PDBsum entry 3k1r

Structural protein

PDB id: 3k1r

Contents

Protein chains

192 a.a. *

74 a.a. *

Waters ×239

* Residue conservation analysis

PDB id:

3k1r

Name:

Structural protein

Title:

Structure of harmonin npdz1 in complex with the sam-pbm of sans

Structure:

Harmonin. Chain: a. Fragment: npdz1 domain, residues 1-192. Synonym: harmonin scaffold protein, 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. Mutation: yes. Usher syndrome type-1g protein.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: ush1c. Expressed in: escherichia coli. Expression_system_taxid: 511693. Gene: ush1g.

Resolution:

2.30Å R-factor: 0.213 R-free: 0.256

Authors:

L.Pan,J.Yan,M.Zhang

Key ref:

J.Yan et al. (2010). The structure of the harmonin/sans complex reveals an unexpected interaction mode of the two Usher syndrome proteins. Proc Natl Acad Sci U S A, 107, 4040-4045. PubMed id: 20142502 DOI: 10.1073/pnas.0911385107

Date:

28-Sep-09 Release date: 26-Jan-10

Protein chain

Q9Y6N9  (USH1C_HUMAN) -  Harmonin from Homo sapiens

Seq: 552 a.a.

Struc: 192 a.a.*

Protein chain

Q495M9  (USH1G_HUMAN) -  pre-mRNA splicing regulator USH1G from Homo sapiens

Seq: 461 a.a.

Struc: 74 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

DOI no: 10.1073/pnas.0911385107

Proc Natl Acad Sci U S A 107:4040-4045 (2010)

PubMed id: 20142502

The structure of the harmonin/sans complex reveals an unexpected interaction mode of the two Usher syndrome proteins.

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

ABSTRACT

The hereditary hearing-vision loss disease, Usher syndrome I (USH1), is caused by defects in several proteins that can interact with each other in vitro. Defects in USH1 proteins are thought to be responsible for the developmental and functional impairments of sensory cells in the retina and inner ear. Harmonin/USH1C and Sans/USH1G are two of the USH1 proteins that interact with each other. Harmonin also binds to other USH1 proteins such as cadherin 23 (CDH23) and protocadherin 15 (PCDH15). However, the molecular basis governing the harmonin and Sans interaction is largely unknown. Here, we report an unexpected assembly mode between harmonin and Sans. We demonstrate that the N-terminal domain and the first PDZ domain of harmonin are tethered by a small-domain C-terminal to PDZ1 to form a structural and functional supramodule responsible for binding to Sans. We discover that the SAM domain of Sans, specifically, binds to the PDZ domain of harmonin, revealing previously unknown interaction modes for both PDZ and SAM domains. We further show that the synergistic PDZ1/SAM and PDZ1/carboxyl PDZ binding-motif interactions, between harmonin and Sans, lock the two scaffold proteins into a highly stable complex. Mutations in harmonin and Sans found in USH1 patients are shown to destabilize the complex formation of the two proteins.

Selected figure(s)

Figure 1.
The multi-dentate interaction between harmonin and Sans. (A) A schematic diagram showing the domain organizations of harmonin and Sans. The NPDZ1 and SAM-PBM boundaries used in this study are indicated. (B) GST-fusion protein-based pull-down assay showing that NPDZ1 binds to the SAM domain alone and the SAM-PBM of Sans. No interaction between the N-domain and the SAM domain was detected. (C) Analytical gel-filtration analysis showing that harmonin NPDZ1 and Sans SAM-PBM forms a 1∶1 stoichiometric complex. (D) ITC-based measurements of the binding affinities of NPDZ1 with Sans PBM, SAM, and SAM-PBM.

Figure 4.
Molecular details of the harmonin NPDZ1 and Sans SAM-PBM interaction. (A and B) The combined surface charge representation (NPDZ1) and the stick-ribbon model (SAM-PBM) showing the interaction interface between harmonin NPDZ1 and Sans SAM-PBM. The binding interface between the NPDZ1 and Sans PBM is better viewed in (A), whereas the binding interface between the NPDZ1 and Sans SAM is optimally depicted in (B). (C and D) Stereo views showing the detailed interactions between harmonin PDZ1 and Sans PBM (C), and between PDZ1 and Sans SAM (D). The hydrogen bonds and salt bridges involved in the interfaces are indicated as Dashed Lines. (E) A schematic cartoon diagram summarizing the three different binding modes of PDZ domains.

Figures were selected by an automated process.