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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
1
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pubmed:dateCreated |
2001-3-13
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pubmed:abstractText |
The hydH/G genes from Escherichia coli code for a two-component regulatory system that has been implicated in the regulation of hydrogenase 3 formation. In a detailed study of the function of HydH/G employing hycA'-'lacZ reporter gene fusions, it was shown that HydH/G indeed led to a stimulation of activation of the hycA promoter responsible for hydrogenase 3 synthesis but only when hydG is overexpressed from a plasmid in a strain lacking FhlA. Since the stimulation was not observed with an fdhF'-'lacZ fusion, and since it was independent from a functional hydH gene product, it must be considered as unspecific cross-talk. An extensive search for the actual physiological signal of HydH/G showed that the system responds to high concentrations of zinc or lead in the medium. Expression of zraP, a gene inversely oriented to hydH/G whose product seems to be involved in acquisition of tolerance to high Zn(2+) concentrations, is stimulated by high Zn(2+) and Pb(2+) concentrations and this stimulation requires both HydH and HydG. Purified HydG in the presence of phosphoryl donors binds to a region within the zraP-hydHG intergenic region that is characterised by two inverted repeats separated by a 14 bp spacer. Putative -12/-24 sigma(54)-dependent promoter motifs are present upstream of both the zraP and the hydHG transcriptional units; in accordance, transcription of zraP is strictly dependent on the presence of a functional rpoN gene. The expression of hydH/G is autoregulated: high Zn(2+) and Pb(2+) concentrations lead to a significant increase of the HydG protein content which took place only in a hydH(+) genetic background. Since HydH binds to membranes tightly, it is assumed that the HydH/G system senses high periplasmic Zn(2+) and Pb(2+) concentrations and contributes to metal tolerance by activating the expression of zraP. The redesignation of hydH/G as zraS/R is suggested.
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Bacterial Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/DNA, Bacterial,
http://linkedlifedata.com/resource/pubmed/chemical/DNA-Binding Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/DNA-Directed RNA Polymerases,
http://linkedlifedata.com/resource/pubmed/chemical/Escherichia coli Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Formate Dehydrogenases,
http://linkedlifedata.com/resource/pubmed/chemical/Hydrogenase,
http://linkedlifedata.com/resource/pubmed/chemical/Lead,
http://linkedlifedata.com/resource/pubmed/chemical/Multienzyme Complexes,
http://linkedlifedata.com/resource/pubmed/chemical/RNA Polymerase Sigma 54,
http://linkedlifedata.com/resource/pubmed/chemical/Sigma Factor,
http://linkedlifedata.com/resource/pubmed/chemical/Trans-Activators,
http://linkedlifedata.com/resource/pubmed/chemical/Zinc,
http://linkedlifedata.com/resource/pubmed/chemical/formate hydrogenlyase,
http://linkedlifedata.com/resource/pubmed/chemical/rpoN protein, E coli,
http://linkedlifedata.com/resource/pubmed/chemical/zraP protein, E coli
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pubmed:status |
MEDLINE
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pubmed:month |
Mar
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pubmed:issn |
0022-2836
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pubmed:author |
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pubmed:copyrightInfo |
Copyright 2001 Academic Press.
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pubmed:issnType |
Print
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pubmed:day |
16
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pubmed:volume |
307
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
93-105
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pubmed:dateRevised |
2009-11-19
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pubmed:meshHeading |
pubmed-meshheading:11243806-Bacterial Proteins,
pubmed-meshheading:11243806-Base Sequence,
pubmed-meshheading:11243806-Cloning, Molecular,
pubmed-meshheading:11243806-DNA, Bacterial,
pubmed-meshheading:11243806-DNA Footprinting,
pubmed-meshheading:11243806-DNA-Binding Proteins,
pubmed-meshheading:11243806-DNA-Directed RNA Polymerases,
pubmed-meshheading:11243806-Escherichia coli,
pubmed-meshheading:11243806-Escherichia coli Proteins,
pubmed-meshheading:11243806-Formate Dehydrogenases,
pubmed-meshheading:11243806-Gene Expression Regulation, Bacterial,
pubmed-meshheading:11243806-Hydrogenase,
pubmed-meshheading:11243806-Lead,
pubmed-meshheading:11243806-Molecular Sequence Data,
pubmed-meshheading:11243806-Molecular Weight,
pubmed-meshheading:11243806-Multienzyme Complexes,
pubmed-meshheading:11243806-RNA Polymerase Sigma 54,
pubmed-meshheading:11243806-Sequence Homology, Nucleic Acid,
pubmed-meshheading:11243806-Sigma Factor,
pubmed-meshheading:11243806-Trans-Activators,
pubmed-meshheading:11243806-Transcription, Genetic,
pubmed-meshheading:11243806-Zinc
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pubmed:year |
2001
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pubmed:articleTitle |
The hydH/G Genes from Escherichia coli code for a zinc and lead responsive two-component regulatory system.
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pubmed:affiliation |
Lehrstuhl für Mikrobiologie der Universität München, Maria-Ward-Str. 1a, D-80638 Munich, Germany.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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