title: Novel stand-alone RAM domain protein-mediated catalytic control of anthranilate phosphoribosyltransferase in tryptophan biosynthesis in Thermus thermophilus.
abstract: Regulation of amino acid metabolism (RAM) domains are widely distributed among prokaryotes. In most cases, a RAM domain fuses with a DNA-binding domain to act as a transcriptional regulator. The extremely thermophilic bacterium, Thermus thermophilus, only carries a single gene encoding a RAM domain-containing protein on its genome. This protein is a stand-alone RAM domain protein (SraA) lacking a DNA-binding domain. Therefore, we hypothesized that SraA, which senses amino acids through its RAM domain, may interact with other proteins to modify its functions. In the present study, we identified anthranilate phosphoribosyltransferase (AnPRT), the second enzyme in the tryptophan biosynthetic pathway, as a partner protein that interacted with SraA in T. thermophilus. In the presence of tryptophan, SraA was assembled to a decamer and exhibited the ability to form a stable hetero-complex with AnPRT. An enzyme assay revealed that AnPRT was only inhibited by tryptophan in the presence of SraA. This result suggests a novel feedback control mechanism for tryptophan biosynthesis through an inter-RAM domain interaction in bacteria.
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kubota
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Matsushita
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Tomita
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Kosono
authors.affiliation: RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Kuzuyama
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan. umanis@mail.ecc.u-tokyo.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Nishiyama
mesh_terms: D000877:Anthranilate Phosphoribosyltransferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D025461:Feedback, Physiological; D011485:Protein Binding; D055503:Protein Multimerization; D016963:Thermus thermophilus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D014364:Tryptophan / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D014364:Tryptophan; D000877:Anthranilate Phosphoribosyltransferase
keywords: Anthranilate phosphoribosyltransferase; Feedback inhibition; RAM domain; Thermus thermophilus; Tryptophan biosynthesis