2rq8
Solution NMR structure of titin I27 domain mutant
Structural highlights
DiseaseTITIN_HUMAN Defects in TTN are the cause of hereditary myopathy with early respiratory failure (HMERF) [MIM:603689; also known as Edstrom myopathy. HMERF is an autosomal dominant, adult-onset myopathy with early respiratory muscle involvement.[1] Defects in TTN are the cause of familial hypertrophic cardiomyopathy type 9 (CMH9) [MIM:613765. Familial hypertrophic cardiomyopathy is a hereditary heart disorder characterized by ventricular hypertrophy, which is usually asymmetric and often involves the interventricular septum. The symptoms include dyspnea, syncope, collapse, palpitations, and chest pain. They can be readily provoked by exercise. The disorder has inter- and intrafamilial variability ranging from benign to malignant forms with high risk of cardiac failure and sudden cardiac death.[2] Defects in TTN are the cause of cardiomyopathy dilated type 1G (CMD1G) [MIM:604145. Dilated cardiomyopathy is a disorder characterized by ventricular dilation and impaired systolic function, resulting in congestive heart failure and arrhythmia. Patients are at risk of premature death.[3] [4] [5] Defects in TTN are the cause of tardive tibial muscular dystrophy (TMD) [MIM:600334; also known as Udd myopathy. TMD is an autosomal dominant, late-onset distal myopathy. Muscle weakness and atrophy are usually confined to the anterior compartment of the lower leg, in particular the tibialis anterior muscle. Clinical symptoms usually occur at age 35-45 years or much later.[6] [7] Defects in TTN are the cause of limb-girdle muscular dystrophy type 2J (LGMD2J) [MIM:608807. LGMD2J is an autosomal recessive degenerative myopathy characterized by progressive weakness of the pelvic and shoulder girdle muscles. Severe disability is observed within 20 years of onset. Defects in TTN are the cause of early-onset myopathy with fatal cardiomyopathy (EOMFC) [MIM:611705. Early-onset myopathies are inherited muscle disorders that manifest typically from birth or infancy with hypotonia, muscle weakness, and delayed motor development. EOMFC is a titinopathy that, in contrast with the previously described examples, involves both heart and skeletal muscle, has a congenital onset, and is purely recessive. This phenotype is due to homozygous out-of-frame TTN deletions, which lead to a total absence of titin's C-terminal end from striated muscles and to secondary CAPN3 depletion.[8] FunctionTITIN_HUMAN Key component in the assembly and functioning of vertebrate striated muscles. By providing connections at the level of individual microfilaments, it contributes to the fine balance of forces between the two halves of the sarcomere. The size and extensibility of the cross-links are the main determinants of sarcomere extensibility properties of muscle. In non-muscle cells, seems to play a role in chromosome condensation and chromosome segregation during mitosis. Might link the lamina network to chromatin or nuclear actin, or both during interphase.[9] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedPoint mutations in proteins can have different effects on protein stability depending on the mechanism of unfolding. In the most interesting case of I27, the Ig-like module of the muscle protein titin, one point mutation (Y9P) yields opposite effects on protein stability during denaturant-induced 'global unfolding' versus 'vectorial unfolding' by mechanical pulling force or cellular unfolding systems. Here we assessed by NMR the reason for the different effects of the Y9P mutation of I27 on the overall molecular stability and N-terminal unraveling. We found that the Y9P mutation causes a conformational change that is transmitted through beta-sheet structures to reach the central hydrophobic core in the interior and alters its accessibility to bulk solvent, which leads to destabilization of the hydrophobic core. On the other hand, the Y9P mutation causes a bend in the backbone structure, which leads to the formation of a more stable N-terminal structure probably through enhanced hydrophobic interactions. Structural basis for unfolding pathway-dependent stability of proteins: Vectorial unfolding vs. global unfolding.,Yagawa K, Yamano K, Oguro T, Maeda M, Sato T, Momose T, Kawano S, Endo T Protein Sci. 2010 Jan 21. PMID:20095049[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
| ||||||||||||||||||
