The hmc operon of Desulfovibrio vulgaris subsp. vulgaris Hildenborough encodes a potential transmembrane redox protein complex

Rossi, Mosè; Pollock, W. B. R.; Reij, M.W.; Keon, Richard G.; Fu, Rongdian; Voordouw, Gerrit

doi:10.1128/jb.175.15.4699-4711.1993

Cited by 140 publications

(112 citation statements)

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“…Thus, the spectroscopic and chemical data of D. gigas Hmc, and the sequence studies of the homologous protein from D. vulgaris taken together point to the presence of 14-15 bishistidinyl coordinated low-spin hemes and l-2 high-spin hemes in D. gigas Hmc. Rossi et al [9] have suggested that each of the Hmc domains interacts with one of the three hydrogenases found in D. vulgaris [24,25]. However, in the same paper, the authors present a scheme in which the [Fe]-hydrogenase of D. vulgaris is presented as the only hydrogenase reacting with Hmc, which is proposed to be part of a transmembrane electron transfer complex.…”

Section: Discussionmentioning

confidence: 88%

Isolation and characterization of a high molecular weight cytochrome from the sulfate reducing bacterium Desulfovibrio gigas

et al. 1994

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A high molecular weight c-type cytochrome (Hmc) was purified and characterized from Desulfovibrio gigas. The molecular weight was estimated to be 67 kDa by SDS-PAGE and its N-terminus is homologous to those of the 16 hemes containing high molecular weight cytochrome c from Desulfovibrio vulgaris strains Hildenborough and Miyaxaki. The purified hemoprotein shows c-type cytochrome absorption spectrum with s,,,(red) = 368 mM-' . cm-'. A band at 640 nm, characteristic of high-spin hemes, was detected The EPR spectra show the presence of two high-spin heme species, plus several non-equivalent low-spin hemes. The heme reduction potentials, at pH 7.6, range from -50 mV to -315 mV. In contrast to what has been described for D. vulgaris Hmc, the protein isolated from D. gigas directly accepts electrons from hydrogenase and further reduces other redox proteins.

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Section: Discussionmentioning

confidence: 88%

Isolation and characterization of a high molecular weight cytochrome from the sulfate reducing bacterium Desulfovibrio gigas

et al. 1994

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“…Alignments were made using the Pileup and Prettybox programmes (Daresbury). hynb, hynB gene product from D. gigas [28]; hyba, hybA gene product of E. coli hydrogenase 2 [11]; nrfc, nrfC gene product of the nitrite reductase operon of E. coli [29]; fdoh, H. influenzae fdoH gene product [30]. which it is thought to be located by a hydrophobic C-terminal region.…”

Section: Resultsmentioning

confidence: 99%

Reassignment of the gene encoding the Escherichia coli hydrogenase 2 small subunit

Sargent¹,

Ballantine²,

Rugman³

et al. 1998

European Journal of Biochemistry

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An active tryptic fragment of hydrogenase 2 from Escherichia coli has been isolated from the periplasmic face of the cytoplasmic membrane, and the large and small subunits N-terminally sequenced. The large subunit is encoded by the hybC gene and shows no N-terminal processing, other than removal of the initiator methionine during its biosynthesis. Both N-terminal and the subsequent internal trypticfragment amino acid sequence indicate that the small subunit is neither encoded by hybA, a gene previously identified as encoding the small subunit [Menon et al. (1994) J. Bacteriol. 176, 4416Ϫ4423], nor any of the remaining genes in the hyb operon. Genome sequence analysis revealed the presence of an open reading frame which could potentially encode the peptide sequences of the proteolysed small subunit. The gene, designated hyb0, lies directly upstream of, and is separated by two nucleotides from, the start of the hybA gene. Hyb0, which shares an approximate 40% identity with other hydrogenase small subunit amino acid sequences, is synthesised with an N-terminal signal sequence containing a twin-arginine motif which is probably required for export of the enzyme. In the mature enzyme the small subunit is proteolytically cleaved after Ala37. Immunological analysis of strains overproducing either recombinant Hyb0 or HybA using antibodies specific for hydrogenase 2, readily identified Hyb0 as the small subunit. In a pleiotropic hypB mutant, which is unable to insert nickel into the active site, both the large and small subunits accumulate as unprocessed, soluble forms, consistent with the two subunits being assembled and processed in a coordinated manner during biosynthesis.

