Mitochondrial low-molecular-weight heat-shock proteins and the tolerance of cereal mitochondria to hyperthermia

Relationships between the appearance of low-molecular-weight heat-shock pro teins (LMW HSPs) in maize, winter wheat. and winter rye mitochondria and th e tolerance of the mitochondria to hyperthermia (42 degreesC, 3 h) were stu died using one-dimensional SDS-PAGE, immunochemical methods, and polarograp hy, Heat shock inhibited respiration to a greater extent in the wheat and r ye than in the maize mitochondria. A single 20-kD LMW HSP was found both in side and on the surface of mitochondria isolated from heat-treated wheat an d rye seedlings. After heating maize seedlings, two LMW HSPs (28 and 23 kD) appeared inside the mitochondria, and three proteins (22, 20, and 19 kD) a ppeared on their surface. We suppose that the latter three proteins play an essential role in the protection of mitochondria from hyperthermic damage. It seems likely that the diversity of the hyperthermia-induced LMW HSPs in plant mitochondria affects their thermal stability.