title: Characterization of the gene cluster involved in allantoate catabolism and its transcriptional regulation by the RpiR-type repressor HpxU in Klebsiella pneumoniae.
abstract: Bacteria, fungi, and plants have metabolic pathways for the utilization of nitrogen present in purine bases. In Klebsiella pneumoniae, the genes responsible for the assimilation of purine ring nitrogen are distributed in three separated clusters. We characterized the gene cluster involved in the metabolism of allantoate (genes KPN_01761 to KPN_01771). The functional assignments of HpxK, as an allantoate amidohydrolase, and of HpxU, as a regulator involved in the control of allantoate metabolism, were assessed experimentally. Gene hpxU encodes a repressor of the RpiR family that mediates the regulation of this system by allantoate. In this study, the binding of HpxU to the hpxF promoter and to the hpxU-hpxW intergenic region containing the divergent promoter for these genes was evidenced by electrophoretic mobility shift assays. Allantoate released the HpxU repressor from its target operators whereas other purine intermediate metabolites, such as allantoin and oxamate, failed to induce complex dissociation. Sequence alignment of the four HpxU identified operators identified TGAA-N8-TTCA as the consensus motif recognized by the HpxU repressor.
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Karla
authors.initials: K
authors.lastname: Guzmán
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Evangelina
authors.initials: E
authors.lastname: Campos
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Aguilera
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Lorena
authors.initials: L
authors.lastname: Toloza
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Giménez
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Aguilar
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Baldoma
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Josefa
authors.initials: J
authors.lastname: Badia
mesh_terms: D000481:Allantoin / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D000481:Allantoin