1tlf

UNPRECEDENTED QUATERNARY STRUCTURE OF E. COLI LAC REPRESSOR CORE TETRAMER: IMPLICATIONS FOR DNA LOOPING

spinqualitylabelsall models 1tlf, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1tlf is a 4 chain structure with sequence from Escherichia coli. The March 2003 RCSB PDB Molecule of the Month feature on lac Repressor by David S. Goodsell is 10.2210/rcsb_pdb/mom_2003_3. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.6Å Ligands: EMC, IPT Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function LACI_ECOLI Repressor of the lactose operon. Binds allolactose as an inducer. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Lac repressor

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