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A J Biel - One of the best experts on this subject based on the ideXlab platform.

  • Nucleotide sequence of the Rhodobacter Capsulatus hemH gene
    Gene, 1996
    Co-Authors: Ekaterina Kanazireva, A J Biel
    Abstract:

    Abstract The last step in heme synthesis is the insertion of iron into the ring of protoporphyrin IX. The enzyme which catalyzes this reaction, ferrochelatase (FC), is encoded by the hemH gene. A clone containing this gene from Rhodobacter Capsulatus, a purple non-sulfur photosynthetic bacterium, has been sequenced. A single open reading frame was found which could encode a protein of 351 amino acids. This putative protein is very similar to other FC and contains the FC signature sequence

  • Cloning and overexpression of the Rhodobacter Capsulatus hemH gene.
    Journal of Bacteriology, 1995
    Co-Authors: Ekaterina Kanazireva, A J Biel
    Abstract:

    In photosynthetically grown Rhodobacter Capsulatus, heme is a qualitatively minor end product of the common tetrapyrrole pathway, but it may play a significant regulatory role. Heme is synthesized from protoporphyrin by the product of the hemH gene, ferrochelatase. We have cloned the R. Capsulatus hemH gene by complementation of an Escherichia coli hemH mutant. When a plasmid carrying the hemH gene is returned to R. Capsulatus, ferrochelatase activity increases, aminolevulinate synthase activity decreases, and bacteriochlorophyll levels are dramatically lowered. This is the first in vivo evidence to suggest that heme feedback inhibits aminolevulinate synthase in R. Capsulatus, thereby reducing porphyrin synthesis.

  • Oxygen-regulated steps in the Rhodobacter Capsulatus tetrapyrrole biosynthetic pathway.
    Journal of Bacteriology, 1992
    Co-Authors: A J Biel
    Abstract:

    The effect of exogenous aminolevulinate and porphobilinogen on protoporphyrin accumulation in Rhodobacter Capsulatus was measured. Oxygen inhibited protoporphyrin accumulation in strain AJB456, a bchH mutant, even in the presence of exogenous aminolevulinate, suggesting that some step in the formation of protoporphyrin from aminolevulinate is regulated by oxygen. In contrast, in the presence of exogenous porphobilinogen, oxygen did not inhibit protoporphyrin accumulation. The results presented in this study indicate that oxygen regulates the formation of porphobilinogen from aminolevulinate.

  • Characterization of a coproporphyrin-protein complex from Rhodobacter Capsulatus.
    Fems Microbiology Letters, 1991
    Co-Authors: A J Biel
    Abstract:

    Abstract Rhodobacter Capsulatus strain AJB530 excretes large amounts of coproporphyrin into the culture supernatant. The coproporphyrin was precipitable with ammonium sulfate, suggesting that it was part of a macromolecular complex. Analysis of an ammonium sulfate fraction indicated that the coproporphyrin was bound to a 66-kDa protein with a p I ′ of 4.0. The same protein was found in the culture supernatant of the bch + strain PAS100.

  • Use of a lacZ fusion to study transcriptional regulation of the Rhodobacter Capsulatus hemA gene.
    FEMS microbiology letters, 1991
    Co-Authors: Maureen S. Wright, Susan W. Biel, J J Eckert, A J Biel
    Abstract:

    An EcoRI fragment containing the Rhodobacter Capsulatus hemA promoter has been cloned into a lacZ translational fusion vector. The resulting plasmid produced a hemA-lacZ fusion protein with a molecular mass of 147,000. Expression of the hemA-lacZ fusion, as measured by production of beta-galactosidase, was regulated 2- to 3-fold by oxygen tension. The unexpectedly small change in beta-galactosidase levels suggests that transcriptional regulation of the hemA gene is not the major factor in oxygen-mediated control of porphyrin synthesis.

Gabriele Klug - One of the best experts on this subject based on the ideXlab platform.

Robert Haselkorn - One of the best experts on this subject based on the ideXlab platform.

