1TLF

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


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Work: 0.222 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal structure of lac repressor core tetramer and its implications for DNA looping.

Friedman, A.M.Fischmann, T.O.Steitz, T.A.

(1995) Science 268: 1721-1727


  • PubMed Abstract: 
  • 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 ...

    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.


    Organizational Affiliation

    Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
LAC REPRESSOR
A, B, C, D
301Escherichia coli (strain K12)Gene Names: lacI
Find proteins for P03023 (Escherichia coli (strain K12))
Go to UniProtKB:  P03023
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
EMC
Query on EMC

Download SDF File 
Download CCD File 
A, B, C, D
ETHYL MERCURY ION
C2 H5 Hg
MJOUBOKSWBMNGQ-UHFFFAOYSA-N
 Ligand Interaction
IPT
Query on IPT

Download SDF File 
Download CCD File 
A, B, C, D
ISOPROPYL-1-BETA-D-THIOGALACTOSIDE
1-(ISOPROPYLTHIO)-BETA-GALACTOPYRANSIDE
C9 H18 O5 S
BPHPUYQFMNQIOC-NXRLNHOXSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Work: 0.222 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 90.160α = 90.00
b = 64.730β = 91.75
c = 117.940γ = 90.00
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORphasing
X-PLORrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1995-07-31
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance