Met repressor sandbox (Beasley): Difference between revisions

The met operators in ''E. coli'' consist of tandem repeats of eight base pair sequences, AGACGTCT, known as 'met boxes'. <ref name="Phillips,S" /> These met boxes vary in length from 16-40 base pairs, corresponding to two to five met boxes. The consensus sequence is highly symmetrical, with centers of inverted repeats at the center of each met box and at the junctions between them. The <scene name='Met_repressor_(Beasley)/19bp_dna/1'>self complementary 19-base oligonucleotide</scene>, that the met repressor binds to in the E. coli met repressor-operator complex at the top of the page, has the sequence 5'-TTAGACGTCTAGACGTCTA-3' which contains two tandem consensus met boxes flanked by TA base pairs on the 3' end and one unpaired T on the 5' end.<ref name="Phillips">PMID 1406951</ref> One of the products of the methionine biosynthetic pathway is <scene name='Met_repressor_(Beasley)/Sam_ball_and_stick/1'>S-adenosylmethionine (SAM) </scene> and it acts as a corepressor. The repressor has to bind two molecules of SAM non-cooperatively in order for the repressor to bind DNA. The SAM binding does not significantly change the structure of the protein, but it greatly increases the affinity for the operator. <ref name="Phillips,S" /> The following image represents SAM: