The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform

John R. Sokatch - One of the best experts on this subject based on the ideXlab platform.

Yasutaro Fujita - One of the best experts on this subject based on the ideXlab platform.

  • gnt operon mediated by the CcpA protein. Catabolite Repression of the Bacillus subtilis
    2013
    Co-Authors: Yasutaro Fujita, Yasuhiko Miwa
    Abstract:

    Repression.In the genusBacillus, Catabolite Repression is observed notonly in adaptive enzyme synthesis but also at the onset ofsporulation (4). Catabolite Repression of carbon utilizationenzymes might be explained in part by inducer exclusion,becausemanyoftheseenzymesareinducedbytheirsubstrates.Recently, the cis-acting sequences responsible for Catabolite

  • Catabolite Repression of the Bacillus subtilis gnt operon exerted by two Catabolite‐responsive elements
    Molecular microbiology, 1997
    Co-Authors: Yasuhiko Miwa, Kazuya Nagura, Susumu Eguchi, Hirokazu Fukuda, Josef Deutscher, Yasutaro Fujita
    Abstract:

    Summary Catabolite Repression of Bacillus subtilis catabolic operons is supposed to occur via a negative regulatory mechanism involving the recognition of a cis-acting Catabolite-responsive element (cre) by a complex of CcpA, which is a member of the GalR-LacI family of bacterial regulatory proteins, and the seryl-phos-phorylated form of HPr (P-ser-HPr), as verified by recent studies on Catabolite Repression of the gnt operon. Analysis of the gnt promoter region by deletions and point mutations revealed that in addition to the ere in the first gene (gntR) of the gnt operon (credown), this operon contains another ere located in the promoter region (creup). A translational gntR-lacZ fusion expressed under the control of various combinations of wild-type and mutant credown and creup was integrated into the chromosomal amyE locus, and then Catabolite Repression of p-galac-tosidase synthesis in the resultant integrants was examined. The in vivo results implied that Catabolite Repression exerted by creup was probably independent of Catabolite Repression exerted by credown; both creup and credown Catabolite Repression involved CcpA. Catabolite Repression exerted by creup was independent of P-ser-HPr, and Catabolite Repression exerted by credown was partially independent of P-ser-HPr. DNase I footprinting experiments indicated that a complex of CcpA and P-ser-HPr did not recognize creup, in contrast to its specific recognition of credown. However, CcpA complexed with glucose-6-phosphate specifically recognized creup as well as credown, but the physiological significance of this complexing is unknown.

  • Catabolite Repression of the Bacillus subtilis gnt operon mediated by the CcpA protein.
    Journal of bacteriology, 1994
    Co-Authors: Yasutaro Fujita, Yasuhiko Miwa
    Abstract:

    Inducer exclusion was not important in Catabolite Repression of the Bacillus subtilis gnt operon. The CcpA protein (also known as AlsA) was found to be necessary for Catabolite Repression of the gnt operon, and a mutation (crsA47, which is an allele of the sigA gene) partially affected this Catabolite Repression.

  • Promoter-independent Catabolite Repression of the Bacillus subtilis gnt operon.
    Journal of biochemistry, 1993
    Co-Authors: Yasuhiko Miwa, Yasutaro Fujita
    Abstract:

    The mechanism underlying Catabolite Repression in Bacillus species remains unknown. A recent study of the promoter-independent Catabolite Repression of the gnt operon implicated a consensus sequence (ATTGAAAG) in Catabolite Repression in the genus Bacillus. The introduction of base-substitutions into the ATTGAAAG sequence in the chromosomal gnt operon affected Catabolite Repression of the gnt operon. Deletion analysis indicated that the ATTGAAAG sequence is probably part of a cis sequence necessary for the promoter-independent Catabolite Repression of the gnt operon. Furthermore, we subjected gnt transcripts synthesized with and without glucose to S1 nuclease and slot blotting analyses. The results indicated that the gnt transcripts decreased in the region (+93 to +203; +1, the transcription initiation nucleotide) only in the presence of glucose. Mechanisms underlying this promoter-independent Catabolite Repression are discussed.

