Abstract
The cyanobacterial genomes contain two homologues of the groEL gene, groEL1 and groEL2. The groEL1 gene forms an operon with groES whereas groEL2 is not accompanied by groES. Plant chloroplasts also possess two types of Cpn60 which are GroEL homologues, known to form a hetero-oligomeric assembly. The present study is being conducted to unveil whether the cyanobacterial GroELs can also show a hetero-oligomeric assembly. Native polyacrylamide gel electrophoresis showed that in Synechococcus elongatus PCC 7942, unlike in E. coli, GroEL1 and GroEL2 do not form a tetradecamer.. In vitro the cyanobacterial GroEL1 formed smaller oligomers such as a heptamer, while GroEL2 formed only a trimer. To investigate hetero-oligomeric interaction, a pull-down assay was conducted using Thermosynechococcus elongatus His-GroEL1 and S.vulcanus GroEL1 or GroEL2. The His-GroEL1 formed a hetero-oligomer with the GroEL2. The distinct in vitro properties of the cyanobacterial oligomers implicate physiological significance which may be required under environmental stress.
