title: Synthesis of nickel-iron hydrogenase in Cupriavidus metallidurans is controlled by metal-dependent silencing and un-silencing of genomic islands.
abstract: Cupriavidus metallidurans CH34 is able to grow autotrophically as a hydrogen-oxidizing bacterium and produces nickel-dependent hydrogenases, even under heterotrophic conditions. Loss of its two native plasmids resulted in inability of the resulting strain AE104 to synthesize the hydrogenases and to grow autotrophically in phosphate-poor, Tris-buffered mineral salts medium (TMM). Three of eleven previously identified catabolic genomic islands (CMGIs; Van Houdt et al., 2009), two of which harbor the genes for the membrane-bound (CMGI-2) and the soluble hydrogenase (CMGI-3), were silenced in strain AE104 when cultivated in phosphate-poor TMM, explaining its inability to produce hydrogenases. Production of the soluble hydrogenase from the aut region 1 of CMGI-3, and concomitant autotrophic growth, was recovered when the gene for the zinc importer ZupT was deleted in strain AE104. The transcriptome of the ΔzupT mutant exhibited two up-regulated gene regions compared to its parent strain AE104. Expression of the genes in the aut region 1 increased independently of the presence of added zinc. A second gene region was expressed only under metal starvation conditions. This region encoded a TonB-dependent outer membrane protein, a putative metal chaperone plus paralogs of essential zinc-dependent proteins, indicating the presence of a zinc allocation pathway in C. metallidurans. Thus, expression of the genes for the soluble hydrogenase and the Calvin cycle enzymes on aut region 1 of CMGI-3 of C. metallidurans is under global control and needs efficient ZupT-dependent zinc allocation for a regulatory role, which might be discrimination of nickel.
authors.affiliation: Molecular Microbiology, Institute for Biology/Microbiology, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle/Saale, Germany. d.nies@mikrobiologie.uni-halle.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Herzberg
authors.forename: Marcel
authors.initials: M
authors.lastname: Schüttau
authors.forename: Matthias
authors.initials: M
authors.lastname: Reimers
authors.forename: Cornelia
authors.initials: C
authors.lastname: Große
authors.lastname: Hans-Günther-Schlegel
authors.forename: Dietrich H
authors.initials: DH
authors.lastname: Nies
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D049921:Cupriavidus / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D020868:Gene Silencing; D017930:Genes, Reporter; D044404:Genomic Islands; D006859:Hydrogen / Q000737:chemistry; D006864:Hydrogenase / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D005810:Multigene Family; D009154:Mutation; D009532:Nickel / Q000737:chemistry; D020411:Oligonucleotide Array Sequence Analysis; D010100:Oxygen / Q000737:chemistry; D020543:Proteome; D012313:RNA / Q000737:chemistry; D013997:Time Factors; D059467:Transcriptome; D015032:Zinc / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D008670:Metals; D020543:Proteome; D012313:RNA; D009532:Nickel; D006859:Hydrogen; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D015032:Zinc; D010100:Oxygen