Transcription termination factor rho of Escherichia coli K-12: some regulatory aspects of its expression and activity.

A highly sensitive radioimmunological assay of the transcription termination factor (rho) of Escherichia coli K-12 has been developed. This method allows to measure in crude bacterial extracts quantities as low as 1.8 X 10(-15) moles of rho. We studied, under various conditions of growth and in mutants lacking or overproducing the cyclic AMP receptor protein (CAP) or adenylate cyclase, the relationship between the level of rho and its poly(C)-dependent ATPase activity. We showed that neither growth conditions, nor the presence or absence of a functional cAMP-CAP complex affect the synthesis and the enzymatic activity of the rho protein.