title: A membrane-bound nitrate reductase encoded by the narGHJI operon is responsible for anaerobic respiration in Halomonas maura.
abstract: The halophilic bacterium Halomonas maura is capable of anaerobic respiration on nitrates. By insertional mutagenesis with the minitransposon Tn-5 we obtained the mutant Tc62, which was incapable of anaerobic respiration on nitrates. An analysis of the regions adjacent to the transposon allowed us to characterize the membrane-bound anaerobic-respiratory nitrate reductase narGHJI gene cluster in H. maura. We identified consensus sequences for fumarate and nitrate reductase regulator (FNR)-like protein-binding sites in the promoter regions of the nar genes and consensus sequences corresponding to the NarL binding sites upstream of the nar genes. RT-PCR analysis showed that the narGHJI operon was expressed in response to anaerobic conditions when nitrate was available as electron acceptor. This membrane-bound nitrate reductase is the only enzyme responsible for anaerobic respiration on nitrate in H. maura. In this article we discuss the possible relationship between this enzyme and a dissimilatory nitrate-reduction-to-ammonia process (DNRA) in H. maura and its role in the colonization of the rhizosphere.
authors.affiliation: Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja s/n, 18071 Granada, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Argandoña
authors.forename: Fernando
authors.initials: F
authors.lastname: Martínez-Checa
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Llamas
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Arco
authors.forename: Emilia
authors.initials: E
authors.lastname: Quesada
authors.forename: Ana
authors.initials: A
authors.lastname: del Moral
mesh_terms: D000693:Anaerobiosis; D001483:Base Sequence; D002874:Chromosome Mapping; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D020632:Halomonas / Q000201:enzymology* / Q000235:genetics*; D008566:Membranes / Q000201:enzymology; D008969:Molecular Sequence Data; D050901:Nitrate Reductase / Q000235:genetics* / Q000378:metabolism*; D009876:Operon; D010957:Plasmids / Q000235:genetics
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D050901:Nitrate Reductase