PDBsum entry 2kbs

Structural protein/cell adhesion

PDB id: 2kbs

Contents

Protein chain

92 a.a. *

Ligands

THR-PRO-LEU-GLU-ILE-THR-GLU-LEU

* Residue conservation analysis

PDB id:

2kbs

Name:

Structural protein/cell adhesion

Title:

Solution structure of harmonin pdz2 in complex with the carboxyl tail peptide of cadherin23

Structure:

Harmonin. Chain: a. Fragment: pdz2 domain, unp residues 208-299. Synonym: usher syndrome type-1c protein, autoimmune enteropathy- related antigen aie-75, antigen ny-co-38/ny-co-37, pdz-73 protein, renal carcinoma antigen ny-ren-3. Engineered: yes. Octameric peptide from cadherin-23. Chain: b.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: harmonin. Expressed in: escherichia coli. Expression_system_taxid: 469008. Gene: cadherin23.

NMR struc:

20 models

Authors:

L.Pan,J.Yan,L.Wu,M.Zhang

Key ref:

L.Pan et al. (2009). Assembling stable hair cell tip link complex via multidentate interactions between harmonin and cadherin 23. Proc Natl Acad Sci U S A, 106, 5575-5580. PubMed id: 19297620 DOI: 10.1073/pnas.0901819106

Date:

05-Dec-08 Release date: 31-Mar-09

Protein chain

Q9Y6N9  (USH1C_HUMAN) -  Harmonin from Homo sapiens

Seq: 552 a.a.

Struc: 92 a.a.

DOI no: 10.1073/pnas.0901819106

Proc Natl Acad Sci U S A 106:5575-5580 (2009)

PubMed id: 19297620

Assembling stable hair cell tip link complex via multidentate interactions between harmonin and cadherin 23.

L.Pan, J.Yan, L.Wu, M.Zhang.

ABSTRACT

The hereditary hearing-vision loss disease Usher syndrome (USH) is caused by defects in several proteins, most of which form an integrated protein network called Usher interactome. Harmonin/Ush1C is a master scaffold in the assembly of the Usher protein complexes, because harmonin is known to bind to every protein in the Usher interactome. However, the biochemical and structural mechanism governing the Usher protein complex formation is largely unclear. Here, we report that the highly-conserved N-terminal fragment of harmonin (N-domain) immediately preceding its PDZ1 adopts an autonomously-folded domain. We discovered that the N-domain specifically binds to a short internal peptide fragment of the cadherin 23 cytoplasmic domain. The structures of the harmonin N-domain alone and in complex with the cadherin 23 internal peptide fragment uncovered the detailed binding mechanism of this interaction between harmonin and cadherin 23. We further elucidated the harmonin PDZ domain-mediated cadherin 23 binding by solving the structure of the second harmonin PDZ domain in complex with the cadherin 23 carboxyl tail. The multidentate binding mode between harmonin and cadherin 23 provides a structural and biochemical basis for the harmonin-mediated assembly of stable tip link complex in the auditory hair cells.

Selected figure(s)

Figure 1.
Harmonin contains a novel N-terminal domain. (A) Structure-based sequence alignment of the N-domain from the different harmonin family members. In this alignment, the conserved hydrophobic residues are shown in orange, negatively-charged residues are in magenta, positively-charged residues are in blue, and the rest of the highly-conserved residues are in green. The residues that are critical for binding to the cadherin 23 peptide are boxed and highlighted by red stars or triangles. For comparison, the N-terminal region of whirlin from human and mouse are also included. (B) Stereoview of a representative NMR structure of the harmonin N-domain drawn in the ribbon diagram. (C) Surface representation showing the existence of a unique exposed hydrophobic pocket in the N-domain (highlighted by a black circle), which is hypothesized to serve as the binding site for potential target proteins. In this presentation, the hydrophobic amino acid residues are drawn in yellow, the positively-charged residues are blue, the negatively-charged residues are red, and the uncharged polar residues are gray.

Figure 4.
Molecular details of the interaction between the N-domain and the Cad23 peptide. (A) Stereoview showing the detailed interactions of the Cad23 peptide with the residues from the harmonin N-domain. (B) Western blot analysis showing the interactions between cadherin 23 with 2 harmonin N-domain mutants. The figure also shows that the corresponding N-domain from whirlin does not bind to cadherin 23.

Figures were selected by an automated process.