Gene Regulation and Transcriptional Regulation in Bacteria

The catabolite gene activator protein insert ignore into journalissuearticles values(CAP); and the f umurate n itrate r eductase insert ignore into journalissuearticles values(FNR); are two founder members of the growing CRP-FNR protein superfamily. The consensus FNR binding site insert ignore into journalissuearticles values(TTGAT-N 4 -ATCAA); closely resembles that of CRP to the extent that both contain a common core motif insert ignore into journalissuearticles values( N TGA N -N 4 - N TCA N );. The transcription factor FNR plays a role in altering gene expression between aerobic and anaerobic conditions but CRP regulators control the response to glucose starvation. Protein DNA interactions occur between the regulatory protein and DNA at the corresponding promoter using the consensus either CRP or FNR binding sites. Successful transcriptional activation generally requires contact between a DNA-bound activator and RNA polymerase in order to generate on effective complex. CRP promoters are grouped into two classes depending on the location of DNA binding site. Class I promoters contains transcription activator binding sites centered near position -61.5, -71, -82 or -92. Class II promoters the regulator proteins bind to a site centered at or near -41.5 so three possible contacts, α CTD -AR1, α NTD -AR2 and δ 70 -AR3, occur between regulator and RNA polymerase. FNR and FLP act as a class II activator.   Key Words : Transcription regulation, FNR, CAP, FLP .