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“…Hydrogenase activity and electron storage occur in the periplasm whereas sulfate reduction occurs in the cytoplasm, therefore, electrons must cross the cytoplasmic membrane. Before genome analysis, the Hmc complex (DVU0531-36, containing a hexadecaheme c-type cytochrome) represented the only known D. vulgaris transmembrane electron circuit [15][16][17] . However, genome analysis indicates the presence of four alternate transmembrane electron conduits ( Fig.…”

Section: Energy Metabolismmentioning

confidence: 99%

The genome sequence of the anaerobic, sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough

Heidelberg¹,

Seshadri²,

et al. 2004

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Sulfate-reducing bacteria (SRB) are anaerobic prokaryotes found ubiquitously in nature. SRB were the first nonphotosynthetic, anaerobic bacteria shown to generate energy (ATP) through electron transfer-coupled phosphorylation. For this process, the SRB typically use sulfate as the terminal electron acceptor for respiration of hydrogen or various organic acids, which results in the production of sulfide, a highly reactive and toxic end-product. Beyond their obvious function in the sulfur cycle, SRB play an important role in global cycling of numerous other elements 1 . For example, in the carbon cycle, the SRB form part of microbial consortia that completely mineralize organic carbon in anaerobic environments; polymeric materials (e.g., cellulose) are first depolymerized and metabolized by fermentative microorganisms, and the resulting organic acid and reduced gas (that is, CO and H 2 ) end-products are further fermented or oxidized by other microbes, including SRB. The latter are particularly active in sulfate-rich (e.g., marine) environments, where they effectively link the global sulfur and carbon cycles 1,2 .Beyond these ecological roles, SRB also have a major economic impact because of their involvement in biocorrosion of ferrous metals in anaerobic environments 3 , described as "industrial venereal disease-it's expensive, everybody has it, and nobody wants to talk about it" 4 . For example, because SRB are abundant in oil fields, their metabolism has many negative consequences for the petroleum industry (e.g., corrosion of drilling and pumping machinery and storage tanks, souring of oil by sulfide production, plugging of machinery and rock pores with biomass and sulfide precipitates). The SRB also contribute to bioremediation of toxic metal ions 5,6 . Their metabolism increases the pH, causing toxic metal ions like copper (II), nickel (II) and cadmium (II) to precipitate as metal sulfides in acidic aquatic environments (e.g., mine effluents). Additionally, SRB can deliver electrons directly to oxidized toxic metal ions, including uranium (VI), technetium (VII), and chromium (VI), converting these into less soluble, reduced forms. Hence, SRB-mediated reduction represents a potentially useful mechanism for the bioremediation of metal ion contaminants from anaerobic sediments 6 .Most research on the metabolism and biochemistry of SRB has been done on the genus Desulfovibrio, a member of the δ-proteobacteria The genome sequence of the anaerobic, sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough Desulfovibrio vulgaris Hildenborough is a model organism for studying the energy metabolism of sulfate-reducing bacteria (SRB) and for understanding the economic impacts of SRB, including biocorrosion of metal infrastructure and bioremediation of toxic metal ions. The 3,570,858 base pair (bp) genome sequence reveals a network of novel c-type cytochromes, connecting multiple periplasmic hydrogenases and formate dehydrogenases, as a key feature of its energy metabolism. The relative arrangement of genes encod...

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The hmc operon of Desulfovibrio vulgaris subsp. vulgaris Hildenborough encodes a potential transmembrane redox protein complex

Cited by 140 publications

References 46 publications

Isolation and characterization of a high molecular weight cytochrome from the sulfate reducing bacterium Desulfovibrio gigas

Isolation and characterization of a high molecular weight cytochrome from the sulfate reducing bacterium Desulfovibrio gigas

Reassignment of the gene encoding the Escherichia coli hydrogenase 2 small subunit

The genome sequence of the anaerobic, sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough

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