Protection of psbAII transcript from ribonuclease degradation in vitro by DnaK2 and DnaJ2 chaperones of the cyanobacterium Synechococcus elongatus PCC 7942

Three dnaK and four dnaJ genes have been identified in the genome of cyanobacterium Syneehoeoceus elongatus PCC 7942. Our comprehensive analysis of yeast two-hybrid screening revealed a specific interaction among DnaK2, DnaJ2, and RNase E, an essential endoribonuclease. We examined the effects of DnaK2 and DnaJ2 on RNase E activity by monitoring the digestion of psbAII transcript in vitro. The addition of DnaK2 and DnaJ2 obviously inhibited RNase E activity in an ATP-dependent manner. These results suggest that DnaK2 and DnaJ2 are involved in RNA degradation through interaction with RNase E.