-PRT2 cDNAs, indicating that both isoforms are functionally active ATP-PRT enzymes. The K(m) values for ATP and phosphoribosyl pyrophosphate of the recombinant AtATP-PRT proteins were comparable to those of the native ATP-PRTs from higher plants and bacteria. It was demonstrated that the recombinant AtATP-PRTs were inhibited by L-His (50% inhibition of initial activity = 40-320 microM), suggesting that His biosynthesis was regulated in plants through feedback inhibition by L-His.
authors.affiliation: International Research Laboratories, Ciba-Geigy (Japan) Ltd., 10-66 Miyuki-cho, Takarazuka 665-8666, Japan. ohtad@plant.osakafu-u.ac.jp
authors.forename: D
authors.initials: D
authors.lastname: Ohta
authors.forename: K
authors.initials: K
authors.lastname: Fujimori
authors.forename: M
authors.initials: M
authors.lastname: Mizutani
authors.forename: Y
authors.initials: Y
authors.lastname: Nakayama
authors.forename: R
authors.initials: R
authors.lastname: Kunpaisal-Hashimoto
authors.forename: S
authors.initials: S
authors.lastname: Münzer
authors.forename: A
authors.initials: A
authors.lastname: Kozaki
mesh_terms: D001276:ATP Phosphoribosyltransferase / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D018744:DNA, Plant / Q000235:genetics / Q000302:isolation & purification; D017343:Genes, Plant; D006639:Histidine / Q000096:biosynthesis; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D018744:DNA, Plant; D007527:Isoenzymes; D012333:RNA, Messenger; D018749:RNA, Plant; D006639:Histidine; D001276:ATP Phosphoribosyltransferase