scholarly journals Functional Analysis of Three Sulfide:Quinone Oxidoreductase Homologs in Chlorobaculum tepidum

2008 ◽  
Vol 191 (3) ◽  
pp. 1026-1034 ◽  
Author(s):  
Leong-Keat Chan ◽  
Rachael M. Morgan-Kiss ◽  
Thomas E. Hanson
Keyword(s):  
Double Mutant ◽  
Sulfide Oxidation ◽  
Chlorobium Tepidum ◽  
Sulfur Source ◽  
Reduction Activity ◽  
Chlorobaculum Tepidum ◽  
Sulfide:Quinone Oxidoreductase ◽  
Genes Encoding ◽  
Green Sulfur ◽  
Phototrophic Growth

ABSTRACT Sulfide:quinone oxidoreductase (SQR) catalyzes sulfide oxidation during sulfide-dependent chemo- and phototrophic growth in bacteria. The green sulfur bacterium Chlorobaculum tepidum (formerly Chlorobium tepidum) can grow on sulfide as the sole electron donor and sulfur source. C. tepidum contains genes encoding three SQR homologs: CT0117, CT0876, and CT1087. This study examined which, if any, of the SQR homologs possess sulfide-dependent ubiquinone reduction activity and are required for growth on sulfide. In contrast to CT0117 and CT0876, transcripts of CT1087 were detected only when cells actively oxidized sulfide. Mutation of CT0117 or CT1087 in C. tepidum decreased SQR activity in membrane fractions, and the CT1087 mutant could not grow with ≥6 mM sulfide. Mutation of both CT0117 and CT1087 in C. tepidum completely abolished SQR activity, and the double mutant failed to grow with ≥4 mM sulfide. A C-terminal His6-tagged CT1087 protein was membrane localized, as was SQR activity. Epitope-tagged CT1087 was detected only when sulfide was actively consumed by cells. Recombinantly produced CT1087 and CT0117 proteins had SQR activity, while CT0876 did not. In summary, we conclude that, under the conditions tested, both CT0117 and CT1087 function as SQR proteins in C. tepidum. CT0876 may support the growth of C. tepidum at low sulfide concentrations, but no evidence was found for SQR activity associated with this protein.

scholarly journals Cupriavidus necator H16 Uses Flavocytochrome c Sulfide Dehydrogenase To Oxidize Self-Produced and Added Sulfide

2017 ◽  
Vol 83 (22) ◽  
Author(s):  
Chuanjuan Lü ◽  
Yongzhen Xia ◽  
Daixi Liu ◽  
Rui Zhao ◽  
Rui Gao ◽  
...  
Keyword(s):  
Gas Phase ◽  
Heterotrophic Bacteria ◽  
Sulfide Oxidation ◽  
Cupriavidus Necator ◽  
Content Type ◽  
Sulfide:Quinone Oxidoreductase ◽  
Transport Chain ◽  
Genes Encoding ◽  
Cupriavidus Necator H16 ◽  
Chemolithotrophic Bacteria

