A regular pattern of Ig super-motifs defines segmental flexibility as the elastic mechanism of the titin chain. Export

@article{citeulike:2305669, abstract = {Myofibril elasticity, critical to muscle function, is dictated by the intrasarcomeric filament titin, which acts as a molecular spring. To date, the molecular events underlying the mechanics of the folded titin chain remain largely unknown. We have elucidated the crystal structure of the 6-Ig fragment I65-I70 from the elastic I-band fraction of titin and validated its conformation in solution using small angle x-ray scattering. The long-range properties of the chain have been visualized by electron microscopy on a 19-Ig fragment and modeled for the full skeletal tandem. Results show that conserved Ig-Ig transition motifs generate high-order in the structure of the filament, where conformationally stiff segments interspersed with pliant hinges form a regular pattern of dynamic super-motifs leading to segmental flexibility in the chain. Pliant hinges support molecular shape rearrangements that dominate chain behavior at moderate stretch, whereas stiffer segments predictably oppose high stretch forces upon full chain extension. There, librational entropy can be expected to act as an energy barrier to prevent Ig unfolding while, instead, triggering the unraveling of flanking springs formed by proline, glutamate, valine, and lysine (PEVK) sequences. We propose a mechanistic model based on freely jointed rigid segments that rationalizes the response to stretch of titin Ig-tandems according to molecular features.}, address = {Division of Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland;}, author = {von Castelmur, Eleonore and Marino, Marco and Svergun, Dmitri I I. and Kreplak, Laurent and Ucurum-Fotiadis, Z\"{o}hre and Konarev, Petr V V. and Urzhumtsev, Alexandre and Labeit, Dietmar and Labeit, Siegfried and Mayans, Olga}, citeulike-article-id = {2305669}, citeulike-linkout-0 = {http://dx.doi.org/10.1073/pnas.0707163105}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/18212128}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=18212128}, day = {22}, doi = {10.1073/pnas.0707163105}, issn = {1091-6490}, journal = {Proc Natl Acad Sci U S A}, keywords = {ig-like, protein-mechanics}, month = {January}, posted-at = {2008-01-30 02:01:41}, priority = {0}, title = {A regular pattern of Ig super-motifs defines segmental flexibility as the elastic mechanism of the titin chain.}, url = {http://dx.doi.org/10.1073/pnas.0707163105}, year = {2008} }

TY - JOUR ID - citeulike:2305669 L3 - citeulike-article-id:2305669 N2 - Myofibril elasticity, critical to muscle function, is dictated by the intrasarcomeric filament titin, which acts as a molecular spring. To date, the molecular events underlying the mechanics of the folded titin chain remain largely unknown. We have elucidated the crystal structure of the 6-Ig fragment I65-I70 from the elastic I-band fraction of titin and validated its conformation in solution using small angle x-ray scattering. The long-range properties of the chain have been visualized by electron microscopy on a 19-Ig fragment and modeled for the full skeletal tandem. Results show that conserved Ig-Ig transition motifs generate high-order in the structure of the filament, where conformationally stiff segments interspersed with pliant hinges form a regular pattern of dynamic super-motifs leading to segmental flexibility in the chain. Pliant hinges support molecular shape rearrangements that dominate chain behavior at moderate stretch, whereas stiffer segments predictably oppose high stretch forces upon full chain extension. There, librational entropy can be expected to act as an energy barrier to prevent Ig unfolding while, instead, triggering the unraveling of flanking springs formed by proline, glutamate, valine, and lysine (PEVK) sequences. We propose a mechanistic model based on freely jointed rigid segments that rationalizes the response to stretch of titin Ig-tandems according to molecular features. JF - Proc Natl Acad Sci U S A SN - 1091-6490 AD - Division of Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland; TI - A regular pattern of Ig super-motifs defines segmental flexibility as the elastic mechanism of the titin chain. KW - ig-like KW - protein-mechanics AU - von Castelmur, Eleonore AU - Marino, Marco AU - Svergun, Dmitri I AU - Kreplak, Laurent AU - Ucurum-Fotiadis, Zöhre AU - Konarev, Petr V AU - Urzhumtsev, Alexandre AU - Labeit, Dietmar AU - Labeit, Siegfried AU - Mayans, Olga PY - 2008/01/22/ UR - http://dx.doi.org/10.1073/pnas.0707163105 ER -