7as7 | pdb_00007as7
Crystal structure of the GCD-associated TGFBIp mutant R124H
Structural highlights
DiseaseBGH3_HUMAN Defects in TGFBI are the cause of epithelial basement membrane corneal dystrophy (EBMD) [MIM:121820; also known as Cogan corneal dystrophy or map-dot-fingerprint type corneal dystrophy. EBMD is a bilateral anterior corneal dystrophy characterized by grayish epithelial fingerprint lines, geographic map-like lines, and dots (or microcysts) on slit-lamp examination. Pathologic studies show abnormal, redundant basement membrane and intraepithelial lacunae filled with cellular debris. Although this disorder usually is not considered to be inherited, families with autosomal dominant inheritance have been identified.[1] Defects in TGFBI are the cause of corneal dystrophy Groenouw type 1 (CDGG1) [MIM:121900; also known as corneal dystrophy granular type. Inheritance is autosomal dominant. Corneal dystrophies show progressive opacification of the cornea leading to severe visual handicap.[2] Defects in TGFBI are the cause of corneal dystrophy lattice type 1 (CDL1) [MIM:122200. Inheritance is autosomal dominant. Defects in TGFBI are a cause of corneal dystrophy Thiel-Behnke type (CDTB) [MIM:602082; also known as corneal dystrophy of Bowman layer type 2 (CDB2). Defects in TGFBI are the cause of Reis-Buecklers corneal dystrophy (CDRB) [MIM:608470; also known as corneal dystrophy of Bowman layer type 1 (CDB1).[3] [4] [5] Defects in TGFBI are the cause of lattice corneal dystrophy type 3A (CDL3A) [MIM:608471. CDL3A clinically resembles to lattice corneal dystrophy type 3, but differs in that its age of onset is 70 to 90 years. It has an autosomal dominant inheritance pattern.[6] [7] Defects in TGFBI are the cause of Avellino corneal dystrophy (ACD) [MIM:607541. ACD could be considered a variant of granular dystrophy with a significant amyloidogenic tendency. Inheritance is autosomal dominant. FunctionBGH3_HUMAN Binds to type I, II, and IV collagens. This adhesion protein may play an important role in cell-collagen interactions. In cartilage, may be involved in endochondral bone formation. Publication Abstract from PubMedProtein aggregation in the outermost layers of the cornea, which can lead to cloudy vision and in severe cases blindness, is linked to mutations in the extracellular matrix protein transforming growth factor-beta-induced protein (TGFBIp). Among the most frequent pathogenic mutations are R124H and R555W, both associated with granular corneal dystrophy (GCD) characterized by the early-onset formation of amorphous aggregates. The molecular mechanisms of protein aggregation in GCD are largely unknown. In this study, we determined the crystal structures of R124H, R555W, and the lattice corneal dystrophy-associated A546T. Although there were no changes in the monomeric TGFBIp structure of any mutant that would explain their propensity to aggregate, R124H and R555W demonstrated a new dimer interface in the crystal packing, which is not present in wildtype TGFBIp or A546T. This interface, as seen in both the R124H and R555W structures, involves residue 124 of the first TGFBIp molecule and 555 in the second. The interface is not permitted by the Arg124 and Arg555 residues of wildtype TGFBIp and may play a central role in the aggregation exhibited by R124H and R555W in vivo. Using cross-linking mass spectrometry and in-line size exclusion chromatography-small-angle X-ray scattering, we characterized a dimer formed by wildtype and mutant TGFBIps in solution. Dimerization in solution also involves interactions between the N- and C-terminal domains of two TGFBIp molecules but was not identical to the crystal packing dimerization. TGFBIp-targeted interventions that disrupt the R124H/R555W crystal packing dimer interface might offer new therapeutic opportunities to treat patients with GCD. Mutation-induced dimerization of transforming growth factor-beta-induced protein may drive protein aggregation in granular corneal dystrophy.,Nielsen NS, Gadeberg TAF, Poulsen ET, Harwood SL, Weberskov CE, Pedersen JS, Andersen GR, Enghild JJ J Biol Chem. 2021 Jun 4;297(1):100858. doi: 10.1016/j.jbc.2021.100858. PMID:34097874[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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