ABSTRACT Production of sulfide (H2S, HS−, and S2−) by heterotrophic bacteria during aerobic growth is a common phenomenon. Some bacteria with sulfide:quinone oxidoreductase (SQR) and persulfide dioxygenase (PDO) can oxidize self-produced sulfide to sulfite and thiosulfate, but other bacteria without these enzymes release sulfide into the medium, from which H2S can volatilize into the gas phase. Here, we report that Cupriavidus necator H16, with the fccA and fccB genes encoding flavocytochrome c sulfide dehydrogenases (FCSDs), also oxidized self-produced H2S. A mutant in which fccA and fccB were deleted accumulated and released H2S. When fccA and fccB were expressed in Pseudomonas aeruginosa strain Pa3K with deletions of its sqr and pdo genes, the recombinant rapidly oxidized sulfide to sulfane sulfur. When PDO was also cloned into the recombinant, the recombinant with both FCSD and PDO oxidized sulfide to sulfite and thiosulfate. Thus, the proposed pathway is similar to the pathway catalyzed by SQR and PDO, in which FCSD oxidizes sulfide to polysulfide, polysulfide spontaneously reacts with reduced glutathione (GSH) to produce glutathione persulfide (GSSH), and PDO oxidizes GSSH to sulfite, which chemically reacts with polysulfide to produce thiosulfate. About 20.6% of sequenced bacterial genomes contain SQR, and only 3.9% contain FCSD. This is not a surprise, since SQR is more efficient in conserving energy because it passes electrons from sulfide oxidation into the electron transport chain at the quinone level, while FCSD passes electrons to cytochrome c. The transport of electrons from the latter to O2 conserves less energy. FCSDs are grouped into three subgroups, well conserved at the taxonomic level. Thus, our data show the diversity in sulfide oxidation by heterotrophic bacteria. IMPORTANCE Heterotrophic bacteria with SQR and PDO can oxidize self-produced sulfide and do not release H2S into the gas phase. C. necator H16 has FCSD but not SQR, and it does not release H2S. We confirmed that the bacterium used FCSD for the oxidation of self-produced sulfide. The bacterium also oxidized added sulfide. The common presence of SQRs, FCSDs, and PDOs in heterotrophic bacteria suggests the significant role of heterotrophic bacteria in sulfide oxidation, participating in sulfur biogeochemical cycling. Further, FCSDs have been identified in anaerobic photosynthetic bacteria and chemolithotrophic bacteria, but their physiological roles are unknown. We showed that heterotrophic bacteria use FCSDs to oxidize self-produced sulfide and extraneous sulfide, and they may be used for H2S bioremediation.

scholarly journals Nine Mutants of Chlorobium tepidum Each Unable To Synthesize a Different Chlorosome Protein Still Assemble Functional Chlorosomes

2004 ◽  
Vol 186 (3) ◽  
pp. 646-653 ◽  
Author(s):  
Niels-Ulrik Frigaard ◽  
Hui Li ◽  
Kirstin J. Milks ◽  
Donald A. Bryant
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Protein Composition ◽  
Chlorobium Tepidum ◽  
Protein Species ◽  
Wild Type ◽  
Absorbance Maximum ◽  
Genes Encoding ◽  
Green Sulfur ◽  
Photosynthetic Antenna

ABSTRACT Chlorosomes of the green sulfur bacterium Chlorobium tepidum comprise mostly bacteriochlorophyll c (BChl c), small amounts of BChl a, carotenoids, and quinones surrounded by a lipid-protein envelope. These structures contain 10 different protein species (CsmA, CsmB, CsmC, CsmD, CsmE, CsmF, CsmH, CsmI, CsmJ, and CsmX) but contain relatively little total protein compared to other photosynthetic antenna complexes. Except for CsmA, which has been suggested to bind BChl a, the functions of the chlorosome proteins are not known. Nine mutants in which a single csm gene was inactivated were created; these mutants included genes encoding all chlorosome proteins except CsmA. All mutants had BChl c contents similar to that of the wild-type strain and had growth rates indistinguishable from or within ∼90% (CsmC− and CsmJ−) of those of the wild-type strain. Chlorosomes isolated from the mutants lacked only the protein whose gene had been inactivated and were generally similar to those from the wild-type strain with respect to size, shape, and BChl c, BChl a, and carotenoid contents. However, chlorosomes from the csmC mutant were about 25% shorter than those from the wild-type strain, and the BChl c absorbance maximum was blue-shifted about 8 nm, indicating that the structure of the BChl c aggregates in these chlorosomes is altered. The results of the present study establish that, except with CsmA, when the known chlorosome proteins are eliminated individually, none of them are essential for the biogenesis, light harvesting, or structural organization of BChl c and BChl a within the chlorosome. These results demonstrate that chlorosomes are remarkably robust structures that can tolerate considerable changes in protein composition.

