title: Molecular mechanism of fascin function in filopodial formation.
abstract: Filopodia are cell surface protrusions that are essential for cell migration. This finger-like structure is supported by rigid tightly bundled actin filaments. The protein responsible for actin bundling in filopodia is fascin. However, the mechanism by which fascin functions in filopodial formation is not clear. Here we provide biochemical, cryo-electron tomographic, and x-ray crystal structural data demonstrating the unique structural characteristics of fascin. Systematic mutagenesis studies on 100 mutants of fascin indicate that there are two major actin-binding sites on fascin. Crystal structures of four fascin mutants reveal concerted conformational changes in fascin from inactive to active states in the process of actin bundling. Mutations in any one of the actin-binding sites impair the cellular function of fascin in filopodial formation. Altogether, our data reveal the molecular mechanism of fascin function in filopodial formation.
authors.affiliation: Department of Physiology, Cornell University Weill Medical College, New York, New York 10065, USA.
authors.forename: Shengyu
authors.initials: S
authors.lastname: Yang
authors.forename: Fang-Ke
authors.initials: FK
authors.lastname: Huang
authors.forename: Jianyun
authors.initials: J
authors.lastname: Huang
authors.forename: Shuai
authors.initials: S
authors.lastname: Chen
authors.forename: Jean
authors.initials: J
authors.lastname: Jakoncic
authors.forename: Alejandra
authors.initials: A
authors.lastname: Leo-Macias
authors.forename: Ruben
authors.initials: R
authors.lastname: Diaz-Avalos
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: J Jillian
authors.initials: JJ
authors.lastname: Zhang
authors.forename: Xin-Yun
authors.initials: XY
authors.lastname: Huang
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D045744:Cell Line, Tumor; D020285:Cryoelectron Microscopy / Q000379:methods; D018360:Crystallography, X-Ray / Q000379:methods; D005786:Gene Expression Regulation; D015972:Gene Expression Regulation, Neoplastic; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry* / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods; D008958:Models, Molecular; D008968:Molecular Conformation; D009362:Neoplasm Metastasis; D011485:Protein Binding; D011487:Protein Conformation; D011554:Pseudopodia / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry; D015398:Signal Transduction
chemical_list: D000199:Actins; D002352:Carrier Proteins; D008840:Microfilament Proteins; D011994:Recombinant Proteins; C020324:fascin; D049452:Green Fluorescent Proteins