Processivity of chimeric class V myosins
Processivity of chimeric class V myosins
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DOI：
10.1074/jbc.m510041200
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发表时间：
2006-03-03
影响因子：
4.8
通讯作者：
Trybus, KM
中科院分区：
文献类型：
--
作者：
Krementsova, EB;Hodges, AR;Trybus, KM
非传统的肌球蛋白V在解离肌动蛋白细丝之前需要沿着肌动蛋白细丝走上36纳米的多步，从而确保其能够远距离在细胞内移动货物。在本研究中，我们通过分析小鼠肌球蛋白V和来自酵母的非进程V类肌球蛋白(Myo4p)(Reck-Peterson，S.L.，Tyska，M.J.，Novick，P.J.和Mooseker，M.S.(2001)J.Cell Biol)的嵌合体的性质，评估了影响进程行程长度的结构特征。153、1121-1126)。令人惊讶的是，在小鼠肌球蛋白V(Y-MD)的颈部和杆部含有酵母运动域的嵌合体在低盐条件下显示出比小鼠野生型更长的运行长度。小鼠肌球蛋白V的游程长度对盐的依赖性很小，而Y-MD的游程长度随着离子强度的增加而急剧减少，类似于小鼠肌球蛋白V主干中含有酵母环2的嵌合体。环2在循环的弱结合状态下与肌动蛋白上的酸性斑块结合(Volkmann，N.，Liu，H.，Hazelwood，L.，Krementsova，E.B.，Lowey，S.，Trybus，K.M.和Hanein，D.(2005)Mol.电话19,595-605)。含有酵母环2的构建物，与野生型的+6相比，没有净电荷，在稳态ATPase检测中显示出更高的肌动蛋白K-m。结果表明，带正电的环2和对肌动蛋白的高亲和力对于维持接近生理离子强度的加工能力是重要的。
Unconventional myosin V takes many 36-nm steps along an actin filament before it dissociates, thus ensuring its ability to move cargo intracellularly over long distances. In the present study we assessed the structural features that affect processive run length by analyzing the properties of chimeras of mouse myosin V and a non-processive class V myosin from yeast (Myo4p) (Reck-Peterson, S. L., Tyska, M. J., Novick, P. J., and Mooseker, M. S. (2001) J. Cell Biol. 153, 1121-1126). Surprisingly a chimera containing the yeast motor domain on the neck and rod of mouse myosin V (Y-MD) showed longer run lengths than mouse wild type at low salt. Run lengths of mouse myosin V showed little salt dependence, whereas those of Y-MD decreased steeply with ionic strength, similar to a chimera containing yeast loop 2 in the mouse myosin V backbone. Loop 2 binds to acidic patches on actin in the weak binding states of the cycle (Volkmann, N., Liu, H., Hazelwood, L., Krementsova, E. B., Lowey, S., Trybus, K. M., and Hanein, D. (2005) Mol. Cell 19, 595-605). Constructs containing yeast loop 2, which has no net charge compared with +6 for wild type, showed a higher K-m for actin in steady-state ATPase assays. The results imply that a positively charged loop 2 and a high affinity for actin are important to maintain processivity near physiologic ionic strength.