A 16.6-KILODALTON PROTEIN IN THE CYANOBACTERIUM SYNECHOCYSTIS SP. PCC-6803 PLAYS A ROLE IN THE HEAT-SHOCK RESPONSE

The low molecular weight (LMW) heat shock protein (HSP) gene hsp16.6 w as identified and cloned from the unicellular cyanobacterium Synechocy stis sp. PCC 6803 through comparisons of genomic sequences and conserv ed gene sequences of the LMW HSPs. Hsp16.6 was isolated using PCR and cloned into the pGEMT plasmid. Hsp16.6 showed a significant increase i n transcription after heat shock at 42 degrees C that indicated hsp16. 6 was a heat shock gene. To determine the role that hsp16.6 plays in t he heat shock response, a mutant Synechocystis cell line was generated . Cell growth and oxygen evolution rates of wild type and mutant cells were compared after heat shock. Results showed significantly decrease d cell growth rates and a 40% reduction in oxygen evolution rates in m utants after heat shock treatments. These data indicate a protective r ole for hsp16.6 in the heat shock response.