Open this publication in new window or tab >>2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]
Cellular processes like motility, chemotaxis, phagocytosis and morphogenesis are dependent on the dynamic regulation of the actin cytoskeleton. This cytoskeleton system is tightly controlled by a number of diverse actin-binding proteins (ABPs) by various mechanisms described as nucleation, polymerization, capping, severing, depolymerization and sequestration. The ABPs are grouped based on sequence identity as in the Wiskott-Aldrich Syndrome protein homology domain 2 (WH2), and the calponin homology domain (CH) containing proteins.
In this work, we elucidate the crystal structures of hybrids of gelsolin domain 1 with thymosin β4, ciboulot domain 2, and the second WH2 domain of N-WASP each bound to actin. We show that the single WH2 motif containing protein thymosin β4 in part sequesters actin by binding its pointed end via a C-terminal helix. This interaction prevents the addition of bound actin protomers to the barbed end of the filament. We propose that sequence variations in some WH2 motifs conferred F-actin binding ability to multiple repeat-containing proteins. These F-actin binding domains interact with the barbed end of a filament and the adjacent WH2 motifs are then freed to add their bound actin to the growing filament end. We demonstrate the binding of ciboulot domains 2 and 3 to both G- and F-actin and that full length ciboulot is capable of binding two actin monomers simultaneously.
We have also cloned, expressed, purified and crystallized rod domains 14-16 from the actin crosslinking protein a-filamin. Preliminary X-ray crystallography data gives us hope that we shall be able to solve the structure of this triple domain repeat.
Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. p. 54
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 182
Keywords
Biochemistry, Actin, Thymosin, Ciboulot, N-WASP, Filamin, Calponin homology domain, WH2, Protein Crystallography, Biokemi
Identifiers
urn:nbn:se:uu:diva-7188 (URN)91-554-6679-6 (ISBN)
Public defence
2006-11-08, C10:301, BMC, Hursagata 3, SE 751 23, Uppsala, 13:15
Opponent
Supervisors
2006-10-182006-10-18Bibliographically approved