肌動蛋白,，肌球蛋白以及肌聯(lián)蛋白在肌肉的收縮過程中扮演著重要的角色，歐洲分子生物學實驗室（EMBL）的科學家目前正在對另外一種肌肉蛋白-myomesin進行實驗研究,，這種蛋白可以拉長至自身長度的2.5倍,，以一種前所未聞的方式進行展開，2月14日,，相關的研究成果發(fā)表在了國際雜志PLoS Biology上,。
myomesin連接著肌絲進行伸縮，所以說這種蛋白是很有彈性的,，實驗室的研究者Matthias Wilmanns和他的研究伙伴運用X-射線晶體學方法,，X-射線散射方法,，電鏡及原子力顯微鏡檢查等方法來揭示這種蛋白伸展能力的機制，研究者們通過大量實驗發(fā)現(xiàn),，myomesin蛋白的拉伸部位就像是串聯(lián)珍珠的細繩子,，拉著免疫球蛋白結構域，就像我們知道的α-螺旋一樣,，將彈性帶隔離在外,。
當這種蛋白被拆解的時候，中間的單環(huán)會展開,，然而免疫球蛋白結構域并不會展開,，作者新的研究發(fā)現(xiàn)給科學界在免疫球蛋白結構域是否存在潛在的彈性提供了新的線索，下一步,，Wilmanns教授將和他的研究團隊將會研究myomesin蛋白在身體代謝中扮演的角色,，并且確定這種蛋白如何和其它肌肉成分進行反應和交流的。（生物谷：T.Shen編譯）
doi:10.1371/journal.pbio.1001261
PMC:
PMID:
Superhelical Architecture of the Myosin Filament-Linking Protein Myomesin with Unusual Elastic Properties
Nikos Pinotsis1,2#¤, Spyros D. Chatziefthimiou1,3#, Felix Berkemeier4, Fabienne Beuron2, Irene M. Mavridis3, Petr V. Konarev1, Dmitri I. Svergun1, Edward Morris2, Matthias Rief4, Matthias Wilmanns1*
Active muscles generate substantial mechanical forces by the contraction/relaxation cycle, and, to maintain an ordered state, they require molecular structures of extraordinary stability. These forces are sensed and buffered by unusually long and elastic filament proteins with highly repetitive domain arrays. Members of the myomesin protein family function as molecular bridges that connect major filament systems in the central M-band of muscle sarcomeres, which is a central locus of passive stress sensing. To unravel the mechanism of molecular elasticity in such filament-connecting proteins, we have determined the overall architecture of the complete C-terminal immunoglobulin domain array of myomesin by X-ray crystallography, electron microscopy, solution X-ray scattering, and atomic force microscopy. Our data reveal a dimeric tail-to-tail filament structure of about 360 Å in length, which is folded into an irregular superhelical coil arrangement of almost identical α-helix/domain modules. The myomesin filament can be stretched to about 2.5-fold its original length by reversible unfolding of these linkers, a mechanism that to our knowledge has not been observed previously. Our data explain how myomesin could act as a highly elastic ribbon to maintain the overall structural organization of the sarcomeric M-band. In general terms, our data demonstrate how repetitive domain modules such as those found in myomesin could generate highly elastic protein structures in highly organized cell systems such as muscle sarcomeres.
