Speaker
Dr
Teemu Ikonen
(Paul Scherrer Institut)
Description
The Spire protein represents a new class of actin nucleation factors which contain ca. 25 amino acid long actin-binding motifs called the WH2 repeats. We have applied small angle X-ray scattering to study the architecture of several Spire/actin complexes, including the native N-terminal part of Spire (SpireNT). Spire forms stable longitudinal-like complexes, with actin loosely positioned along the stretch of WH2 domains. Actin together with the WH2 domain constitutes a rigid unit and these units are linked by unstructured and flexible linkers. Analysis of the orientation of actin domains within the complexes reveals a high rotational mobility in single actin/WH2 modules. The Spire/actin nucleus shows an open and flexible conformation, but the longitudinal-like shape is preserved. The three most unusual properties of the Spire constructs upon their interaction with actin are (i) nucleation of actin polymerization at substoichiometric Spire WH2/actin ratios, (ii) a dose-dependent decrease of polymerization-induced fluorescence signal during steady state, and (iii) an extremely fast disintegration of actin filaments upon addition of Spire constructs that contain WH2 domains.
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Soft Condensed Matter
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Poster
Primary authors
Dr
Teemu Ikonen
(Paul Scherrer Institut)
Dr
Tomasz Sitar
(Max-Planck-Institut für Biochemie, 82152 Martinsried, Germany)
Co-authors
Ms
Anna M. Ducka
(Max-Planck-Institut für Biochemie, 82152 Martinsried, Germany)
Dr
Julia Gallinger
(Institute for Anatomy and Cell Biology, Ludwig-Maximilians University, 80336 München, Germany)
Dr
Michael Schleicher
(Institute for Anatomy and Cell Biology, Ludwig-Maximilians University, 80336 München, Germany)
Prof.
Robert Huber
(Max-Planck-Institut für Biochemie, 82152 Martinsried, Germany)
Prof.
Tad A. Holak
(Max-Planck-Institut für Biochemie, 82152 Martinsried, Germany)
