Effects of Arp2 and Arp3 nucleotide-binding pocket mutations on Arp2/3 complex function |
| |
Authors: | Martin Adam C Xu Xiao-Ping Rouiller Isabelle Kaksonen Marko Sun Yidi Belmont Lisa Volkmann Niels Hanein Dorit Welch Matthew Drubin David G |
| |
Institution: | Barker Hall, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA. |
| |
Abstract: | Contributions of actin-related proteins (Arp) 2 and 3 nucleotide state to Arp2/3 complex function were tested using nucleotide-binding pocket (NBP) mutants in Saccharomyces cerevisiae. ATP binding by Arp2 and Arp3 was required for full Arp2/3 complex nucleation activity in vitro. Analysis of actin dynamics and endocytosis in mutants demonstrated that nucleotide-bound Arp3 is particularly important for Arp2/3 complex function in vivo. Severity of endocytic defects did not correlate with effects on in vitro nucleation activity, suggesting that a critical Arp2/3 complex function during endocytosis may be structural rather than catalytic. A separate class of Arp2 and Arp3 NBP mutants suppressed phenotypes of mutants defective for actin nucleation. An Arp2 suppressor mutant increased Arp2/3 nucleation activity. Electron microscopy of Arp2/3 complex containing this Arp2 suppressor identified a structural change that also occurs upon Arp2/3 activation by nucleation promoting factors. These data demonstrate the importance of Arp2 and Arp3 nucleotide binding for nucleating activity, and Arp3 nucleotide binding for maintenance of cortical actin cytoskeleton cytoarchitecture. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|