Genetic and biochemical analysis of dnaJ3 gene in the Cyanobacuterium Synechococcus elongatus PCC 7942.

Abstract

The genome of cyanobacterium Synechococcus elongatus PCC 7942 contains three dnaK and four dnaJ homologs. Among them, DnaJ3 is essential for normal growth and localized onto the thylakoid membrane as is DnaK3. In order to elucidate specific functions of DnaJ3, we carried out genetic analyses. Using PCR-mutagenesis to introduce point mutations into the C-terminal region of dnaJ3, a temperature sensitive mutant carrying a missense mutation F193L (t598c) was isolated. Moreover, we obtained several suppressor mutants from F193L strain and mapped their mutations in syfpcc7942_2440 (pnp) and syfpcc7942_1999 (rbp2) genes. When compared to the wild type strain, dnaJ3 mRNA of the F193L strain was more stable. Here we discuss the involvement between of the dnaJ3 mRNA stability with the temperature sensitivity of growth.