Regulatory Light Chain Phosphorylation and N-Terminal Extension Increase Cross-Bridge Binding and Power Output in Drosophila at In Vivo Myofilament Lattice Spacing
Regulatory Light Chain Phosphorylation and N-Terminal Extension Increase Cross-Bridge Binding and Power Output in Drosophila at In Vivo Myofilament Lattice Spacing
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DOI：
10.1016/j.bpj.2011.02.028
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发表时间：
2011-04-06
影响因子：
3.4
通讯作者：
Maughan, David W.
中科院分区：
文献类型：
--
作者：
Miller, Mark S.;Farman, Gerrie P.;Maughan, David W.
肌球蛋白调节轻链(RLC)的N端延伸和磷酸化独立地改善了果蝇的飞行性能。在这里，我们研究了RLC在化学上的功能和结构作用：四个转基因果蝇品系的不同粗丝和细丝点阵间距的剥皮纤维：拯救的空或对照(DMLC(2+))，截短的N末端延伸(Dmlc2(Delta 2-46))，破坏的肌球蛋白轻链激酶磷酸化位点(Dmlc2(S66A，S67A))和双重突变体(Dmlc2(Delta 2-46)；(S66A，S67A))N末端延伸截断和磷酸化位点中断突变降低了最大钙激活纤维的振荡功率输出和最大功率输出频率，压缩到接近体内粗丝间距，其中磷酸化位点中断突变影响更大。N-末端延伸截断和磷酸化位点中断突变导致的功率输出参数的减少是由于强结合交叉桥的数量和肌球蛋白力产生速率的减少，而磷酸化位点中断突变的参数减少更大还与肌球蛋白附着时间的减少有关。跨桥动力学中的磷酸化和N-末端延伸依赖的增强证实了先前的结构数据，这表明这些RLC属性在将肌球蛋白头部移动和定位到肌动蛋白靶点方面起到补充作用，从而增加纤维和整个果蝇的发电量。
The N-terminal extension and phosphorylation of the myosin regulatory light chain (RLC) independently improve Drosophila melanogaster flight performance. Here we examine the functional and structural role of the RLC in chemically :skinned fibers at various thick and thin filament lattice spacings from four transgenic Drosophila lines: rescued null or control (Dmlc(2+)), truncated N-terminal extension (Dmlc2(Delta 2-46)), disrupted myosin light chain kinase phosphorylation sites (Dmlc2(S66A,S67A)) and dual mutant (Dmlc2(Delta 2-46); (S66A,S67A)) The N-terminal extension truncation and phosphorylation sites disruption mutations decreased oscillatory power output and the frequency of maximum power output in maximally Ca2+-activated fibers compressed to near in vivo inter-thick filament spacing, with the phosphorylation sites disruption mutation having a larger affect. The diminished power output parameters with the N-terminal extension truncation and phosphorylation sites disruption mutations were due to the reduction of the number of strongly-bound cross-bridges and rate of myosin force producion, with the larger parameter reductions in the phosphorylation sites disruption mutation additionally related to reduced myosin attachment time. The phosphorylation and N-terminal extension-dependent boost in cross-bridge kinetics corroborates previous structural data, which indicate these RLC attributes play a complementary role in moving and orienting myosin heads toward actin target sites, thereby increasing fiber and whole fly power generation.