1rcs

<StructureSection load='1rcs' size='340' side='right'caption='[[1rcs]], [[NMR_Ensembles_of_Models | 15 NMR models]]' scene=''>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=TRP:TRYPTOPHAN'>TRP</scene></td></tr>

[[https://www.uniprot.org/uniprot/TRPR_ECOLI TRPR_ECOLI]] This protein is an aporepressor. When complexed with L-tryptophan it binds the operator region of the trp operon (5'-ACTAGT-'3') and prevents the initiation of transcription. The complex also regulates trp repressor biosynthesis by binding to its regulatory region.

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== Publication Abstract from PubMed ==

The solution structures of the complex between Escherichia coli trp holorepressor and a 20 base-pair consensus operator DNA were determined. The majority of proton chemical shifts of the trp holorepressor and operator DNA were assigned from homonuclear 2D NOESY spectra of selectively deuterated analog-operator DNA complexes and the 3D NOESY-HMQC spectrum of a uniformly 15N-labeled repressor-operator DNA complex. The structures were calculated using restrained molecular dynamics and sequential simulated annealing with 4086 NOE and other experimental constraints. The root-mean-squared deviation (RMSD) among the calculated structures and their mean is 0.9(+/- 0.3)A for the repressor backbone, 1.1(+/- 0.5)A for the DNA backbone, and 1.3(+/- 0.3)A for all heavy atoms. The DNA is deformed to a significant extent from the standard B DNA structure to fit the helix-turn-helix (HTH) segment of the repressor (helices D and E) into its major grooves. Little change is found in the ABCF core of the repressor on complexation in comparison to the free repressor, but changes in the cofactor L-tryptophan binding pocket and the HTH segment are observed. The N-terminal residues (2 to 17) are found to be disordered and do not form stable interactions with DNA. Direct H-bonding to the bases of the operator DNA is consistent with all of our observed NOE constraints. Hydrogen bonds from NH eta 1 and NH eta 2 of Arg69 to O-6 and N-7 of G2 are compatible with the solution structure, as they are with the crystal structure. Other direct H-bonds from Lys72, Ala80, Ile79, Thr83 and Arg84 to base-pair functional groups can also be formed in our solution structures.

The solution structures of the trp repressor-operator DNA complex.,Zhang H, Zhao D, Revington M, Lee W, Jia X, Arrowsmith C, Jardetzky O J Mol Biol. 1994 May 13;238(4):592-614. PMID:8176748<ref>PMID:8176748</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

<references/>

[[Category: Zhao, D]]

[[Category: Zheng, Z]]

[[Category: Trp]]