  • The Rhodobacter Capsulatus genome
    Photosynthesis Research, 2020
    Co-Authors: Robert Haselkorn, Alla Lapidus, Yakov Kogan, Čestmír Vlček, Jan Pačes, Václav Pačes, Pavel Ulbrich, Tamara Pečenková, Denis Rebrekov, Arthur J. Milgram
    Abstract:

    The genome of Rhodobacter Capsulatus has been completely sequenced. It consists of a single chromosome containing 3.5 Mb and a circular plasmid of 134 kb. This effort, started in 1992, began with a fine-structure restriction map of an overlapping set of cosmids that covered the genome. Cosmid sequencing led to a gapped genome that was filled by primer walking on the chromosome and by using lambda clones. Methods had to be developed to handle strong stops in the high GC (68%) inserts. Annotation was done with the ERGO system at Integrated Genomics, as was the reconstruction of the cell's metabolism. It was possible to recognize 3709 orfs of which functional assignments could be made with high confidence to 2392 (65%). Unusual features include the presence of numerous cryptic phage genomes embedded in the chromosome.

  • complete genome sequence of the photosynthetic purple nonsulfur bacterium Rhodobacter Capsulatus sb 1003
    Journal of Bacteriology, 2010
    Co-Authors: Hynek Strnad, Alla Lapidus, Jan Pačes, Václav Pačes, Pavel Ulbrich, Cestmir Vlcek, Robert Haselkorn
    Abstract:

    Rhodobacter Capsulatus SB 1003 belongs to the group of purple nonsulfur bacteria. Its genome consists of a 3.7-Mb chromosome and a 133-kb plasmid. The genome encodes genes for photosynthesis, nitrogen fixation, utilization of xenobiotic organic substrates, and synthesis of polyhydroxyalkanoates. These features made it a favorite research tool for studying these processes. Here we report its complete genome sequence.

  • The Rhodobacter Capsulatus Genome Project
    The Phototrophic Prokaryotes, 1999
    Co-Authors: Robert Haselkorn, Yakov Kogan, Jan Pačes, Václav Pačes, Arthur J. Milgram, Michael Fonstein, Vivek Kumar, Natalia Maltsev, Čestmír Vlček
    Abstract:

    Rhodobacter Capsulatus is a widely studied non-sulfur purple bacterium, particularly in the areas of photosynthesis, nitrogen fixation, transport, and utilization of organic substrates. The attraction of R. Capsulatusis based largely on its convenient system of genetic analysis, the Gene Transfer Agent [1]. With the GTA it is possible to construct deletions of any size with high efficiency. Therefore, it is possible to envision a complete functional analysis of the genome of this bacterium. For that analysis, we need first to determine the entire DNA sequence. With that information as a starting point, we can then prepare chips to study gene expression in the wild type under different conditions and in mutants missing individual regulatory genes. Based on the sequence, the GTA can be used to construct deletions frame by frame or cosmid by cosmid, allowing functions to be assigned to genes or groups of genes. Here, we present a progress report on each of these areas of genome analysis.

  • Rhodobacter Capsulatus SB1003
    Bacterial Genomes, 1998
    Co-Authors: Michael Fonstein, Elizabeth G. Koshy, Vivek Kumar, Paul Mourachov, Tatiana Nikolskaya, Michael Tsifansky, Su Zheng, Robert Haselkorn
    Abstract:

    DNA fragments from a Sau3a partial digest of Rhodobacter Capsulatus chromosomal DNA were size selected and cloned in the BamRI site of Lorist 6 by cosmid arm cloning and clones were individually transferred to eighteen 96-well plates (see also Chapter 28). Using a specially constructed printing device, individual cosmid clones were replicated onto nylon filters as ordered sets (18X coverage). These sets of clones were hybridized with individual XbaI and AseI fragments prepared from PFGE gels. Forty-one restriction sites for AseI and XbaI were mapped onto the 3.7-Mb genome by standard analyses of PFGE blot-hybridization data and of linking cosmids, revealed as clones hybridizing with two restriction fragments at once (Fonstein et al., 1992). Other types of hybridization (fragments to fragments, fragments to cosmid sets and riboprobes generated from the ends of the cosmids to cosmid sets) made it possible to vary the probe/target ratio in the hybridizations, thus distinguishing mapping artifacts connected with different repeated DNA sequences. At this stage, the cosmid clones were grouped in about 80 subcontigs, corresponding to the macro-restriction fragments from the PFG and the regions surrounding these rare sites. They formed two groups, one corresponding to the chromosome of R. Capsulatus, the other to its 134-kb plasmid.

