PDBsum entry 3edc

Transcription

PDB id: 3edc

Contents

Protein chains

300 a.a. *

Ligands

HEZ ×4

Waters ×553

* Residue conservation analysis

PDB id:

3edc

Name:

Transcription

Title:

Crystal structure of a 1.6-hexanediol bound tetrameric form of escherichia coli lac-repressor refined to 2.1 resolution

Structure:

Lactose operon repressor. Chain: a, b, c, d. Engineered: yes

Source:

Escherichia coli k12. Organism_taxid: 83333. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.10Å R-factor: 0.159 R-free: 0.201

Authors:

K.A.E.Stenberg

Key ref:

K.A.Stenberg and M.Vihinen (2008). Crystal structure of a 1.6-hexanediol bound tetrameric form of Escherichia coli Lac-repressor refined to 2.1 A resolution. Proteins, 75, 748-759. PubMed id: 19004002 DOI: 10.1002/prot.22284

Date:

03-Sep-08 Release date: 25-Nov-08

Protein chains

P03023  (LACI_ECOLI) -  Lactose operon repressor from Escherichia coli (strain K12)

Seq: 360 a.a.

Struc: 300 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1002/prot.22284

Proteins 75:748-759 (2008)

PubMed id: 19004002

Crystal structure of a 1.6-hexanediol bound tetrameric form of Escherichia coli Lac-repressor refined to 2.1 A resolution.

K.A.Stenberg, M.Vihinen.

ABSTRACT

We report the structure of a novel tetrameric form of the lactose repressor (LacI) protein from Escherichia coli refined to 2.1 A resolution. The tetramer is bound to 1.6-hexanediol present in the crystallization solution and the final R(free) for the structure is 0.201. The structure confirms previously reported structures on the monomer level. However, the tetramer is much more densely packed. This adds a new level of complexity to the interpretation of mutational effects and challenges details in the current model for LacI function. Several amino acids, previously associated with changes in function but unexplained at the structural level, appear in a new structural context in this tetramer which provides new implications for their function. Proteins 2009. (c) 2008 Wiley-Liss, Inc.

Selected figure(s)

Figure 1.
Figure 1. Comparison of the overall protein part of LacI tetramer structures from an identical viewpoint with respect to monomer A (green). The dimer-dimer interface and distances between monomers vary strongly due to the rotation of the CD-dimer. (a) our model, (b) IPTG and ethyl mercury-bound (PDB code 1TLF), (c) apoform (1LBI), (d) IPTG-bound (1LBH) and (e) DNA-bound (1LBG). The distances between the C -atoms of B102 and D102 (in ångströms) are indicated.

Figure 2.
Figure 2. Structure of the closed tetramer. (a) Surface of the complete tetramer. The viewpoint is identical to that of Figure 1(a), green, monomer A; red, monomer B; magenta, monomer C; yellow, monomer D. It is quite evident that the V-cleft is completely closed. (b) Stereo view of the top of the closed dimer-dimer interface. (c) Stereo view of the amino acids at the bottom of the Vcleft between monomers B and D. The KRK-motif of monomer D and some interaction distances are shown under a surface representation. (d) The structure and electron density around Hez-A. The density is from a CNS composite omit map[36], contoured at 1.25 , carve = 1.6 Å.

The above figures are reprinted by permission from John Wiley & Sons, Inc.: Proteins (2008, 75, 748-759) copyright 2008.

Figures were selected by an automated process.