Characterization of the gene cluster involved in allantoate catabolism and its transcriptional regulation by the RpiR-type repressor HpxU in Klebsiella pneumoniae

Autores/as

  • Karla Guzmán Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
  • Evangelina Campos Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
  • Laura Aguilera Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
  • Lorena Toloza Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
  • Rosa Giménez Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
  • Juan Aguilar Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
  • Laura Baldoma Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
  • Josefa Badia Department of Biochemistry and Molecular Biology, Institute of Biomedicine, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain

Palabras clave:

Klebsiella pneumoniae, allantoate metabolism, allantoate amidohydrolase, purine catabolism, RpiR-type repressor

Resumen

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 identifi ed operators identifi ed TGAA-N8-TTCA as the consensus motif recognized by the HpxU repressor. [Int Microbiol 2013; 16(3):XXX-XXX]

Keywords: Klebsiella pneumoniae · allantoate metabolism · allantoate amidohydrolase · purine catabolism · RpiR-type repressor

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