title: Only one dnaK homolog, dnaK2, is active transcriptionally and is essential in Synechocystis.
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.
authors.affiliation: Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary.
authors.forename: Viktória
authors.initials: V
authors.lastname: Varvasovszki
authors.forename: Attila
authors.initials: A
authors.lastname: Glatz
authors.forename: Natalia
authors.initials: N
authors.lastname: Shigapova
authors.forename: Katalin
authors.initials: K
authors.lastname: Jósvay
authors.forename: László
authors.initials: L
authors.lastname: Vígh
authors.forename: Ibolya
authors.initials: I
authors.lastname: Horváth
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D000458:Cyanobacteria / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D018869:Heat-Shock Response; D005810:Multigene Family; D009154:Mutation; D010788:Photosynthesis; D012329:RNA, Bacterial / Q000096:biosynthesis; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C068113:GrpE protein, Bacteria; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D012329:RNA, Bacterial