PDBsum entry 2ecs

Transcription

PDB id: 2ecs

Contents

Protein chains

60 a.a. *

Ligands

SO4 ×4

ACT ×4

Metals

_LI ×2

_CL

Waters ×161

* Residue conservation analysis

PDB id:

2ecs

Name:

Transcription

Title:

Lambda cro mutant q27p/a29s/k32q at 1.4 a in space group c2

Structure:

Phage lambda cro. Chain: a, b. Engineered: yes. Mutation: yes

Source:

Enterobacteria phage lambda. Organism_taxid: 10710. Gene: cro. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.40Å R-factor: 0.141 R-free: 0.175

Authors:

B.M.Hall,S.A.Roberts,M.H.Cordes

Key ref:

B.M.Hall et al. (2008). Two structures of a lambda Cro variant highlight dimer flexibility but disfavor major dimer distortions upon specific binding of cognate DNA. J Mol Biol, 375, 802-811. PubMed id: 18054042 DOI: 10.1016/j.jmb.2007.10.082

Date:

14-Feb-07 Release date: 08-Jan-08

Protein chains

P03040  (RCRO_LAMBD) -  Regulatory protein cro from Escherichia phage lambda

Seq: 66 a.a.

Struc: 60 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

DOI no: 10.1016/j.jmb.2007.10.082

J Mol Biol 375:802-811 (2008)

PubMed id: 18054042

Two structures of a lambda Cro variant highlight dimer flexibility but disfavor major dimer distortions upon specific binding of cognate DNA.

B.M.Hall, S.A.Roberts, A.Heroux, M.H.Cordes.

ABSTRACT

Previously reported crystal structures of free and DNA-bound dimers of lambda Cro differ strongly (about 4 A backbone rmsd), suggesting both flexibility of the dimer interface and induced-fit protein structure changes caused by sequence-specific DNA binding. Here, we present two crystal structures, in space groups P3(2)21 and C2 at 1.35 and 1.40 A resolution, respectively, of a variant of lambda Cro with three mutations in its recognition helix (Q27P/A29S/K32Q, or PSQ for short). One dimer structure (P3(2)21; PSQ form 1) resembles the DNA-bound wild-type Cro dimer (1.0 A backbone rmsd), while the other (C2; PSQ form 2) resembles neither unbound (3.6 A) nor bound (2.4 A) wild-type Cro. Both PSQ form 2 and unbound wild-type dimer crystals have a similar interdimer beta-sheet interaction between the beta1 strands at the edges of the dimer. In the former, an infinite, open beta-structure along one crystal axis results, while in the latter, a closed tetrameric barrel is formed. Neither the DNA-bound wild-type structure nor PSQ form 1 contains these interdimer interactions. We propose that beta-sheet superstructures resulting from crystal contact interactions distort Cro dimers from their preferred solution conformation, which actually resembles the DNA-bound structure. These results highlight the remarkable flexibility of lambda Cro but also suggest that sequence-specific DNA binding may not induce large changes in the protein structure.

Selected figure(s)

Figure 1.
Fig. 1. λ Cro dimer structures, including (a) the crystal structure of wild-type Cro with symmetric cognate consensus DNA (PDB ID 6CRO), (b) the crystal structure of free wild-type Cro (5CRO), (c) the solution ensemble of free wild-type Cro (1COP), and (d and e) the two forms of the PSQ Cro variant solved in the present study. This figure was generated using PyMOL (DeLano Scientific, San Carlos, CA).

Figure 5.
Fig. 5. β-Sheet superstructures in the crystal structures of (a) wild-type λ Cro (5CRO) and (b) PSQ form 2. The two views in (a) illustrate the closed 12-stranded tetrametric β-barrel formed by the two dimers in the asymmetric unit of the wild-type λ Cro structure. (b) shows five symmetry-related dimers of PSQ, which illustrate the infinite corkscrew of β-structure along one crystal axis. The picture is oriented so that the leftmost PSQ dimer in (b) may be compared to the wild-type dimer in the foreground of the left half of (a). Each dimer in PSQ form 2 interacts with two other symmetry-related dimers, while in wild-type Cro, each dimer interacts with only one other dimer. Loops at the N- and C-termini of all structures are omitted for clarity. This figure was generated using PyMOL.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2008, 375, 802-811) copyright 2008.

Figures were selected by an automated process.