González-Rodríguez Victoria E, Garrido Carlos, Cantoral Jesús M, Schumacher Julia
Departamento de Biomedicina, Biotecnología y Salud Pública, Laboratorio de Microbiología, Facultad de Ciencias de Mar y Ambientales, Instituto Universitario de Investigación Vitivinícola y Agroalimentaria (IVAGRO), Universidad de Cádiz, Polígono Río San Pedro, 11510 Puerto Real, Spain.
Institut für Biologie und Biotechnologie der Pflanzen (IBBP), Westfälische Wilhelms-Universität Münster, Schlossplatz 8, 48143 Münster, Germany.
Fungal Biol. 2016 Oct;120(10):1225-35. doi: 10.1016/j.funbio.2016.07.007. Epub 2016 Jul 22.
Filamentous (F-) actin is an integral part of the cytoskeleton allowing for cell growth, intracellular motility, and cytokinesis of eukaryotic cells. Its assembly from G-actin monomers and its disassembly are tightly regulated processes involving a number of actin-binding proteins (ABPs) such as F-actin nucleators and cross-linking proteins. F-actin capping protein (CP) is an alpha/beta heterodimer known from yeast and higher eukaryotes to bind to the fast growing ends of the actin filaments stabilizing them. In this study, we identified the orthologs of the two CP subunits, named BcCPA1 and BcCPB1, in the plant pathogenic fungus Botrytis cinerea and showed that the two proteins physically interact in a yeast two-hybrid approach. GFP-BcCPA1 fusion proteins were functional and localized to the assumed sites of F-actin accumulation, i.e. to the hyphal tips and the sites of actin ring formation. Deletion of bccpa1 had a profound effect on hyphal growth, morphogenesis, and virulence indicating the importance of F-actin capping for an intact actin cytoskeleton. As polarized growth - unlike septum formation - is impaired in the mutants, it can be concluded that the organization and/or localization of actin patches and cables are disturbed rather than the functionality of the actin rings.
丝状（F-）肌动蛋白是细胞骨架的一个组成部分，它支持真核细胞的生长、细胞内运动及胞质分裂。其由G-肌动蛋白单体组装及解聚是受严格调控的过程，涉及许多肌动蛋白结合蛋白（ABP），如F-肌动蛋白成核蛋白和交联蛋白。F-肌动蛋白封端蛋白（CP）是一种α/β异二聚体，在酵母和高等真核生物中已知其可结合到肌动蛋白丝快速生长的末端并使其稳定。在本研究中，我们在植物病原真菌灰葡萄孢中鉴定出了两个CP亚基的直系同源物，命名为BcCPA1和BcCPB1，并通过酵母双杂交方法表明这两种蛋白可发生物理相互作用。GFP-BcCPA1融合蛋白具有功能，并定位于假定的F-肌动蛋白积累位点，即菌丝尖端和肌动蛋白环形成位点。bccpa1的缺失对菌丝生长、形态发生和毒力有深远影响，这表明F-肌动蛋白封端对于完整的肌动蛋白细胞骨架很重要。由于突变体中极性生长（与隔膜形成不同）受损，因此可以得出结论，肌动蛋白斑和肌动蛋白丝束的组织和/或定位受到干扰，而不是肌动蛋白环的功能。
