Báo cáo khoa học: Verprolin function in endocytosis and actin organization Roles of the Las17p (yeast WASP)-binding domain and a novel C-terminal actin-binding domain

Verprolin Function in Endocytosis and Actin Organization: Roles of the Las17p (yeast WASP)-Binding Domain and a Novel C-terminal Actin-Binding Domain

Authors: Thirumaran Thanabalu, Rajamuthiah Rajmohan, Lei Meng, Gang Ren, Parimala R. Vajjhala, and Alan L. Munn

Field: Molecular and Cell Biology

Document Description:

This research investigates the function of Vrp1p, the yeast ortholog of human WASP-interacting protein (WIP), in endocytosis and actin organization. Vrp1p is crucial for the polarization of the cortical actin cytoskeleton, essential for growth and endocytosis, particularly at elevated temperatures. The study focuses on the C-terminal fragment of Vrp1p (C-Vrp1p) and identifies two submodules critical for actin cytoskeleton polarization: a novel C-terminal actin-binding submodule (CABS) with a G-actin-binding domain (VH2-C), and the Las17p-binding domain (LBD). The LBD is shown to localize C-Vrp1p to membranes and the cortical actin cytoskeleton, and is sufficient to restore endocytosis and growth in Vrp1p-deficient cells at elevated temperatures. The CABS also contributes to these functions when associated with a lipid anchor. The findings highlight the importance of Las17p binding for Vrp1p membrane association and suggest that general membrane association, rather than specific targeting to the cortical actin cytoskeleton, is more critical for Vrp1p’s role in endocytosis and cell growth.

Detailed Table of Contents:

• Introduction
• Keywords
• Correspondence
• Present Address
• Results
• Function of Vrp1p C-terminal module
• Figure 1: Vrp1p domain structure
• Figure 2: C-Vrp1p charged-cluster residues K485R486 are essential for cortical actin-patch polarization, but not for endocytosis or growth at elevated temperatures.
• Table 1: Actin-patch polarization of vrp14 cells carrying vector, or plasmids expressing Vrp1p, C-Vrp1p or its derivatives.
• Figure 3: C-Vrp1p residues 465-492 containing the K485R486 charged cluster are essential for cortical actin-patch polarization, but not endocytosis or growth at elevated temperatures.
• Figure 4: C-Vrp1p residues 465-533 containing the K485R486 charged cluster directly binds G-actin and residues K485R486 are critical.
• Figure 5: The LBD of C-Vrp1p is essential for cortical actin-patch polarization, endocytosis, and growth at elevated temperature.
• Figure 6: The LBD of C-Vrp1p is necessary and sufficient for localization to cortical patches.