A Promoter Overlapping with that of

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

YANG Yang, HU Hai-Liang, HONG Guo-Fan^*
( Shanghai Institute of Biochemistry, the Chinese Academy of Sciences,
Shanghai 200031, China )

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 px₂, 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 σ⁷⁰–
like factor of Rhizobium leguminosarum, and that the in vitro
transcription of px₂ was inhibited by Px, a newly identified
regulatory protein in our lab. The involvement of px₂ in the
regulation of nod gene expression is suggested. �お�
Key word    promoter；transcription；RNA polymerase；inhibition

^*Corresponding author：Tel，86-21-64374430-221；Fax，86-21-64338357；e-mail，[email protected]