Format

Send to

Choose Destination
See comment in PubMed Commons below
Curr Opin Microbiol. 2001 Apr;4(2):132-7.

The AraC transcriptional activators.

Author information

1
Laboratory of Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0560, USA. rgmartin@helix.nih.gov

Abstract

The AraC family of bacterial transcriptional activators regulate diverse genetic systems. Recent X-ray diffraction studies show that the monomeric MarA and Rob activators bind to their asymmetric degenerate DNA sites via two different helix-turn-helix elements. Activation by MarA, SoxS or Rob requires a particular orientation of the asymmetric binding sequence (and hence the activator), depending on its distance from the -10 RNAP signal. Genetic studies are beginning to clarify how the activators interact with RNAP. Growing evidence suggests that for the sugar metabolism activators, multiple binding sites upstream of the promoter anchor the activator in a repressing or nonactivating configuration. By interaction with the sugar and/or CRP, the activator is allosterically altered so it can bind a new set of sites that enable it to activate the promoter. Surprisingly, the virulence activator, Rns, must bind to both upstream and downstream sites in order to activate the rns promoter.

PMID:
11282467
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Support Center