The epitopes have been localized for a set of monoclonal antibodies specific for the α subunit of the Escherichia coli RNA polymerase. The antibodies are classified into three groups based on their epitopic assignments. Group 1, mAb 123C2, maps in the N terminus of α between amino acids 1 and 23; Group 2 antibodies (mAb 129C4, mAb 124D1 and mAb 121C5) map in the central region between amino acids 190 and 210; Group 3 antibodies (mAb 130B1 and mAb 125C6) map in the C terminus between amino acids 310 and 320. mAb 130C2 is anomalous since it maps to the N terminus between amino acids 1 and 23 as well as to the C terminus between amino acids 320 and 329. The antibodies were used to investigate the role of α in transcription activation with cAMP receptor protein-dependent promoters. Three antibodies (130C2, 121C5, and 125C6) inhibited cAMP receptor protein-dependent initiation with lac P+ but not with lac UV5 or gal P+. Inhibition was observed with free RNA polymerase and the closed promoter complex; the preformed open promoter complex was insensitive. Only lac P+ was sensitive to these anti-α antibodies supporting the concept that the mode of interaction of RNA polymerase with cAMP receptor protein differs between lac P+ and gal P+.
|Number of pages
|Journal of Biological Chemistry
|Published - 1994 Sept 23