uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Calcium, pH and ATP regulation of the gelsolin superfamily of proteins
Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
Institute of Molecular and Cell Biology, A*STAR, Singapore.
Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
Department of Chemistry and Centre for Blood Research, Life Sciences Institute, The University of British Columbia, Canada.
Show others and affiliations
(English)Manuscript (Other (popular science, discussion, etc.))
Abstract [en]

CapG, adseverin, gelsolin and villin are members of the gelsolin family of calcium-sensitive regulators of actin filament dynamics. While they display some common characteristics in their interactions with and activities toward actin, they each possess unique features in their architectures and in their functions. We have probed their similarities and differences by determining the effects of Ca2+, pH, and ATP on their structures. Each undergoes conformational changes associated with activation at neutral pH when only a fraction of their potential Ca2+-binding sites is occupied. Gelsolin, villin and adseverin exhibit local minima in thermal stability in environments containing approximately 25 nM free Ca2+. The thermal stability of CapG steadily increases through this range of free Ca2+ concentrations. All four proteins share an ability to sequester actin monomers in the presence of micromolar free Ca2+, enhancing the depolymerization of F-actin. Acidic conditions at non-denaturing pH values induce a reduction in thermal stability of all four proteins. However, low pH only induces the exposure of the actin-binding sites for adseverin and gelsolin, in the absence of free Ca2+. Gelsolin alone is able to bind ATP, which stabilizes it against thermal denaturation.

URN: urn:nbn:se:uu:diva-98742OAI: oai:DiVA.org:uu-98742DiVA: diva2:201092
Available from: 2009-03-03 Created: 2009-03-03 Last updated: 2010-01-14
In thesis
1. Structural and Functional Studies of Gelsolin Family Proteins
Open this publication in new window or tab >>Structural and Functional Studies of Gelsolin Family Proteins
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The actin cytoskeleton is a complex structure that performs a wide range of cellular functions including: cell locomotion, cytokinesis, chemotaxis, signal transduction and apoptosis. The coordinated assembly and disassembly of actin filaments is controlled by a multitude of proteins (ABPs) in the cell. There are over 160 actin-binding proteins known, which with actin, account for approximately 25% of cellular protein. ABPs are classified to several major groups based on their sequence identity and functions.

In this work, we have elucidated the crystal structure of ATP bound gelsolin. We have shown that ATP binding involves the two halves of gelsolin through forming numerous polar and hydrophobic contacts. Amino acid residues that form the ATP-binding sites in inactive gelsolin are widely dispersed in the activated molecule, and hence, ATP binding is disrupted on gelsolin activation. This suggests that binding of ATP may modulate the sensitivity of gelsolin to calcium ions.

The structure of human gelsolin domains 1-3 bound to actin revealed a calcium ion bound to domain 2. Here, we demonstrated that only two calcium ions are needed to activate geloslin. We speculate that this domain 2 calcium ion and the one in domain 6 participate in the initial activation of gelsolin.

The crystal structure of the activated adseverin C-terminus is highly similar to that of the C-terminus of gelsolin. Comparative analysis suggests that, like the gelsolin C-terminus, adseverin will also contact actin through domain 4 and domain 6. Biochemical experiments, presented here, show that a minimum of one calcium is required for adseverin to depolymerizing actin filaments compared to two calcium for gelsolin. We speculate that this is due to the lack of the C-terminal extension in adseverin.

We undertook a comparative analysis of four members of the gelsolin family proteins, gelsolin, adseverin, villin and capG, in the aspects of their calcium binding, pH activation and ATP binding. The results show that only gelsolin and adseverin are able to depolymerize actin filaments at pH < 6 in the absence of calcium ions and only gelsolin bind to ATP.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 41 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 427
National Category
Structural Biology
urn:nbn:se:uu:diva-98226 (URN)978-91-554-7434-8 (ISBN)
Public defence
2009-03-25, C10:301, Uppsala Biomedical Center (BMC), Husargatan 3, Uppsala, 09:15 (English)
Available from: 2009-03-02 Created: 2009-02-18 Last updated: 2010-01-13Bibliographically approved

Open Access in DiVA

No full text

By organisation
Department of Medical Biochemistry and Microbiology

Search outside of DiVA

GoogleGoogle Scholar

Total: 256 hits
ReferencesLink to record
Permanent link

Direct link