6533b86dfe1ef96bd12c979d

RESEARCH PRODUCT

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

subject

description

Cyanobacterial genomes typically encode multiple Hsp70 (DnaK) and Hsp40 (DnaJ) chaperones, and in the genome of the cyanobacteriumSynechocystisPCC 6803, three DnaK proteins are encoded together with seven DnaJ proteins. While only two of the DnaJ proteins can complement the growth defect of anEscherichia coliΔdnaJstrain, only disruption of thednaJgenesll0897resulted 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 inSynechocystis. Furthermore, mostdnaJgenes 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 remainingdnaJgenes 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 twodnaJgenessll0909andsll1384could 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 inSynechocystis.