Molecular Characterisation of Titin N2A and Its Binding of CARP Reveals a Titin/Actin Cross-linking Mechanism.
Molecular Characterisation of Titin N2A and Its Binding of CARP Reveals a Titin/Actin Cross-linking Mechanism.
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DOI：
10.1016/j.jmb.2021.166901
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发表时间：
2021-04-30
影响因子：
5.6
通讯作者：
Mayans O
中科院分区：
文献类型：
--
作者：
Zhou T;Fleming JR;Lange S;Hessel AL;Bogomolovas J;Stronczek C;Grundei D;Ghassemian M;Biju A;Börgeson E;Bullard B;Linke WA;Chen J;Kovermann M;Mayans O
横纹肌通过快速上调心脏骨架蛋白重复蛋白CARP的表达来响应机械负荷，然后CARP通过与I带区域的titin N2a结合来靶向肌节。到目前为止，这种相互作用在肌肉应激反应中的作用仍然知之甚少。在这里，我们描述了肌动蛋白(UN2A)中鲤鱼受体位置的分子结构及其与鲤鱼的结合。我们发现Titin UN2A含有一个中心的三螺旋束折叠(长度约为45个残基)，该折叠通过部分螺旋含量的长而灵活的连接子连接到N-末端和C-末端的免疫球蛋白结构域。鲤鱼通过在UN2A的三螺旋折叠、C-末端接头序列和免疫球蛋白81的BC环中与α-发夹结合，共同形成一个广泛的结合界面。突变试验表明，CARP/N2A关联经受住了titin N2A的序列变化，我们利用这一信息评估了85个人类单核苷酸变体。此外，肌动蛋白的共沉淀、在C2C12细胞中的共转染、心脏裂解物上的蛋白质组学以及鲤鱼浸泡的肌原纤维的机械反应表明，鲤鱼诱导肌蛋白和肌动蛋白肌丝的交联，从而增加肌原纤维的硬度。我们得出结论，鲤鱼作为肌节中力输出的调节器，在超负荷压力下保持肌肉的机械性能。
Striated muscle responds to mechanical overload by rapidly up-regulating the expression of the cardiac ankyrin repeat protein, CARP, which then targets the sarcomere by binding to titin N2A in the I-band region. To date, the role of this interaction in the stress response of muscle remains poorly understood. Here, we characterise the molecular structure of the CARP-receptor site in titin (UN2A) and its binding of CARP. We find that titin UN2A contains a central three-helix bundle fold (ca 45 residues in length) that is joined to N- and C-terminal flanking immunoglobulin domains by long, flexible linkers with partial helical content. CARP binds titin by engaging an α-hairpin in the three-helix fold of UN2A, the C-terminal linker sequence, and the BC loop in Ig81, which jointly form a broad binding interface. Mutagenesis showed that the CARP/N2A association withstands sequence variations in titin N2A and we use this information to evaluate 85 human single nucleotide variants. In addition, actin co-sedimentation, co-transfection in C2C12 cells, proteomics on heart lysates, and the mechanical response of CARP-soaked myofibrils imply that CARP induces the cross-linking of titin and actin myofilaments, thereby increasing myofibril stiffness. We conclude that CARP acts as a regulator of force output in the sarcomere that preserves muscle mechanical performance upon overload stress.
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DOI：
10.1083/jcb.200104016
发表时间：
2001-09-03
期刊：
The Journal of cell biology
影响因子：
--
作者：
Kulke M;Neagoe C;Kolmerer B;Minajeva A;Hinssen H;Bullard B;Linke WA
通讯作者：
Linke WA
影响因子：
5.5
作者：
Barash, Ilona A.;Bang, Marie-Louise;Lieber, Richard L.
通讯作者：
Lieber, Richard L.
DOI：
10.1002/ar.22968
发表时间：
2014-09
影响因子：
2
作者：
Lun, Alexander Shiang;Chen, Ju;Lange, Stephan
通讯作者：
Lange, Stephan
影响因子：
2.7
作者：
Berjanskii, Mark V.;Wishart, David S.
通讯作者：
Wishart, David S.
影响因子：
3.6
作者：
Clos, Lawrence J., II;Jofre, M. Fransisca;Markley, John L.
通讯作者：
Markley, John L.