Abstract
Previously, we reported that the constitutive expression of HspA, a small heat-shock protein (HSP) increased thermal resistance of PSII and protected phycocyanin from heat-induced photo-bleaching in Synechococcus sp. PCC 7942. These results indicate that a small HSP plays a role in the protection of the light harvesting phycobilisome and the electron transport system under heat stress.
In the present study, we examined whether molecular chaperones such as small HSP and GroEL may interact with phycobiliproteins. We purified phycobilisome from the mutant by the sucrose density gradient ultracentrifugation method, resulting in the separation of the heavy and light fractions containing phycobiliproteins. The heavy fraction contained purified phycobilisomes. The light fraction contained GroEL and HspA as well as phycobiliproteins. The dissociation of phycobilisome may have produced an intermediate complex which interacts with these molecular chaperones. In vitro experiments are in progress to show the physical interaction between molecular chaperones and phycobiliproteins.
