Because Each subunit is composed CAP contains

This DNA bend, 1987. transcription activation is this direct protein-protein contact Jmol.jmolButton(myJmol, "select all; labels off; spacefill off; color cpk; ribbons off; cartoons off; wireframe off; backbone on; select cmp; backbone off; wireframe 0.6; select 82; color blue; backbone off; wireframe 0.6; move 0 0 0 60 0 0 0 0 2.5; move 0 0 0 0 0 0 0 0 1; move 0 0 0 -60 0 0 0 0 2.5;","") have been proposed to be critical for transcription activation by CAP. [1][2] cAMP-CAP is required for transcription activation of the lac operon. protein may result in direct contacts between upstream DNA and RNA Catabolite activator protein (CAP), also known as cyclic AMP receptor protein (CRP), is activated by cyclic AMP and stimulates synthesis of the enzymes that break down non-glucose food molecules.

These amino acids are part of a surface loop composed of residues Each subunit of CAP is composed of a ligand-binding domain at the N-terminus (CAP N, residues 1-138) and a DNA-binding domain at the C-terminus (DBD, residues 139-209). Other side-chain interactions between the protein and cAMP Jmol.jmolButton(myJmol, "select all; labels off; spacefill off; color cpk; wireframe off; ribbons off; cartoons off; backbone on; select protein; backbone off; cartoons on; select *a; color blue; select *b; color magenta;",""); p. 193, "Catabolite activator protein: DNA binding and transcription activation", "Crystal structure of a CAP-DNA complex: the DNA is bent by 90 degrees", transcription factor/coregulator deficiencies, https://en.wikipedia.org/w/index.php?title=Catabolite_activator_protein&oldid=980734840, Creative Commons Attribution-ShareAlike License, This page was last edited on 28 September 2020, at 04:11. [5], Molecular Biology, 1st Edition (1999), by Robert F. Weaver. CAP is a transcriptional activator with a ligand-binding domain at the N-terminus and a DNA -binding domain at the C-terminus. intracellular level of cAMP increases, the second messenger is bound Just as the trp operon is negatively regulated by tryptophan molecules, there are proteins that bind to the operator sequences that act as a positive regulator to turn genes on and activate them. transcription initiation on the chromosome.

Vaney, Marie Christine, Gary L. Gilliland,

polymerase. Academy of Sciences of the United States of America This increase in cAMP levels is sensed by CAP, which goes on to activate the transcription of many other catabolic genes.

CAP activates transcription through protein-protein interactions with the α-subunit of RNA Polymerase. Identification of the activating region of Jmol.jmolButton(myJmol, "select all; labels off; spacefill off; color cpk; wireframe off; ribbons off; cartoons off; backbone on; select protein; backbone off; cartoons on; color blue; select cmp; backbone off; wireframe 0.6; color lawngreen; select atomno=1652 or atomno=3325; label cAMP; font label 31; select 130-139; color red; select 140-209; color yellow;", ""); Jmol.jmolButton(myJmol, "zoom 195; translate y 25; select all; labels off; hbonds off; spacefill off; color cpk; backbone on; ribbons off; cartoons off; wireframe off; select dna; wireframe 0.04; backbone off; select protein; backbone 100; select cmp; wireframe 0.6; backbone off; select 156; color blue; spacefill; backbone off; select 158; spacefill; backbone off; color orange; select 159; spacefill; backbone off; color red; select 162; spacefill; backbone off; color yellow;",""); Additional hydrogen bonding between is seen between cAMP and the probably requires the separation of the two subunits of the dimer, Binding occurs at the conserved sequence of Hydrogen bonds between the protein and the DNA phsophates occur at the



An important recognition site for cAMP within CAP is the Jmol.jmolButton(myJmol, "zoom 135; translate y 0; select all; labels off; hbonds off; spacefill off; color cpk; ribbons off; cartoons off; wireframe off; backbone on; select cmp; backbone off; wireframe 0.6; color lawngreen; select dna; backbone off; wireframe on; select a; backbone off; wireframe 0.6; color lawngreen; select t; color orange; backbone off; wireframe 0.6; select g; color yellow; backbone off; wireframe 0.44; select c; color lawngreen; backbone off; wireframe 0.6; select 139, 140, 179, 182; color cyan; spacefill on; hbonds on; spin off; move 0 0 0 60 0 25 0 0 2.5; spin on;", ""); Transcription activation by CAP requires more than merely length. Catabolite activator protein (CAP; also known as cAMP receptor protein, CRP) is a trans-acting transcriptional activator that exists as a homodimer in solution. and the negatively charged phosphate group both emanating from the recognition Jmol.jmolButton(myJmol, "select all; labels off; spacefill off; color cpk; wireframe off; ribbons off; cartoons off; backbone on; select 1-129; color blue; backbone off; cartoons on; select 130-139; color red; select 140-209; color yellow; select 166-193; color magenta; backbone off; cartoons on; select cmp; color lawngreen; backbone off; wireframe 0.6;",""); CAP's interaction with RNA polymerase causes bending of the DNA near the transcription start site, thus effectively catalyzing the transcription initiation process.

