5j1i
Structure of the spectrin repeats 7, 8, and 9 of the plakin domain of plectin
Structural highlights
DiseasePLEC_HUMAN Defects in PLEC are the cause of epidermolysis bullosa simplex with pyloric atresia (EBS-PA) [MIM:612138. EBS-PA is an autosomal recessive genodermatosis characterized by severe skin blistering at birth and congenital pyloric atresia. Death usually occurs in infancy. This disorder is allelic to MD-EBS.[1] [2] [3] Defects in PLEC are the cause of epidermolysis bullosa simplex with muscular dystrophy (MD-EBS) [MIM:226670. MD-EBS is an autosomal recessive disorder characterized by epidermal blister formation at the level of the hemidesmosome and associated with late-onset muscular dystrophy. Defects in PLEC are the cause of epidermolysis bullosa simplex Ogna type (O-EBS) [MIM:131950; also called epidermolysis bullosa simplex 1. O-EBS is a form of intraepidermal epidermolysis bullosa characterized by generalized skin bruising, skin fragility with non-scarring blistering and small hemorrhagic blisters on hands. At the ultrastructural level, it is differentiated from classical cases of K-EBS, WC-EBS and DM-EBS, by the occurrence of blisters originating in basal cells above hemidesmosomes, and abnormal hemidesmosome intracellular attachment plates. Defects in PLEC are the cause of limb-girdle muscular dystrophy type 2Q (LGMD2Q) [MIM:613723. An autosomal recessive degenerative myopathy characterized by early childhood onset of proximal muscle weakness. Note=A 9 bp deletion containing the initiation codon in exon 1f of PLEC have been found in limb-girdle muscular dystrophy patients. The mutation results in deficient expression of isoform 9 and disorganization of the myofibers, without any effect on the skin.[4] [5] FunctionPLEC_HUMAN Interlinks intermediate filaments with microtubules and microfilaments and anchors intermediate filaments to desmosomes or hemidesmosomes. Could also bind muscle proteins such as actin to membrane complexes in muscle. May be involved not only in the filaments network, but also in the regulation of their dynamics. Structural component of muscle. Isoform 9 plays a major role in the maintenance of myofibers integrity.[6] [7] Publication Abstract from PubMedPlakins are large multi-domain proteins that interconnect cytoskeletal structures. Plectin is a prototypical plakin that tethers intermediate filaments to membrane-associated complexes. Most plakins contain a plakin domain formed by up to nine spectrin repeats (SR1 to SR9) and an SH3 domain. The plakin domains of plectin and other plakins harbor binding sites for junctional proteins. We have combined X-ray crystallography with small angle X-ray scattering (SAXS) to elucidate the structure of the plakin domain of plectin, extending our previous analysis of the SR1 to SR5 region. Two crystal structures of the SR5-SR6 region allowed us to characterize its uniquely wide inter-repeat conformational variability. We also report the crystal structures of the SR7-SR8 region, refined to 1.8 A, and the SR7-SR9 at lower resolution. The SR7-SR9 region, which is conserved in all other plakin domains, forms a rigid segment stabilized by uniquely extensive inter-repeat contacts mediated by unusually long helices in SR8 and SR9. Using SAXS we show that in solution the SR3-SR6 and SR7-SR9 regions are rod-like segments and that the SR3-SR9 of plectin has an extended shape with a small central kink. Other plakins, such as bullous pemphigoid antigen 1 and microtubule and actin crosslinking factor 1, are likely to have similar extended plakin domains. In contrast, desmoplakin has a two-segment structure with a central flexible hinge. The continuous versus segmented structures of the plakin domains of plectin and desmoplakin give insight about how different plakins might respond to tension and transmit mechanical signals. The Structure of the Plakin Domain of Plectin Reveals an Extended Rod-like Shape.,Ortega E, Manso JA, Buey RM, Carballido AM, Carabias A, Sonnenberg A, de Pereda JM J Biol Chem. 2016 Jul 13. pii: jbc.M116.732909. PMID:27413182[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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