View source for 1tlf


==UNPRECEDENTED QUATERNARY STRUCTURE OF E. COLI LAC REPRESSOR CORE TETRAMER: IMPLICATIONS FOR DNA LOOPING==
<StructureSection load='1tlf' size='340' side='right'caption='[[1tlf]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1tlf]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/"bacillus_coli"_migula_1895 "bacillus coli" migula 1895]. The March 2003 RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month] feature on ''lac Repressor''  by David S. Goodsell is [http://dx.doi.org/10.2210/rcsb_pdb/mom_2003_3 10.2210/rcsb_pdb/mom_2003_3]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TLF OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1TLF FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=EMC:ETHYL+MERCURY+ION'>EMC</scene>, <scene name='pdbligand=IPT:ISOPROPYL-1-BETA-D-THIOGALACTOSIDE'>IPT</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1tlf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1tlf OCA], [http://pdbe.org/1tlf PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1tlf RCSB], [http://www.ebi.ac.uk/pdbsum/1tlf PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1tlf ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/LACI_ECOLI LACI_ECOLI]] Repressor of the lactose operon. Binds allolactose as an inducer. 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/tl/1tlf_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1tlf ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The crystal structure of the tryptic core fragment of the lac repressor of Escherichia coli (LacR) complexed with the inducer isopropyl-beta-D-thiogalactoside was determined at 2.6 A resolution. The quaternary structure consists of two dyad-symmetric dimers that are nearly parallel to each other. This structure places all four DNA binding domains of intact LacR on the same side of the tetramer, and results in a deep, V-shaped cleft between the two dimers. Each monomer contributes a carboxyl-terminal helix to an antiparallel four-helix bundle that functions as a tetramerization domain. Some of the side chains whose mutation reduce DNA binding form clusters on a surface near the amino terminus. Placing the structure of the DNA binding domain complexed with operator previously determined by nuclear magnetic resonance onto this surface results in two operators being adjacent and nearly parallel to each other. Structural considerations suggest that the two dimers of LacR may flexibly alter their relative orientation in order to bind to the known varied spacings between two operators.

Crystal structure of lac repressor core tetramer and its implications for DNA looping.,Friedman AM, Fischmann TO, Steitz TA Science. 1995 Jun 23;268(5218):1721-7. PMID:7792597<ref>PMID:7792597</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 1tlf" style="background-color:#fffaf0;"></div>

==See Also==
*[[Lac repressor|Lac repressor]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Bacillus coli migula 1895]]
[[Category: Large Structures]]
[[Category: RCSB PDB Molecule of the Month]]
[[Category: Lac Repressor]]
[[Category: Fischmann, T O]]
[[Category: Friedman, A M]]
[[Category: Steitz, T A]]
[[Category: Transcription regulation]]