期刊
JOURNAL OF CELL SCIENCE
卷 120, 期 10, 页码 1779-1790出版社
COMPANY BIOLOGISTS LTD
DOI: 10.1242/jcs.007641
关键词
coronin; actin; cofilin; arp2/3; FRAP
类别
资金
- NCI NIH HHS [CA-16086, 1U54CA119343] Funding Source: Medline
Coronins are conserved F-actin binding proteins that have been implicated in a variety of processes including fibroblast migration, phagocytosis, and chemotaxis. Recent data from our lab indicate that coronin 1B coordinates Arp2/3-dependent actin filament nucleation and cofilin-mediated filament turnover at the leading edge of migrating fibroblasts. Analysis of coronin function has been hampered by the lack of a clear understanding of how coronin interacts with F-actin. Here, we identify a surface-exposed conserved arginine residue at position 30 (R30), which is crucial for coronin 1B binding to F-actin both in vitro and in vivo. Using actin co-sedimentation, we demonstrate that coronin 1B binds with high affinity to ATP/ADP-P-i -F-actin (170 nM) and with 47-fold lower affinity to ADP-F-actin (8 mu M). In contrast to a previous study, we find no evidence for enhanced cofilin binding to F-actin in the presence of either coronin 1B or coronin 1A. Instead, we find that coronin 1B protects actin filaments from cofilin-induced depolymerization. Consistent with an important role for interactions between coronin 1B and F- actin in vivo, an R30D coronin mutant that does not bind F- actin localizes inefficiently to the leading edge. Furthermore, our analysis indicates that F- actin binding is absolutely required for coronin 1B to exert its effects on whole-cell motility and lamellipodial dynamics.
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