Haugwitz M, Noegel A A, Karakesisoglou J, Schleicher M
Max-Planck-Institut für Biochemie, Martinsried, Federal Republic of Germany.
Cell. 1994 Oct 21;79(2):303-14. doi: 10.1016/0092-8674(94)90199-6.
To study in vivo functions of the ubiquitous actin-binding protein profilin, we generated by antisense and gene disruption techniques Dictyostelium mutants that lack one or both of the profilin isoforms. Whereas the single mutants showed an essentially unchanged phenotype, the behavior of the double mutant was drastically altered. Motility was significantly reduced, single cells were up to 10 times larger than wild-type cells and showed a broad rim of filamentous actin below the plasma membrane, the filamentous actin concentration was increased by about 60%-70%, and development was blocked prior to fruiting body formation. Furthermore, double mutants could not be grown in shaking culture under normal conditions, reflecting an impaired cytokinesis. The aberrant phenotype could be rescued by reintroducing a functional profilin I or profilin II gene. The data in this study suggest that profilin functions in Dictyostelium amoebae primarily as an actin-sequestering protein.
为了研究普遍存在的肌动蛋白结合蛋白（肌动蛋白单体结合蛋白）的体内功能，我们利用反义技术和基因破坏技术构建了缺少一种或两种肌动蛋白单体结合蛋白亚型的盘基网柄菌突变体。虽然单突变体表现出基本不变的表型，但双突变体的行为却发生了显著改变。运动能力显著降低，单细胞比野生型细胞大10倍，并且在质膜下方显示出宽阔的丝状肌动蛋白边缘，丝状肌动蛋白浓度增加了约60%-70%，并且在子实体形成之前发育就被阻断。此外，双突变体在正常条件下不能在振荡培养中生长，这反映了胞质分裂受损。通过重新引入功能性的肌动蛋白单体结合蛋白I或肌动蛋白单体结合蛋白II基因，可以挽救异常表型。本研究中的数据表明，肌动蛋白单体结合蛋白在盘基网柄菌变形虫中的功能主要是作为一种肌动蛋白隔离蛋白。
