Abstract
We examined the expression and the function of the DnaK chaperone family in the photoautotrophic cyanobacterium, Synechocystis PCC 6803. Surprisingly, only one of the three dnaK genes was transcribed either under normal or heat shock conditions. Their predicted cochaperones (four dnaJs and one grpE) proved to be uninducible under our experimental conditions. Attempts to inactivate the active dnaK2 has failed, indicating that the gene is essential. The partial mutant displayed lower inducibility of chaperones (especially GroEL and HSP17) both at mRNA and protein levels upon heat shock. The mutant showed temperature sensitive phenotype, but was able to acquire thermotolerance.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacterial Proteins / biosynthesis
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Bacterial Proteins / genetics
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Cyanobacteria / genetics
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Cyanobacteria / growth & development
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Cyanobacteria / metabolism*
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Gene Expression Regulation, Bacterial
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Genes, Bacterial
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HSP40 Heat-Shock Proteins
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HSP70 Heat-Shock Proteins / biosynthesis*
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HSP70 Heat-Shock Proteins / genetics
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HSP70 Heat-Shock Proteins / physiology*
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Heat-Shock Proteins / biosynthesis
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Heat-Shock Proteins / genetics
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Heat-Shock Response
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Multigene Family
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Mutation
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Photosynthesis
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RNA, Bacterial / biosynthesis
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Transcription, Genetic
Substances
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Bacterial Proteins
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GrpE protein, Bacteria
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HSP40 Heat-Shock Proteins
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HSP70 Heat-Shock Proteins
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Heat-Shock Proteins
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RNA, Bacterial