Chlamydomonas plastid chaperonin subunits expressed in E. coli can interact with one another inside the bacterial cell and putatively confer enhanced tolerance toward singlet oxygen

Abstract

Chaperonins are a group of molecular chaperones with a primary role in assisting folding of other proteins. The most recognized member of the chaperonins is the GroEL/GroES complex. While most eubacteria as well as mitochondria of eukaryotes have a single copy of the groEL gene, plants and algae contain multiple versions that have been shown to assemble into a hetero-oligomeric complex. We report here evidence suggesting that Chlamydomonas plastid chaperonin 60 subunits, when expressed in E. coli cells, can interact with each other and assemble into a highmolecular- weight protein complex. Stress challenge assays also revealed that exogenous expression of all alpha, beta1, and beta2 subunits of Chlamydomonas chaperonin 60 in E. coli also confer additional tolerance and recovery of cells from singlet oxygen stress.