A Promoter Overlapping with that of nodF is Responsible for a New RNA Molecule Transcription in Rhizobium leguminosarum.

ABSTRACT

The expression of nod genes of rhizobia is controlled at the transcriptional level in a complicated way. In this work, a new promoter, which is responsible for an RNA molecule transcription in the opposite direction to that of nodF, was identified in Rhizobium leguminosarum. This new promoter was characterized to overlap with that of nodF, and the size of px(2), the RNA molecule initiated from this promoter was determined to be of approximately 0.72 kb in length. The study on px2 showed that its transcription depended on the Escherichia coli sigma(70)- like factor of Rhizobium leguminosarum, and that the in vitro transcription of px(2) was inhibited by Px, a newly identified regulatory protein in our lab. The involvement of px(2) in the regulation of nod gene expression is suggested.