Mitochondrial malate dehydrogenases in Brassica napus: altered protein patterns in different nuclear mitochondrial combinations.

Two-dimensional analyses of mitochondrial proteins of Brassica napus revealed a set of differences in patterns of mitochondrial matrix proteins isolated from different nuclear backgrounds. One of these varying proteins was identified as mitochondrial malate dehydrogenase (mMDH;EC 1.1.1.37) by homology analyses of the partial amino acid sequence. Immunological detection identified additional mMDH subunits and detected different patterns of mMDH subunits in two distinct mitochondria types although they were isolated from plants with the same nuclear genotype. These differences are also reflected in isozym patterns, whereas Southern analyses showed no alteration in genome structure. Therefore mitochondria type-specific mMDH modifications are possible.