Only one dnaK homolog, dnaK2, is active transcriptionally and is essential in Synechocystis

Viktória Varvasovszki, Attila Glatz, Natalia Shigapova, Katalin Jósvay, László Vígh, Ibolya Horváth

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17 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)641-648
Number of pages8
JournalBiochemical and biophysical research communications
Issue number3
Publication statusPublished - Jun 6 2003



  • DnaJ homologs grpE
  • DnaK
  • Heat stress
  • Synechocystis PCC 6803

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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