Abstract
Molecular chaperones DnaK and DnaJ are widely known to act as partner proteins during proper folding of various proteins. In cyanobacteria Synechococcus sp. PCC7942, these chaperones were found to exist as multi-gene family with 3 dnaK (dnaK1, dnaK2, dnaK3) and 4 dnaJ (dnaJ1, dnaJ2, dnaJ3, dnaJ4) homologs. We have previously reported that dnaJ1, dnaJ2 and dnaJ3 are essential for nomal growth, with the latter exist as partner of the dnaK3 and co-localize of the thylakoid membrane.
In order to elucidate other specific function of DnaJ3, we carried out genetic analysis. Using PCR-mutagenesis to introduce point mutation in non-conserved C-terminal region, we were able to isolate a temperature sensitive mutant resulting from mutation F193L. Moreover, two of the suppressor mutations mapped severally in the Rbp2 (syc2097) or PNPase (syc1666) . We are currently analyzing the possible mechanism involved in the suppression of DnaJ3 mutation.
