2lsr
Solution structure of harmonin N terminal domain in complex with a exon68 encoded peptide of cadherin23Solution structure of harmonin N terminal domain in complex with a exon68 encoded peptide of cadherin23
Structural highlights
DiseaseUSH1C_HUMAN Defects in USH1C are the cause of Usher syndrome type 1C (USH1C) [MIM:276904; also known as Usher syndrome type I Acadian variety. USH is a genetically heterogeneous condition characterized by the association of retinitis pigmentosa and sensorineural deafness. Age at onset and differences in auditory and vestibular function distinguish Usher syndrome type 1 (USH1), Usher syndrome type 2 (USH2) and Usher syndrome type 3 (USH3). USH1 is characterized by profound congenital sensorineural deafness, absent vestibular function and prepubertal onset of progressive retinitis pigmentosa leading to blindness.[1] Defects in USH1C are the cause of deafness, autosomal recessive, 18A (DFNB18A) [MIM:602092. A form of sensorineural hearing loss. Sensorineural deafness results from damage to the neural receptors of the inner ear, the nerve pathways to the brain, or the area of the brain that receives sound information.[2] FunctionUSH1C_HUMAN Required for normal development and maintenance of cochlear hair cell bundles. Anchoring/scaffolding protein that is a part of the functional network formed by USH1C, USH1G, CDH23 and MYO7A that mediates mechanotransduction in cochlear hair cells. Required for normal hearing (By similarity). Publication Abstract from PubMedStereocilia tip links of inner ear hair cells are subjected to constant stretching during hair-bundle deflection, and accordingly are well designed to prevent from being broken by mechanical tensions. The roots of tip links, which couple tip links with the cytoskeleton, supposedly play important roles in withstanding large forces under stimulated conditions. The upper root of the tip link is mainly formed by the cytoplasmic tail of cadherin23 and its actin-anchoring protein harmonin. However, the detailed organization mode of the two proteins that gives rise to a strong upper root remains unclear. Here we show that the exon68-encoded peptide of cadherin23 can either interact with the N-terminal domain (NTD) of harmonin or form a homodimer. We demonstrate that the three harmonin binding sites of cadherin23, namely the NTD-binding motif, the exon68 peptide, and the C-terminal PDZ binding motif, do not synergize with each other in binding to harmonin, instead they facilitate formation of polymeric cadherin23/harmonin complexes. The exon68 peptide can promote the cadherin23/harmonin polymer formation via either binding to harmonin NTD or self-dimerization. We propose that the polymeric cadherin23/harmonin complex formed beneath the upper tip link membranes may serve as part of the stable rootlet structure for anchoring the tip links of stereocilia. Large protein assemblies formed by multivalent interactions between cadherin23 and harmonin suggest a stable anchorage structure at the tip link of stereocilia.,Wu L, Pan L, Zhang C, Zhang M J Biol Chem. 2012 Sep 28;287(40):33460-71. doi: 10.1074/jbc.M112.378505. Epub, 2012 Aug 8. PMID:22879593[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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