Membrane proteome of the green sulfur bacterium Chlorobium tepidum (syn. Chlorobaculum tepidum) analyzed by gel-based and gel-free methods

2010 ◽  
Vol 104 (2-3) ◽  
pp. 153-162 ◽  
Author(s):  
Kalliopi Kouyianou ◽  
Michalis Aivaliotis ◽  
Kris Gevaert ◽  
Michael Karas ◽  
Georgios Tsiotis
Keyword(s):  
Chlorobium Tepidum ◽  
Green Sulfur Bacterium ◽  
Membrane Proteome ◽  
Chlorobaculum Tepidum ◽  
Green Sulfur

scholarly journals SoxAX Binding Protein, a Novel Component of the Thiosulfate-Oxidizing Multienzyme System in the Green Sulfur Bacterium Chlorobium tepidum

2008 ◽  
Vol 190 (18) ◽  
pp. 6097-6110 ◽  
Author(s):  
Takuro Ogawa ◽  
Toshinari Furusawa ◽  
Ryohei Nomura ◽  
Daisuke Seo ◽  
Naomi Hosoya-Matsuda ◽  
...  
Keyword(s):  
Binding Protein ◽  
Protein A ◽  
Total Activity ◽  
Chlorobium Tepidum ◽  
Hydrolytic Cleavage ◽  
Green Sulfur Bacterium ◽  
Reading Frame ◽  
Reduction Activity ◽  
Multienzyme System ◽  
Green Sulfur

ABSTRACT From the photosynthetic green sulfur bacterium Chlorobium tepidum (pro synon. Chlorobaculum tepidum), we have purified three factors indispensable for the thiosulfate-dependent reduction of the small, monoheme cytochrome c 554. These are homologues of sulfur-oxidizing (Sox) system factors found in various thiosulfate-oxidizing bacteria. The first factor is SoxYZ that serves as the acceptor for the reaction intermediates. The second factor is monomeric SoxB that is proposed to catalyze the hydrolytic cleavage of sulfate from the SoxYZ-bound oxidized product of thiosulfate. The third factor is the trimeric cytochrome c 551, composed of the monoheme cytochrome SoxA, the monoheme cytochrome SoxX, and the product of the hypothetical open reading frame CT1020. The last three components were expressed separately in Escherichia coli cells and purified to homogeneity. In the presence of the other two Sox factors, the recombinant SoxA and SoxX showed a low but discernible thiosulfate-dependent cytochrome c 554 reduction activity. The further addition of the recombinant CT1020 protein greatly increased the activity, and the total activity was as high as that of the native SoxAX-CT1020 protein complex. The recombinant CT1020 protein participated in the formation of a tight complex with SoxA and SoxX and will be referred to as SAXB (SoxAX binding protein). Homologues of the SAXB gene are found in many strains, comprising roughly about one-third of the thiosulfate-oxidizing bacteria whose sox gene cluster sequences have been deposited so far and ranging over the Chlorobiaciae, Chromatiaceae, Hydrogenophilaceae, Oceanospirillaceae, etc. Each of the deduced SoxA and SoxX proteins of these bacteria constitute groups that are distinct from those found in bacteria that apparently lack SAXB gene homologues.

scholarly journals Two Genes Encoding New Carotenoid-Modifying Enzymes in the Green Sulfur Bacterium Chlorobium tepidum

2006 ◽  
Vol 188 (17) ◽  
pp. 6217-6223 ◽  
Author(s):  
Julia A. Maresca ◽  
Donald A. Bryant
Keyword(s):  
Green Sulfur Bacteria ◽  
The Other ◽  
Chlorobium Tepidum ◽  
Green Sulfur Bacterium ◽  
Gene Encoding ◽  
Anoxygenic Phototrophs ◽  
Sulfur Bacteria ◽  
Genes Encoding ◽  
Green Sulfur ◽  
Predicted Function

ABSTRACT The green sulfur bacterium Chlorobium tepidum produces chlorobactene as its primary carotenoid. Small amounts of chlorobactene are hydroxylated by the enzyme CrtC and then glucosylated and acylated to produce chlorobactene glucoside laurate. The genes encoding the enzymes responsible for these modifications of chlorobactene, CT1987, and CT0967, have been identified by comparative genomics, and these genes were insertionally inactivated in C. tepidum to verify their predicted function. The gene encoding chlorobactene glucosyltransferase (CT1987) has been named cruC, and the gene encoding chlorobactene lauroyltransferase (CT0967) has been named cruD. Homologs of these genes are found in the genomes of all sequenced green sulfur bacteria and filamentous anoxygenic phototrophs as well as in the genomes of several nonphotosynthetic bacteria that produce similarly modified carotenoids. The other bacteria in which these genes are found are not closely related to green sulfur bacteria or to one another. This suggests that the ability to synthesize modified carotenoids has been a frequently transferred trait.

