S1 and S2, the linear mitochondrial DNAs present in a male sterile line of maize, possess terminally attached proteins.

S1 and S2 are short linear mitochondrial DNA molecules found in a particular male sterile cytoplasm of maize. We show here that these DNA molecules and two other related linear DNA species found in maize mitochondria, have proteins attached, probably covalently, to their 5' ends. This is the first demonstration of such a linear DNA-terminal protein association in higher eukaryotes. Such proteins may be involved in priming replication of these DNAs.