Effect of heat shock on protein synthesis in the cyanobacterium Synechococcus sp. strain PCC 6301

The response to heat shock at 47 degrees C was examined in the cyanobacterium (blue-green alga) Synechococcus sp. strain PCC 6301. On heat shock, the growth of the cells decreased and they preferentially synthesized a limited number of polypeptides. The rate of synthesis of these proteins increased markedly in the early period of temperature shift up and gradually decreased afterwards. Among the proteins greatly affected by temperature shift up were those with apparent molecular weights of 91,000 (91K), 79K, 78K, 74K, 65K, 64K, 61K, 49K, 45K, 24K, 22K, 18K, 16K, 14K, 12K, and 11.4K, based on their mobilities in sodium dodecyl sulfate-polyacrylamide gels. From these initial studies on Synechococcus sp. strain PCC 6301 we conclude that in cyanobacteria a heat shock response similar to that known to occur in other eucaryotes and procaryotes might exist.