Yasuhiko Miwa - One of the best experts on this subject based on the ideXlab platform.

  • gnt operon mediated by the CcpA protein. Catabolite Repression of the Bacillus subtilis
    2013
    Co-Authors: Yasutaro Fujita, Yasuhiko Miwa
    Abstract:

    Repression.In the genusBacillus, Catabolite Repression is observed notonly in adaptive enzyme synthesis but also at the onset ofsporulation (4). Catabolite Repression of carbon utilizationenzymes might be explained in part by inducer exclusion,becausemanyoftheseenzymesareinducedbytheirsubstrates.Recently, the cis-acting sequences responsible for Catabolite

  • Catabolite Repression of the Bacillus subtilis gnt operon exerted by two Catabolite‐responsive elements
    Molecular microbiology, 1997
    Co-Authors: Yasuhiko Miwa, Kazuya Nagura, Susumu Eguchi, Hirokazu Fukuda, Josef Deutscher, Yasutaro Fujita
    Abstract:

    Summary Catabolite Repression of Bacillus subtilis catabolic operons is supposed to occur via a negative regulatory mechanism involving the recognition of a cis-acting Catabolite-responsive element (cre) by a complex of CcpA, which is a member of the GalR-LacI family of bacterial regulatory proteins, and the seryl-phos-phorylated form of HPr (P-ser-HPr), as verified by recent studies on Catabolite Repression of the gnt operon. Analysis of the gnt promoter region by deletions and point mutations revealed that in addition to the ere in the first gene (gntR) of the gnt operon (credown), this operon contains another ere located in the promoter region (creup). A translational gntR-lacZ fusion expressed under the control of various combinations of wild-type and mutant credown and creup was integrated into the chromosomal amyE locus, and then Catabolite Repression of p-galac-tosidase synthesis in the resultant integrants was examined. The in vivo results implied that Catabolite Repression exerted by creup was probably independent of Catabolite Repression exerted by credown; both creup and credown Catabolite Repression involved CcpA. Catabolite Repression exerted by creup was independent of P-ser-HPr, and Catabolite Repression exerted by credown was partially independent of P-ser-HPr. DNase I footprinting experiments indicated that a complex of CcpA and P-ser-HPr did not recognize creup, in contrast to its specific recognition of credown. However, CcpA complexed with glucose-6-phosphate specifically recognized creup as well as credown, but the physiological significance of this complexing is unknown.

  • Catabolite Repression of the Bacillus subtilis gnt operon mediated by the CcpA protein.
    Journal of bacteriology, 1994
    Co-Authors: Yasutaro Fujita, Yasuhiko Miwa
    Abstract:

    Inducer exclusion was not important in Catabolite Repression of the Bacillus subtilis gnt operon. The CcpA protein (also known as AlsA) was found to be necessary for Catabolite Repression of the gnt operon, and a mutation (crsA47, which is an allele of the sigA gene) partially affected this Catabolite Repression.

  • Promoter-independent Catabolite Repression of the Bacillus subtilis gnt operon.
    Journal of biochemistry, 1993
    Co-Authors: Yasuhiko Miwa, Yasutaro Fujita
    Abstract:

    The mechanism underlying Catabolite Repression in Bacillus species remains unknown. A recent study of the promoter-independent Catabolite Repression of the gnt operon implicated a consensus sequence (ATTGAAAG) in Catabolite Repression in the genus Bacillus. The introduction of base-substitutions into the ATTGAAAG sequence in the chromosomal gnt operon affected Catabolite Repression of the gnt operon. Deletion analysis indicated that the ATTGAAAG sequence is probably part of a cis sequence necessary for the promoter-independent Catabolite Repression of the gnt operon. Furthermore, we subjected gnt transcripts synthesized with and without glucose to S1 nuclease and slot blotting analyses. The results indicated that the gnt transcripts decreased in the region (+93 to +203; +1, the transcription initiation nucleotide) only in the presence of glucose. Mechanisms underlying this promoter-independent Catabolite Repression are discussed.

