Jung G, Saxe C L, Kimmel A R, Hammer J A
Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, Bethesda, MD 20892.
Proc Natl Acad Sci U S A. 1989 Aug;86(16):6186-90. doi: 10.1073/pnas.86.16.6186.
We have cloned and completely sequenced a gene encoding the heavy chain of Dictyostelium myosin I. Like the myosin I molecules from Acanthamoeba, the Dictyostelium myosin I heavy chain is composed of a globular head domain fused to a 45-kDa glycine-, proline-, and alanine-rich carboxyl-terminal domain, rather than the coiled-coil rod domain of conventional myosins. Comparisons of the Dictyostelium myosin I heavy-chain amino acid sequence with those of the Acanthamoeba myosins I reveal that they are highly similar throughout, including the unconventional carboxyl-terminal domains. The Dictyostelium myosin I gene is expressed in growing cells as a 3600-nucleotide mRNA. Measurements of the steady-state level of this mRNA at different times during starvation-induced aggregation and development are consistent with a role for myosin I in chemotaxis and aggregation. Generation of Dictyostelium cells lacking myosin I by gene disruption and/or antisense RNA production should provide a way to test directly the role of this nonfilamentous myosin in cell motility. These experiments will be simplified by the fact that Southern blot analyses of Dictyostelium genomic DNA are consistent with there being a single myosin I heavy-chain gene.
我们已经克隆并完全测序了编码盘基网柄菌肌球蛋白I重链的基因。与棘阿米巴的肌球蛋白I分子一样，盘基网柄菌肌球蛋白I重链由一个球状头部结构域与一个富含甘氨酸、脯氨酸和丙氨酸的45 kDa羧基末端结构域融合而成，而不是传统肌球蛋白的卷曲螺旋杆状结构域。将盘基网柄菌肌球蛋白I重链氨基酸序列与棘阿米巴肌球蛋白I的序列进行比较，发现它们在整个序列中高度相似，包括非常规的羧基末端结构域。盘基网柄菌肌球蛋白I基因在生长细胞中以3600个核苷酸的mRNA形式表达。在饥饿诱导的聚集和发育过程中不同时间对该mRNA稳态水平的测量结果与肌球蛋白I在趋化性和聚集中的作用一致。通过基因破坏和/或反义RNA产生来生成缺乏肌球蛋白I的盘基网柄菌细胞，应该能够提供一种直接测试这种非丝状肌球蛋白在细胞运动中作用的方法。由于盘基网柄菌基因组DNA的Southern印迹分析与存在单个肌球蛋白I重链基因一致，这些实验将得到简化。
