Specific and promiscuous functions of multiple DnaJ proteins in Synechocystis sp. PCC 6803

Cyanobacterial genomes typically encode multiple Hsp70 (DnaK) and Hsp40 (DnaJ) chaperones, and in the genome of the cyanobacterium Synechocystis PCC 6803, three DnaK proteins are encoded together with seven DnaJ proteins. While only two of the DnaJ proteins can complement the growth defect of an Escherichia coli ΔdnaJ strain, only disruption of the dnaJ gene sll0897 resulted in a growth defect at elevated temperatures. Based on the domain structure and the phenotype observed following disruption of the encoding gene, Sll0897 can be classified as a canonical heat-shock protein in Synechocystis. Furthermore, most dnaJ genes could be deleted individually, whereas disruption of the gene encoding the DnaJ Sll1933 failed, which suggests an essential, yet undefined, function for Sll1933. Since after deletion of the remaining dnaJ genes the phenotypes were not altered, the functions of these DnaJs either are not critical or are taken over by the remaining DnaJs. Nevertheless, only the two dnaJ genes sll0909 and sll1384 could be disrupted in combination, suggesting physiological functions for the two encoded proteins which either are not overlapping and/or can be fulfilled by the remaining DnaJs in the double-disruption strain. Taken together, the present analysis indicates specific and promiscuous functions for multiple DnaJ proteins in Synechocystis.

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Expression of a gene encoding a 16.9-kDa heat-shock protein, Oshsp16.9, in Escherichia coli enhances thermotolerance

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.94.20.10967 ◽

1997 ◽

Vol 94 (20) ◽

pp. 10967-10972 ◽

Cited By ~ 95

Author(s):

C.-H. Yeh ◽

P.-F. L. Chang ◽

K.-W. Yeh ◽

W.-C. Lin ◽

Y.-M. Chen ◽

...

Keyword(s):

Escherichia Coli ◽

Heat Shock ◽

Heat Shock Protein ◽

Gene Encoding

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Regulation and Mechanism of Action of the Small Heat Shock Protein from the Hyperthermophilic ArchaeonPyrococcus furiosus

Journal of Bacteriology ◽

10.1128/jb.183.17.5198-5202.2001 ◽

2001 ◽

Vol 183 (17) ◽

pp. 5198-5202 ◽

Cited By ~ 41

Author(s):

Pongpan Laksanalamai ◽

Dennis L. Maeder ◽

Frank T. Robb

Keyword(s):

Escherichia Coli ◽

Heat Shock ◽

Heat Shock Protein ◽

Mechanism Of Action ◽

Pyrococcus Furiosus ◽

Small Heat Shock Protein ◽

Control Culture ◽

Gene Encoding ◽

E Coli

ABSTRACT The small heat shock protein (sHSP) from the hyperthermophilePyrococcus furiosus was specifically induced at the level of transcription by heat shock at 105°C. The gene encoding this protein was cloned and overexpressed in Escherichia coli. The recombinant sHSP prevented the majority of E. coli proteins from aggregating in vitro for up to 40 min at 105°C. The sHSP also prevented bovine glutamate dehydrogenase from aggregating at 56°C. Survivability of E. colioverexpressing the sHSP was enhanced approximately sixfold during exposure to 50°C for 2 h compared with the control culture, which did not express the sHSP. Apparently, the sHSP confers a survival advantage on mesophilic bacteria by preventing protein aggregation at supraoptimal temperatures.

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