Carl E. Bauer - One of the best experts on this subject based on the ideXlab platform.

  • Regulation of Photosystem Synthesis in Rhodobacter Capsulatus.
    Photosynthesis Research, 2020
    Co-Authors: Carl E. Bauer
    Abstract:

    Control of the synthesis of the purple bacterial photosystem has been an active area of research for many decades. The period of the 1960s involved physiological characterization of photosystem synthesis under different growth conditions. In the 1970s Barry Marrs and coworkers developed genetic tools that were used to define and map genes needed for synthesis of photopigments. The 1980s was a period of cloning and physical mapping of photosynthesis genes onto the chromosome, the demonstration that regulation of photosystem synthesis involved transcriptional control of gene expression, and sequence analysis of photosynthesis genes. The 1990s was a period of the discovery and characterization of regulatory genes that control synthesis of the photosystem in response to alterations in oxygen tension and light intensity. Although several photosynthetic organisms are mentioned for comparison and contrast, the focus of this minireview is on Rhodobacter Capsulatus.

  • Null Mutation of HvrA Compensates for Loss of an Essential relA/spoT-Like Gene in Rhodobacter Capsulatus
    Journal of Bacteriology, 2003
    Co-Authors: Shinji Masuda, Carl E. Bauer
    Abstract:

    We report that a single relA/spoT-like gene exists on the Rhodobacter Capsulatus chromosome, and its mutational loss is lethal. This gene could be mutated only under a mutational background of a null mutation in the nucleoid protein HvrA. This result suggests that there may be a direct link between HvrA-regulated promoters and the ppGpp-related stringent response.

  • the regb rega two component regulatory system controls synthesis of photosynthesis and respiratory electron transfer components in Rhodobacter Capsulatus
    Journal of Molecular Biology, 2001
    Co-Authors: Lee R Swem, Fevzi Daldal, Sylvie Elsen, Terry H Bird, Danielle L Swem, Hansgeorg Koch, Hannu Myllykallio, Carl E. Bauer
    Abstract:

    Recently, we demonstrated that the RegB/RegA two-component regulatory system from Rhodobacter Capsulatus functions as a global regulator of metabolic processes that either generate or consume reducing equivalents. For example, the RegB/RegA system controls expression of such energy generating processes as photosynthesis and hydrogen utilization. In addition, RegB/RegA also control nitrogen and carbon fixation pathways that utilize reducing equivalents. Here, we use a combination of DNase I protection and plasmid-based reporter expression studies to demonstrate that RegA directly controls synthesis of cytochrome cbb3 and ubiquinol oxidases that function as terminal electron acceptors in a branched respiratory chain. We also demonstrate that RegA controls expression of cytochromes c2, cy, and the cytochrome bc1 complex that are involved in both photosynthetic and respiratory electron transfer events. These data provide evidence that the RegB/RegA two-component system has a major role in controlling the synthesis of numerous processes that affect reducing equivalents in Rhodobacter Capsulatus.

  • Expression of Rat Liver Adohcy Hydrolase in a Rhodobacter Capsulatus ahcY Mutant Restores Pigment Formation and Photosynthetic Growth
    Biochemical and Biophysical Research Communications, 1995
    Co-Authors: R.r. Aksamit, J.j. Buggy, Carl E. Bauer
    Abstract:

    Abstract An amino acid alignment of fourteen S-adenosylhomocysteine hydrolases shows that sequences from six photosynthetic species and one species possibly derived from algae have an internal 36 to 41 amino acid sequence that is not present in hydrolase sequences from seven nonphotosynthetic species. In the photosynthetic eubacterium Rhodobacter Capsulatus , the StLB1 strain has a disrupted hydrolase gene, and hydrolase activity is not detectable. Photopigment synthesis and photosynthetic growth are significantly reduced in the StLB1 strain. Introduction of rat hydrolase cDNA into the StLB1 strain restored hydrolase activity, photopigment synthesis and photosynthetic growth. The results show that the 36 amino acid sequence of Rhodobacter Capsulatus S-adenosylhomocysteine hydrolase does not have a photosynthesis specific function.

  • Control of photosystem genes in Rhodobacter Capsulatus
    Trends in Genetics, 1993
    Co-Authors: Carl E. Bauer, Joseph J. Buggy, Chere S. Mosley
    Abstract:

    Abstract Two environmental factors, oxygen and high light intensity, are known to repress synthesis of the Rhodobacter Capsulatus photosystem. One level of regulation is the control of light harvesting and reaction centre gene expression at the point of transcription initiation. This has recently been shown to involve transcriptional activators which exhibit sequence similarity to members of the ‘two-component' class of prokaryotic regulators. An additional level of regulation involves the formation of ‘superoperons' that transcriptionally link pigment biosynthesis operons with operons that code for the light harvesting and reaction centre structural genes. A final level of regulation involves the selective degradation of reaction centre mRNA transcripts which influence the stoichiometric synthesis of the light harvesting and reaction centre complexes.

Alastair G. Mcewan - One of the best experts on this subject based on the ideXlab platform.

  • Molybdate-dependent expression of dimethylsulfoxide reductase in Rhodobacter Capsulatus
    Fems Microbiology Letters, 2000
    Co-Authors: Peter S. Solomon, Anthony L. Shaw, Graeme R. Hanson, Silke Leimkuhler, Michael D. Young, Werner Klipp, Alastair G. Mcewan
    Abstract:

    Expression of the dimethylsulfoxide respiratory (dor) operon of Rhodobacter is regulated by oxygen, light intensity and availability of substrate. Since dimethylsulfoxide reductase contains a pterin molybdenum cofactor, the role of molybdate in the regulation of dor operon expression was investigated. In this report we show that the molybdate-responsive transcriptional regulator, MopB, and molybdate are essential for maximal dimethylsulfoxide reductase activity and expression of a dorA::lacZ transcriptional fusion in Rhodobacter Capsulatus. In contrast, mop genes are not required for the expression of the periplasmic nitrate reductase or xanthine dehydrogenase in R. Capsulatus under conditions of molybdenum sufficiency. This is the first report demonstrating a clear functional difference between the ModE homologues MopB and MopA in this bacterium. The results suggest that MopA is primarily involved in the regulation of nitrogen fixation gene expression in response to molybdate while MopB has a role in nitrogen fixation and dimethylsulfoxide respiration.

  • Characterization of a molybdenum cofactor biosynthetic gene cluster in Rhodobacter Capsulatus which is specific for the biogenesis of dimethylsulfoxide reductase.
    Microbiology, 1999
    Co-Authors: Peter S. Solomon, Anthony L. Shaw, Graeme R. Hanson, I. Lane, Tracy Palmer, Alastair G. Mcewan
    Abstract:

    The DMSO reductase of Rhodobacter Capsulatus contains a pterin molybdenum cofactor (Moco) and is located in the periplasm. DNA sequence analysis identified four genes involved in the biosynthesis of the Moco (moaA, moaD, moeB and moaC) immediately downstream of the dor (DMSO respiratory) gene cluster. Rhodobacter Capsulatus MoaA was expressed in Escherichia coli as a His6-tagged protein. Although, the expressed protein formed inclusion bodies, EPR spectroscopy showed that MoaA contains a [3Fe-4S] cluster. A moaA mutant was constructed and its phenotype indicates that the Moco biosynthetic gene cluster downstream of the dor operon is specific for the biogenesis of DMSO reductase. Two forms of DMSO reductase were purified by immunoaffinity chromatography from the moaA mutant. A mature form of DMSO reductase was located in the periplasm and a precursor form was found in the cytoplasm.

