| First Author | Merritt RC | Year | 2012 |
| Journal | Curr Biol | Volume | 22 |
| Issue | 4 | Pages | 320-5 |
| PubMed ID | 22264607 | Mgi Jnum | J:182310 |
| Mgi Id | MGI:5315207 | Doi | 10.1016/j.cub.2011.12.053 |
| Citation | Merritt RC, et al. (2012) Myosin IIIB uses an actin-binding motif in its espin-1 cargo to reach the tips of actin protrusions. Curr Biol 22(4):320-5 |
| abstractText | Myosin IIIA (MYO3A) targets actin protrusion tips using a motility mechanism dependent on both motor and tail actin-binding activity [1]. We show that myosin IIIB (MYO3B) lacks tail actin-binding activity and is unable to target COS7 cell filopodia tips, yet is somehow able to target stereocilia tips. Strikingly, when MYO3B is coexpressed with espin-1 (ESPN1), a MYO3A cargo protein endogenously expressed in stereocilia [2], MYO3B targets and carries ESPN1 to COS7 filopodia tips. We show that this tip localization is lost when we remove the ESPN1 C terminus actin-binding site. We also demonstrate that, like MYO3A [2], MYO3B can elongate filopodia by transporting ESPN1 to the polymerizing end of actin filaments. The mutual dependence of MYO3B and ESPN1 for tip localization reveals a novel mechanism for the cell to regulate myosin tip localization via a reciprocal relationship with cargo that directly participates in actin binding for motility. Our results are consistent with a novel form of motility for class III myosins that requires both motor and tail domain actin-binding activity and show that the actin-binding tail can be replaced by actin-binding cargo. This study also provides a framework to better understand the late-onset hearing loss phenotype in patients with MYO3A mutations. |
