Kinetic enhancement of NF-kappaBxDNA dissociation by IkappaBalpha.
A hallmark of the NF-kappaB transcription response to inflammatory cytokines is the remarkably rapid rate of robust activation and subsequent signal repression. Although the rapidity of postinduction repression is explained partly by the fact that the gene for IkappaBalpha is strongly induced by NF-kappaB, the newly synthesized IkappaBalpha still must enter the nucleus and compete for binding to NF-kappaB with the very large number of kappaB sites in the DNA. We present results from real-time binding kinetic experiments, demonstrating that IkappaBalpha increases the dissociation rate of NF-kappaB from the DNA in a highly efficient kinetic process. Analysis of various IkappaB mutant proteins shows that this process requires the C-terminal PEST sequence and the weakly folded fifth and sixth ankyrin repeats of IkappaBalpha. Mutational stabilization of these repeats reduces the efficiency with which IkappaBalpha enhances the dissociation rate.
Bergqvist
Simon
S
Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093-0378, USA.
Alverdi
Vera
V
Mengel
Benedicte
B
Hoffmann
Alexander
A
Ghosh
Gourisankar
G
Komives
Elizabeth A
EA
D000595:Amino Acid Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D006801:Humans; D020672:I-kappa B Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000737:chemistry / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017510:Protein Folding; D017433:Protein Structure, Secondary; D020449:Repetitive Sequences, Amino Acid; D017384:Sequence Deletion
D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D000072000:NF-KappaB Inhibitor alpha; D004247:DNA