PDBsum entry 1i92

Signaling protein

PDB id: 1i92

Contents

Protein chain

91 a.a. *

Metals

_CL ×2

Waters ×57

* Residue conservation analysis

PDB id:

1i92

Name:

Signaling protein

Title:

Structural basis of the nherf pdz1-cftr interaction

Structure:

Na+/h+ exchange regulatory co-factor. Chain: a. Fragment: pdz1 domain (residues 11-94). Synonym: nhe-rf. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: nherf. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.70Å R-factor: 0.191 R-free: 0.217

Authors:

S.Karthikeyan,T.Leung,J.A.A.Ladias

Key ref:

S.Karthikeyan et al. (2001). Structural basis of the Na+/H+ exchanger regulatory factor PDZ1 interaction with the carboxyl-terminal region of the cystic fibrosis transmembrane conductance regulator. J Biol Chem, 276, 19683-19686. PubMed id: 11304524 DOI: 10.1074/jbc.C100154200

Date:

16-Mar-01 Release date: 27-Jun-01

Protein chain

O14745  (NHRF1_HUMAN) -  Na(+)/H(+) exchange regulatory cofactor NHE-RF1 from Homo sapiens

Seq: 358 a.a.

Struc: 91 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

DOI no: 10.1074/jbc.C100154200

J Biol Chem 276:19683-19686 (2001)

PubMed id: 11304524

Structural basis of the Na+/H+ exchanger regulatory factor PDZ1 interaction with the carboxyl-terminal region of the cystic fibrosis transmembrane conductance regulator.

S.Karthikeyan, T.Leung, J.A.Ladias.

ABSTRACT

The PDZ1 domain of the Na(+)/H(+) exchanger regulatory factor (NHERF) binds with nanomolar affinity to the carboxyl-terminal sequence QDTRL of the cystic fibrosis transmembrane conductance regulator (CFTR) and plays a central role in the cellular localization and physiological regulation of this chloride channel. The crystal structure of human NHERF PDZ1 bound to the carboxyl-terminal peptide QDTRL has been determined at 1.7-A resolution. The structure reveals the specificity and affinity determinants of the PDZ1-CFTR interaction and provides insights into carboxyl-terminal leucine recognition by class I PDZ domains. The peptide ligand inserts into the PDZ1 binding pocket forming an additional antiparallel beta-strand to the PDZ1 beta-sheet, and an extensive network of hydrogen bonds and hydrophobic interactions stabilize the complex. Remarkably, the guanido group of arginine at position -1 of the CFTR peptide forms two salt bridges and two hydrogen bonds with PDZ1 residues Glu(43) and Asn(22), respectively, providing the structural basis for the contribution of the penultimate amino acid of the peptide ligand to the affinity of the interaction.

Selected figure(s)

Figure 1.
Fig. 1. Structure of the NHERF PDZ1 domain bound to the CFTR sequence QDTRL. A, sequence comparison of PDZ domains that bind to CFTR. The indicated PDZ domains from human NHERF (5), human NHERF2 (8), and murine PDZK1/CAP70 (12) were aligned using MACAW (36). Absolutely conserved residues are shown as white letters on blue background. Identical residues in four domains are shaded in cyan. The secondary structure of NHERF PDZ1 is indicated at the top. Conserved acidic residues proposed to interact with Arg 1 of the CFTR ligand are denoted by an asterisk. B, stereo view of the NHERF PDZ1 crystal packing. Each carboxyl terminus serves as a ligand for a neighboring PDZ1 molecule. C, ribbon diagram of the NHERF PDZ1 domain bound to the QDTRL peptide. The strands 1- 6 are shown in yellow, and the helices 1 and 2 are shown in green. The peptide ligand QDTRL is shown in pink. The figure was made using MOLSCRIPT (37) and Raster3D (38). D, surface topology of the NHERF PDZ1 bound to the peptide QDTRL. The figure was generated using GRASP (39).

Figure 2.
Fig. 2. NHERF PDZ1 interactions with the peptide QDTRL. A, stereo view of a 2F[obs] F[calc] electron density map calculated at 1.7-Å resolution and contoured at 1 at the peptide-binding site. B, stereo image of the NHERF PDZ1 binding pocket bound to the carboxyl-terminal peptide ligand (gray). Carbon, oxygen, and nitrogen atoms are shown in black, red, and blue, respectively. Water molecules are shown as red spheres and hydrogen bonds as dashed lines. C, two-dimensional representation of the interactions observed between the NHERF PDZ1 residues (orange) and the peptide ligand (purple). Dashed lines denote hydrogen bonds, and numbers indicate hydrogen bond lengths in Å. Hydrophobic interactions are shown as arcs with radial spokes. The figure was made using LIGPLOT (40).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2001, 276, 19683-19686) copyright 2001.