PDBsum entry: 1f39

Viral protein

PDB id: 1f39

Contents

Protein chains

101 a.a. *

Waters ×119

* Residue conservation analysis

PDB id:

1f39

Name:

Viral protein

Title:

Crystal structure of the lambda repressor c-terminal domain

Structure:

Repressor protein ci. Chain: a, b. Fragment: c-terminal domain. Engineered: yes

Source:

Enterobacteria phage lambda. Organism_taxid: 10710. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Nonamer (from PDB file)

Resolution:

1.90Å R-factor: 0.228 R-free: 0.257

Authors:

C.E.Bell,P.Frescura,A.Hochschild,M.Lewis

Key ref:

C.E.Bell et al. (2000). Crystal structure of the lambda repressor C-terminal domain provides a model for cooperative operator binding. Cell, 101, 801-811. PubMed id: 10892750 DOI: 10.1016/S0092-8674(00)80891-0

Date:

01-Jun-00 Release date: 26-Jul-00

Protein chains

P03034  (RPC1_LAMBD) -  Repressor protein CI

Seq: 237 a.a.

Struc: 101 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1016/S0092-8674(00)80891-0

Cell 101:801-811 (2000)

PubMed id: 10892750

Crystal structure of the lambda repressor C-terminal domain provides a model for cooperative operator binding.

C.E.Bell, P.Frescura, A.Hochschild, M.Lewis.

ABSTRACT

Interactions between transcription factors bound to separate operator sites commonly play an important role in gene regulation by mediating cooperative binding to the DNA. However, few detailed structural models for understanding the molecular basis of such cooperativity are available. The c1 repressor of bacteriophage lambda is a classic example of a protein that binds to its operator sites cooperatively. The C-terminal domain of the repressor mediates dimerization as well as a dimer-dimer interaction that results in the cooperative binding of two repressor dimers to adjacent operator sites. Here, we present the x-ray crystal structure of the lambda repressor C-terminal domain determined by multiwavelength anomalous diffraction. Remarkably, the interactions that mediate cooperativity are captured in the crystal, where two dimers associate about a 2-fold axis of symmetry. Based on the structure and previous genetic and biochemical data, we present a model for the cooperative binding of two lambda repressor dimers at adjacent operator sites.

Selected figure(s)

Figure 1.
Figure 1. Structure of the λ Repressor C-Terminal Domain DimerThe dimer in the asymmetric unit of the crystal is shown in ribbon representation. The view is perpendicular to the 2-fold axis of symmetry (noncrystallographic). The monomer on the left (gold) is shown with β strands labeled β1-β7, coil and turn regions L1-L6, and the 3[10]-helix 3[10]. Lys-192 and Ser-149, shown in blue ball-and-stick, form the active site for RecA-mediated cleavage. Residues shown in brown ball-and-stick (and labeled for the green subunit) are affected by mutations that inhibit dimerization. Notice that these residues map to the dimer interface. Also notice that the C-terminal 3[10]-helices are “swapped.”

Figure 2.
Figure 2. Residues of the λ Repressor C-Terminal Domain Involved in RecA-Mediated Cleavage(A) Close-up view of the active site for RecA-mediated cleavage. The orientation is approximately the same as in Figure 1. The final 1.9 Å electron density map (2F[o]-F[c]) is superimposed on the structure and contoured at 1σ. Water molecules are shown as red spheres and hydrogen bonds as dotted lines. By deprotonation, Lys-192 is thought to activate Ser-149 for nucleophilic attack on the carbonyl carbon atom of the Ala-111-Gly-112 peptide bond (not present).(B) A surface representation of the CTD dimer shows residues implicated in the RecA-mediated cleavage. The orientation is the same as in Figure 1. The active-site residues Ser-149 and Lys-192 are shown in cyan. Residues that are affected by ind^− mutations (defective in the RecA-mediated cleavage) are shown in purple. Notice that Phe-189 and Leu-143 form an exposed hydrophobic patch that could be a RecA binding site.

The above figures are reprinted by permission from Cell Press: Cell (2000, 101, 801-811) copyright 2000.

Figures were selected by an automated process.