  • Asymmetric reduction of racemic sulfoxides by dimethyl sulfoxide reductases from Rhodobacter Capsulatus, Escherichia coli and Proteus species.
    Microbiology, 1998
    Co-Authors: Steven P. Hanlon, Anthony L. Shaw, D.l. Graham, Philip J. Hogan, Robert A. Holt, Christopher David Reeve, Alastair G. Mcewan
    Abstract:

    The enantioselective reduction of racemic sulfoxides by dimethyl sulfoxide reductases from Rhodobacter Capsulatus, Escherichia coli, Proteus mirabilis and Proteus vulgaris was investigated. Purified dimethyl sulfoxide reductase from Rhodobacter Capsulatus catalysed the selective removal of (S)-methyl p-tolyl sulfoxide from a racemic mixture of methyl p-tolyl sulfoxide and resulted in an 88% recovery of enantiomerically pure (R)-methyl p-tolyl sulfoxide. Rhodobacter Capsulatus was shown to be able to grow photoheterotrophically in the presence of certain chiral sulfoxides under conditions where a sulfoxide is needed as an electron sink. Whole cells of Rhodobacter Capsulatus were shown to catalyse the enantioselective reduction of methyl p-tolyl sulfoxide, ethyl 2-pyridyl sulfoxide, methylthiomethyl methyl sulfoxide and methoxymethyl phenyl sulfoxide. Similarly, whole cells of Escherichia coli, Proteus mirabilis and Proteus vulgaris reduced these sulfoxides but with opposite enantioselectivity.

  • Cloning and sequence analysis of the dimethylsulfoxide reductase structural gene from Rhodobacter Capsulatus
    Biochimica et Biophysica Acta, 1996
    Co-Authors: Anthony L. Shaw, Graeme R. Hanson, Alastair G. Mcewan
    Abstract:

    The dimethylsulfoxide reductase structural gene (dorA) of Rhodobacter Capsulatus was cloned from a λ expression library. The nucleotide sequence of the dorA gene was determined and it was found to encode a protein of 825 amino acids. Comparison of the deduced amino-acid sequence of DorA with N-terminal sequence of purified dimethylsulfoxide reductase from Rhodobacter Capsulatus showed that the pre-protein possesses a 41-amino-acid N-terminal signal polypeptide. All of the conserved segments which have been described in bacterial enzymes which bind molybdopterin guanine dinucleotide (Berks, B.C., Ferguson, S.J., Moir, J.W.B. and Richardson, D.J. (1995) Biochim. Biophys. Acta 1232, 97-173) were identified in Rhodobacter Capsulatus dimethylsulfoxide reductase.

  • Isolation, characterisation and expression of the bacterioferritin gene of Rhodobacter Capsulatus
    Fems Microbiology Letters, 1996
    Co-Authors: Christopher N. Penfold, Alastair G. Mcewan, Patricia L. Ringeling, Sharon L. Davy, Geoffrey R. Moore, Stephen Spiro
    Abstract:

    The nucleotide sequence of the Rhodobacter Capsulatus bacterioferritin gene (bfr) was determined and found to encode a protein of 161 amino acids with a predicted molecular mass of 18 174 Da. The molecular mass of the purified protein was estimated to be 18 176.06 ± 0.80 Da by electrospray mass spectrometry. The bfr gene was introduced into an expression vector, and bacterioferritin was produced to a high level in Escherichia coli. The amino acids which are involved in haem ligation, and those which provide ligands in the binuclear metal centre in bacterioferritin from E. coli are conserved in the R. Capsulatus protein. The sequences of bacterioferritins, ferritin-like proteins, and proteins similar to Dps of E. coli are compared, and membership of the bacterioferritin family re-evaluated.