A heat shock protein is encoded within mitochondria of higher plants

A temperature shift from 25 to 41 degrees C initiates the synthesis of a specific set of proteins in maize, including a peptide of 60 kilodaltons. Using an in vitro mitochondrial protein synthesizing system, we provide evidence that this 60-kDa heat shock protein is encoded within the organelle. Further support for this heat-induced protein being encoded within mitochondria is that its synthesis is inhibited in whole seedlings by chloramphenicol. This 60-kDa heat shock protein is induced in all lines of maize we examined. Additionally, a heat-induced peptide of similar size (62 kDa) can be detected in isolated mitochondria of a dicot plant, Brassica campestris. The function of the heat shock protein encoded within the mitochondria remains unknown.