Structure-Function Aspects of Membrane Associated Prokaryotic DNA Replication

摘要

Membrane associated DNA replication in prokaryotes has been studied intensivelyusing two model systems, Bacillus subtilis and plasmid RK2 cultured in its Escherichia coli host. In the former a new membrane protein that had previously been found to act as an inhibitor of DNA replication was identified (by gene cloning procedures) to be an enzyme of the pyruvate dehydrogenase complex, the E2 subunit dihydrolipoamide acetyl transferase. The identification of this inhibitor is representative of an increasingly recognized phenomenon, namely the existence of multifunctional proteins. The temporal expression of the protein during the growth cycle has also been elucidated. Its action appears to be controlled by proteases which degrade the protein prior to a round of DNA replication. In the latter, plasmid DNA replication has been found to be associated with the inner but not outer membrane of its E. coli host, while plasmid encoded initiation proteins have been found to be associated with both membrane fractions. Although sequence analysis of the genes encoding the proteins predict them to be peripheral (loosely associated) membrane proteins, they can not be dissociated by treatments designed to remove such peripheral proteins, suggesting that part of this association is integral in nature (strongly associated). Membrane associated DNA replication, Repressor protein, Initiation protein, Protein-membrane association.