Promoter Selectivity of the Bradyrhizobium japonicum RpoH Transcription Factors In Vivo and In Vitro

• DOI: 10.1128/jb.180.9.2395-2401.1998
• Publication Date: 2019-12-31T16:33:01Z
• Authors: Franz Narberhaus; Michael Kowarik; Christoph Beck; Hauke Hennecke
• Keywords: Sigma factor; Transcription

ABSTRACT Expression of the dnaKJ and groESL 1 heat shock operons Bradyrhizobium japonicum depends on a ς 32 -like transcription factor. Three such factors (RpoH , RpoH 2 3 ) have previously been identified in this organism. We report here that they direct from some but not all -type promoters when respective rpoH genes are expressed Escherichia coli . All three were purified as soluble C-terminally histidine-tagged proteins, although bulk overproduced was insoluble. The proteins recognized by an anti- E. serum. While productively interacted with core RNA polymerase produced groE transcript vitro, unable to do so. B. prepared reconstituted proteins. Again, active, initiated at promoters. In cases, vitro start site shown be identical determined vivo. Promoter competition experiments revealed suboptimal for - or -containing mixture different templates, promoter preferred over any other promoter. Differences observed specificities both sigma toward -dependent conclude primary function is supply cell DnaKJ under normal growth conditions whereas responsible mainly increasing level GroESL after shock.