Expression systems and physiological control of promoter activity in bacteria.

Promoter activity in vivo is not just dependent on the performance of the regulator/promoter pair which may predominantly control transcription initiation in response to a given signal, it also relies on overimposed mechanisms that connect the activity of individual promoters to the metabolic and energetic status of the bacterial cells. Such mechanisms - which frequently become limiting for biotechnological applications involving regulated promoters - include classic (i.e. cAMP/CRP-mediated) or alternative catabolite control checks, recruitment of protein intermediates of the phosphotransferase sugar transport system, coregulation through protein-induced DNA bending and the interplay of sigma factors during various growth stages.