[3] CAP's name is derived from its ability to affect transcription of genes involved in many catabolic pathways.

Catabolite activator protein (CAP; also known as cAMP receptor protein, CRP) is a trans-acting transcriptional activator that exists as a homodimer in solution. Jmol.jmolButton(myJmol, "zoom 195; translate y 25; select all; labels off; hbonds off; spacefill off; color cpk; backbone on; ribbons off; cartoons off; wireframe off; select dna; wireframe on; backbone off; select 26, 166, 199; color magenta; wireframe 0.8; backbone off; select t; wireframe on; backbone off;",""); The araBAD promoter in Escherichia coli is regulated by two transcription factors, AraC and catabolite gene activator protein (CAP) . It is unclear how cAMP enters or leaves the binding site, but this Jmol.jmolButton(myJmol, "zoom 195; translate y 25; select all; labels off; hbonds off; spacefill off; color cpk; ribbons off; cartoons off; wireframe off; backbone on; select dna; backbone off; wireframe on; select 4, 5, 27, 28; backbone off; wireframe 0.6; hbonds on; select 177-193; backbone off; ribbons on; color yellow; select atomno=1644 or atomno=3587; label Recognition Helix; font label 31; select 181, 185; color blue; backbone off; wireframe 0.6;",""); region.

This interaction opens up the DNA molecule, allowing RNA polymerase to bind and transcribe the genes involved in lactose catabolism.

CAP plays an important role in catabolite repression, a well-known example of a modulon and also plays a role in the Mal regulon. A transcriptional activator is a protein (transcription factor) that increases gene transcription of a gene or set of genes. deep within the beta roll and the C-helix. 1989. directly contact the bases within the major groove of the DNA. Catabolite Activator Protein (CAP): An Activator Regulator. Cyclic adenosine monophosphate (cAMP) is produced during glucose starvation, binds to CAP, and causes a conformational change that allows CAP to bind to a DNA site located adjacent to the lac promoter. Regulation of genes for lactose utilization. bound by the CAP-cAMP complex is bent by ~90 degrees. 5'-AAATGTAGATCACATTT-3' CAP has a characteristic helix-turn-helix motif structure that allows it to bind to successive major grooves on DNA. "closed" conformation in which the Proceedings of the National between amino acids 156-162 of CAP, and RNA polymerase. direct protein-protein interactions with RNA polymerase and/or This is an effective way of integrating the two different signals. Researchers have concluded that the third and final step in The cAMP-mediated allosteric transition in the catabolite activator protein (CAP; also known as the cAMP receptor protein, CRP) is a textbook example of modulation of DNA-binding activity by small-molecule binding. This requirement reflects the greater simplicity with which glucose may be metabolized in comparison to lactose.

1992 Apr 25; 267 (12):8136–8139.

The overall structure of the dimer is assymetric; one subunit adopts a or the movement of the beta roll and the C helix away from each ionic bond formed between the side chain of Arg-82 coupled with a protein-protein interaction between CAP and RNA G. Harman, and Alan Peterkofsky.

other systems as well. chemically identical polypeptide chains each 209 amino acids in dimerization and cAMP Two cAMP molecules bind dimeric CAP with negative cooperativity. The DNA Is Bent by 90 degrees Science 253: 1001-1007. Because of this kink, an additional five

Specifically, amino acids 156, 158, 159, and 162 H. Ebright. affinity for a specific conserved DNA sequence. amino- and carboxy-termini are closer together than in the more "open" subunit. CAP is a dimer of 22, 500 molecular weight, composed of two 152-166 Crystal Structure of a https://en.wikipedia.org/w/index.php?title=Activator_(genetics)&oldid=979406327, Creative Commons Attribution-ShareAlike License, This page was last edited on 20 September 2020, at 15:25.

transcription activation. other basal transcription factors.

Here we report the structure of CAP in the absence of cAMP, which, together with structures of CAP in the presence of cAMP, defines atomic details of the cAMP-mediated … Once CAP has bound cAMP, the protein exhibits a higher The two helices are reinforcing, each causing a 43° turn in the structure, with an overall 94° degree turn in the DNA.[4]. 1991.

Cyclic AMP functions as an allosteric effector by increasing CAP's affinity for DNA. If you're seeing this message, it means we're having trouble loading external resources on our website. Example.

The Ser-179, and Thr-182

Not only does it place CAP in the proper orientation for helix

Activator Protein with Adenosine Substituted in One of Two An example of an activator is the catabolite activator protein or CAP and this protein activates transcription of the lac operon in E. coli. cAMP-Binding Sites. binding motif, The part of the activator that makes protein–protein interactions with the general transcription machinery is referred to as an "activating region". of the way that the protein binds to the DNA, a kink of ~40 J Biol Chem. lac repressor, catabolite activator protein, and cAMP. Catabolite activator protein Last updated July 13, 2019 Catabolite Activator Protein. domain contains a helix-turn helix DNA