PDBsum entry 1zoo

Cell adhesion

PDB id: 1zoo

Contents

Protein chain

183 a.a. *

Metals

_CL ×2

_MG ×2

Waters ×12

* Residue conservation analysis

PDB id:

1zoo

Name:

Cell adhesion

Title:

Cd11a i-domain with bound magnesium ion

Structure:

Leukocyte adhesion glycoprotein. Chain: a, b. Fragment: i-domain fragment of lfa-1. Synonym: lfa-1, cd11a/cd18, alphal beta2 integrin, a-domain. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Cell_line: 293. Gene: pcr product. Expressed in: escherichia coli. Expression_system_taxid: 562. Other_details: the protein was refolded from 7m urea

Biol. unit:

Dimer (from PQS)

Resolution:

3.00Å R-factor: 0.279 R-free: 0.264

Authors:

D.J.Leahy,A.Qu

Key ref:

A.Qu and D.J.Leahy (1996). The role of the divalent cation in the structure of the I domain from the CD11a/CD18 integrin. Structure, 4, 931-942. PubMed id: 8805579 DOI: 10.1016/S0969-2126(96)00100-1

Date:

21-Jun-96 Release date: 07-Dec-96

Protein chains

P20701  (ITAL_HUMAN) -  Integrin alpha-L from Homo sapiens

Seq: 1170 a.a.

Struc: 183 a.a.

DOI no: 10.1016/S0969-2126(96)00100-1

Structure 4:931-942 (1996)

PubMed id: 8805579

The role of the divalent cation in the structure of the I domain from the CD11a/CD18 integrin.

A.Qu, D.J.Leahy.

ABSTRACT

BACKGROUND: The integrin family of cell-surface receptors mediates a wide variety of cell-cell and cell-extracellular matrix interactions. Integrin-ligand interactions are invariably dependent on the presence of divalent cations, and a subset of integrins contain a approximately 200 amino acid inserted (I) domain that is important for ligand binding activity and contains a single divalent cation binding site. Many integrins are believed to respond to stimuli by undergoing a conformational change that increases their affinity for ligand, and there is a clear difference between two crystal structures of the CD11b I domain with different divalent cations (magnesium and manganese) bound. In addition to the different bound cation, a 'ligand mimetic' crystal lattice interaction in the CD11b I domain structure with bound magnesium has led to the interpretation that the different CD11b I domain structures represent different affinity states of I domains. The influence of the bound cation on I domain structure and function remains incompletely understood, however. The crystal structure of the CD11a I domain bound to manganese is known. We therefore set out to determine whether this structure changes when the metal ion is altered or removed. RESULTS: We report here the crystal structures of the CD11a I domain determined in the absence of bound metal ion and with bound magnesium ion. No major structural rearrangements are observed in the metal-binding site of the CD11a I domain in the absence or presence of bound manganese ion. The structures of the CD11a I domain with magnesium or manganese bound are extremely similar. CONCLUSIONS: The conformation of the CD11a I domain is not altered by changes in metal ion binding. The cation-dependence of ligand binding thus indicates that the metal ion is either involved in direct interaction with ligand or required to promote a favorable quaternary arrangement of the integrin.

Selected figure(s)

Figure 2.
Figure 2. The overall fold of the CD11a I domain. (a) Ribbon diagram of CD11a-I(EDTA). The side chains of Ser139, Ser141, and Asp239 are shown in green with red oxygen atoms. The N and C termini, the β strands, and the α helical segments are labeled. (b) Stereo view of superimposed Cα backbones of CD11a-I(EDTA) (solid blue line) and CD11a-I(Mn) (dashed red line). The N and C termini are labeled and every tenth residue of CD11a-I(EDTA) is indicated by a solid circle. Figure 2. The overall fold of the CD11a I domain. (a) Ribbon diagram of CD11a-I(EDTA). The side chains of Ser139, Ser141, and Asp239 are shown in green with red oxygen atoms. The N and C termini, the β strands, and the α helical segments are labeled. (b) Stereo view of superimposed Cα backbones of CD11a-I(EDTA) (solid blue line) and CD11a-I(Mn) (dashed red line). The N and C termini are labeled and every tenth residue of CD11a-I(EDTA) is indicated by a solid circle. (Figure made with the program MOLSCRIPT [[4]41].)

Figure 5.
Figure 5. The position of the α7 helices. (a) Deviation of the α7 helices of CD11a-I(EDTA) and CD11a-I(Mn) following superposition. A superposition of Cα backbone traces of CD11a-I(EDTA) and CD11a-I(Mn) is shown. The α7 helix of CD11a-I(EDTA) is shown in blue, and the α7 helix of CD11a-I(Mn) is shown in red. (b) Dimer interaction observed in CD11a-I(Mn) and CD11a-I(Mg) crystal structures. The structures shown constitute the contents of one asymmetric unit. The α7 helices of each molecule are labeled. In both figures the manganese ions are depicted as magenta spheres. Figure 5. The position of the α7 helices. (a) Deviation of the α7 helices of CD11a-I(EDTA) and CD11a-I(Mn) following superposition. A superposition of Cα backbone traces of CD11a-I(EDTA) and CD11a-I(Mn) is shown. The α7 helix of CD11a-I(EDTA) is shown in blue, and the α7 helix of CD11a-I(Mn) is shown in red. (b) Dimer interaction observed in CD11a-I(Mn) and CD11a-I(Mg) crystal structures. The structures shown constitute the contents of one asymmetric unit. The α7 helices of each molecule are labeled. In both figures the manganese ions are depicted as magenta spheres. (Figures made with the program SETOR [[3]43].)

The above figures are reprinted by permission from Cell Press: Structure (1996, 4, 931-942) copyright 1996.

Figures were selected by an automated process.