Wolfgang Hillen - One of the best experts on this subject based on the ideXlab platform.

  • Mutations in Catabolite Control Protein CcpA Separating Growth Effects from Catabolite Repression
    Journal of bacteriology, 1999
    Co-Authors: Elke Küster, Tanja Hilbich, Michael K. Dahl, Wolfgang Hillen
    Abstract:

    Carbon Catabolite Repression in Bacillus megaterium is mediated by the transcriptional regulator CcpA. A chromosomal deletion of ccpA eliminates Catabolite Repression and reduces the growth rate on glucose. We describe four single-amino-acid mutations in CcpA which separate the growth effect from Catabolite Repression, suggesting distinct regulatory pathways for these phenotypes.

  • Carbon Catabolite Repression in bacteria.
    Current opinion in microbiology, 1999
    Co-Authors: Jörg Stülke, Wolfgang Hillen
    Abstract:

    Carbon Catabolite Repression (CCR) is a regulatory mechanism by which the expression of genes required for the utilization of secondary sources of carbon is prevented by the presence of a preferred substrate. This enables bacteria to increase their fitness by optimizing growth rates in natural environments providing complex mixtures of nutrients. In most bacteria, the enzymes involved in sugar transport and phosphorylation play an essential role in signal generation leading through different transduction mechanisms to Catabolite Repression. The actual mechanisms of regulation are substantially different in various bacteria. The mechanism of lactose-glucose diauxie in Escherichia coli has been reinvestigated and was found to be caused mainly by inducer exclusion. In addition, the gene encoding HPr kinase, a key component of CCR in many bacteria, was discovered recently.

  • A NOVEL PROTEIN KINASE THAT CONTROLS CARBON Catabolite Repression IN BACTERIA
    Molecular microbiology, 1998
    Co-Authors: Jonathan Reizer, Milton H. Saier, Jörg Stülke, C Hoischen, Friedrich Titgemeyer, Carlo Rivolta, Ralf Rabus, Dimitri Karamata, Wolfgang Hillen
    Abstract:

    HPr(Ser) kinase is the sensor in a multicomponent phosphorelay system that controls Catabolite Repression, sugar transport and carbon metabolism in Gram-positive bacteria. Unlike most other protein kinases, it recognizes the tertiary structure in its target protein, HPr, a phosphocarrier protein of the bacterial phosphotransferase system and a transcriptional cofactor controlling the phenomenon of Catabolite Repression. We have identified the gene (ptsK) encoding this serine/threonine protein kinase and characterized the purified protein product. Orthologues of PtsK have been identified only in bacteria. These proteins constitute a novel family unrelated to other previously characterized protein phosphorylating enzymes. The Bacillus subtilis kinase is shown to be allosterically activated by metabolites such as fructose 1,6-bisphosphate and inhibited by inorganic phosphate. In contrast to wild-type B. subtilis, the ptsK mutant is insensitive to transcriptional regulation by Catabolite Repression. The reported results advance our understanding of phosphorylation-dependent carbon control mechanisms in Gram-positive bacteria.

  • Contributions of Xy1R, CcpA and HPr to Catabolite Repression of the xyl operon in Bacillus subtilis
    FEMS Microbiology Letters, 1995
    Co-Authors: Michael K. Dahl, Wolfgang Hillen
    Abstract:

    The xyl operon of Bacillus subtilis is regulated at the level of transcription by xylose induction via the Xyl repressor and by Catabolite Repression. We have investigated the influence of ccpA, ptsH, ptsG and xylR mutations on Catabolite Repression of xylA expression. The results indicate that full glucose Repression of the xyl operon requires CcpA, Hpr and XylR. In contrast, fructose Repression depends on CcpA and Hpr, but not on XylR. The ptsH1 mutation relieves Catabolite Repression only partially, suggesting the possibility that other presently unknown signals are sensed by CcpA.

Kathryn L. Hester - One of the best experts on this subject based on the ideXlab platform.