Occlusion of RNA Polymerase by Oligomerization of DnaA Protein over the dnaA Promoter of Escherichia coli *  Yong Sun Lee § ¶ and Deog Su Hwang From the Institute for Molecular Biology and Genetics and the § Department of Microbiology , Seoul National University , Seoul 151-742 , Korea DnaA protein , the initiator protein for initiation of Escherichia coli chromosomal replication , has been shown to repress its own expression from two dnaA promoters , 1P and 2P .