Corn mitochondrial protein synthesis in response to heat shock

Corn (Zea mays L., W23(N), OH43(N), and reciprocal single cross hybrid) seedling mitochondria respond to a 10°C temperature shift (27-37°C) by incorporating a greater amount of [³⁵S]methionine into acid-insoluble material than mitochondria incubated at the original growing temperature (27°C). This increase is in part manifested in the enhanced synthesis of a 52 kilodaltons protein. At both temperatures mitochondria of two inbreds and their reciprocal hybrids synthesize normal (N) cytoplasm proteins sensitive to chloramphenicol and insensitive to cyclohexamide treatment. The 52 kilodaltons protein is found in the supernatants of pelleted (15,000g, 5 min) mitochondria after heat shock. The role of this protein in the heat shock response is discussed in light of the implication of mitochondria as the primary cellular target to temperature stress.