Molecular Mechanisms of Transcription Initiation at gal Promoters and their Multi-Level Regulation by GalR, CRP and DNA Loop

Biomolecules

Dale E.A. Lewis¹  Sankar Adhya²  Sivaramesh Wigneshweraraj² 

[1] Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4255, USA; E-Mail

关键词: activation;    repression;    DNA looping;    transcription;    galactose operon;   

DOI  :  10.3390/biom5042782

来源: mdpi

【 摘 要 】

Studying the regulation of transcription of the gal operon that encodes the amphibolic pathway of d-galactose metabolism in Escherichia coli discerned a plethora of principles that operate in prokaryotic gene regulatory processes. In this chapter, we have reviewed some of the more recent findings in gal that continues to reveal unexpected but important mechanistic details. Since the operon is transcribed from two overlapping promoters, P1 and P2, regulated by common regulatory factors, each genetic or biochemical experiment allowed simultaneous discernment of two promoters. Recent studies range from genetic, biochemical through biophysical experiments providing explanations at physiological, mechanistic and single molecule levels. The salient observations highlighted here are: the axiom of determining transcription start points, discovery of a new promoter element different from the known ones that influences promoter strength, occurrence of an intrinsic DNA sequence element that overrides the transcription elongation pause created by a DNA-bound protein roadblock, first observation of a DNA loop and determination its trajectory, and piggybacking proteins and delivering to their DNA target.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.