title: Linkage between toxin production and purine biosynthesis in Clostridium difficile.
abstract: The production of toxins A and B by Clostridium difficile was greatly enhanced under biotin-limited conditions, in which a 140-kDa protein was expressed strongly. Gene cloning revealed that this protein was a homologue of formylglycinamidine ribonucleotide synthetase (FGAM synthetase, EC 6.3.5.3), which is known as PurL in Escherichia coli and catalyses the fourth step of the de novo purine biosynthesis pathway. This enzyme consisted of a single polypeptide, although FGAM synthetases of gram-positive bacteria usually consist of two subunits. Inhibition of the enzymic activity of C. difficile PurL by O-diazoacetyl-L-serine (azaserine) resulted in enhanced toxin B production even in biotin-sufficient conditions. In contrast, blockade of the preceding step of the PurL catalysing step by sulfamethoxazole inhibited toxin B production almost completely. These results suggest that accumulation of formylglycinamide ribonucleotide (FGAR), a substrate of FGAM synthetase, enhances toxin production by C difficile and depletion of FGAR reduces toxin production.
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Maegawa
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Karasawa
authors.affiliation: Department of Bacteriology, School of Medicine, Kanazawa University, Kanazawa 920-8640, *College of Medical Technology and Nursing and †Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba 305, Japan.
authors.forename: Toshiko
authors.initials: T
authors.lastname: Ohta
authors.forename: Xingmin
authors.initials: X
authors.lastname: Wang
authors.forename: Haru
authors.initials: H
authors.lastname: Kato
authors.affiliation: Department of Bacteriology, School of Medicine, Kanazawa University, Kanazawa 920-8640, *College of Medical Technology and Nursing and †Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba 305, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Hayashi
authors.forename: Shinichi
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001377:Azaserine / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D001427:Bacterial Toxins / Q000096:biosynthesis*; D001710:Biotin / Q000378:metabolism*; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016360:Clostridioides difficile / Q000187:drug effects / Q000378:metabolism*; D003603:Cytotoxins / Q000096:biosynthesis; D004768:Enterotoxins / Q000096:biosynthesis*; D029968:Escherichia coli Proteins; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008025:Ligases; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011687:Purines / Q000096:biosynthesis*; D012265:Ribonucleotides / Q000737:chemistry / Q000378:metabolism; D017385:Sequence Homology; D013420:Sulfamethoxazole / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D011687:Purines; D012265:Ribonucleotides; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile; C002824:phosphoribosyl-N-formylglycineamide; D001710:Biotin; D001377:Azaserine; D008025:Ligases; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; C102675:PurL protein, E coli; C022385:phosphoribosylformylglycinamidine synthetase; D013420:Sulfamethoxazole; D005998:Glycine; C030985:purine