scholarly journals The Diversity of Sulfide Oxidation and Sulfate Reduction Genes Expressed by the Bacterial Communities of the Cariaco Basin, Venezuela

2016 ◽  
Vol 10 (1) ◽  
pp. 140-149 ◽  
Author(s):  
Maria J. Rodriguez-Mora ◽  
Virginia P. Edgcomb ◽  
Craig Taylor ◽  
Mary I. Scranton ◽  
Gordon T. Taylor ◽  
...  
Keyword(s):  
Sulfate Reduction ◽  
Bacterial Communities ◽  
Sulfide Oxidation ◽  
Cariaco Basin ◽  
Sulfite Reductase ◽  
Chlorobium Tepidum ◽  
Gene Sequences ◽  
Sulfide:Quinone Oxidoreductase ◽  
Methylomicrobium Alcaliphilum ◽  
Qualitative Expression

Qualitative expression of dissimilative sulfite reductase (dsrA), a key gene in sulfate reduction, and sulfide:quinone oxidoreductase (sqr), a key gene in sulfide oxidation was investigated. Neither of the two could be amplified from mRNA retrieved with Niskin bottles but were amplified from mRNA retrieved by the Deep SID. Thesqrandsqr-like genes retrieved from the Cariaco Basin were related to thesqrgenes from aBradyrhizobiumsp.,Methylomicrobium alcaliphilum,Sulfurovumsp. NBC37-1,Sulfurimonas autotrophica, Thiorhodospira sibiricaandChlorobium tepidum. ThedsrAgene sequences obtained from the redoxcline of the Cariaco Basin belonged to chemoorganotrophic and chemoautotrophic sulfate and sulfur reducers belonging to the class Deltaproteobacteria (phylum Proteobacteria) and the order Clostridiales (phylum Firmicutes).

scholarly journals Two exopolyphosphatases with distinct molecular architectures and substrate specificities from the thermophilic green-sulfur bacterium Chlorobium tepidum TLS

Microbiology ◽  
2014 ◽  
Vol 160 (9) ◽  
pp. 2067-2078 ◽  
Author(s):  
Tomás Albi ◽  
Aurelio Serrano
Keyword(s):  
Catalytic Efficiency ◽  
Medium Size ◽  
Chlorobium Tepidum ◽  
Green Sulfur Bacterium ◽  
Microbial World ◽  
Absolute Requirement ◽  
Genes Encoding ◽  
Marked Preference ◽  
Green Sulfur ◽  
Chain Lengths

The genome of the thermophilic green-sulfur bacterium Chlorobium tepidum TLS possesses two genes encoding putative exopolyphosphatases (PPX; EC 3.6.1.11), namely CT0099 (ppx1, 993 bp) and CT1713 (ppx2, 1557 bp). The predicted polypeptides of 330 and 518 aa residues are Ppx-GppA phosphatases of different domain architectures – the largest one has an extra C-terminal HD domain – which may represent ancient paralogues. Both ppx genes were cloned and overexpressed in Escherichia coli BL21(DE3). While CtPPX1 was validated as a monomeric enzyme, CtPPX2 was found to be a homodimer. Both PPX homologues were functional, K+-stimulated phosphohydrolases, with an absolute requirement for divalent metal cations and a marked preference for Mg2+. Nevertheless, they exhibited remarkably different catalytic specificities with regard to substrate classes and chain lengths. Even though both enzymes were able to hydrolyse the medium-size polyphosphate (polyP) P13–18 (polyP mix with mean chain length of 13–18 phosphate residues), CtPPX1 clearly reached its highest catalytic efficiency with tripolyphosphate and showed substantial nucleoside triphosphatase (NTPase) activity, while CtPPX2 preferred long-chain polyPs (>300 Pi residues) and did not show any detectable NTPase activity. These catalytic features, taken together with the distinct domain architectures and molecular phylogenies, indicate that the two PPX homologues of Chl. tepidum belong to different Ppx-GppA phosphatase subfamilies that should play specific biochemical roles in nucleotide and polyP metabolisms. In addition, these results provide an example of the remarkable functional plasticity of the Ppx-GppA phosphatases, a family of proteins with relatively simple structures that are widely distributed in the microbial world.

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