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Title: Global Structure Changes Associated with Ca2+ Activation of Full-length Human Plasma Gelsolin

Abstract

Gelsolin regulates the dynamic assembly and disassembly of the actin-based cytoskeleton in non-muscle cells and clears the circulation of filaments released following cell death. Gelsolin is a six-domain (G1-G6) protein activated by calcium via a multi-step process that involves unfolding from a compact form to a more open form in which the three actin-binding sites (on the G1, G2, and G4 subdomains) become exposed. To follow the global structural changes that accompany calcium activation of gelsolin, small-angle x-ray scattering (SAXS) data were collected for full-length human plasma gelsolin at nanomolar to millimolar concentrations of free Ca{sup 2+}. Analysis of these data showed that, upon increasing free Ca{sup 2+} levels, the radius of gyration (R{sub g}) increased nearly 12 {angstrom}, from 31.1 {+-} 0.3 to 43 {+-} 2 {angstrom}, and the maximum linear dimension (D{sub max}) of the gelsolin molecule increased 55 {angstrom}, from 100 to 155{angstrom}. Structural reconstruction of gelsolin from these data provided a striking visual tracking of the gradual Ca{sup 2+}-induced opening of the gelsolin molecule and highlighted the critical role played by the flexible linkers between homologous domains. The tightly packed architecture of calcium-free gelsolin, seen from both SAXS and x-ray crystallographic models, is already partially openedmore » up in as low as 0.5 nM Ca{sup 2+}. Our data confirm that, although the molecule springs open from 0 to 1 {mu} free Ca{sup 2+}, even higher calcium concentrations help to stabilize a more open structure, with increases in R{sub g} and D{sub max} of 2 and 15 {angstrom}, respectively. At these higher calcium levels, the SAXS-based models provide a molecular shape that is compatible with that of the crystal structures solved for Ca{sup 2+}/gelsolin C-terminal and N-terminal halves {+-} monomeric G-actin. Placement of these crystal structures within the boundaries of the SAXS-based model suggests a movement of the G1/G2 subunits that would be required upon binding to actin.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930001
Report Number(s):
BNL-80612-2008-JA
Journal ID: ISSN 0021-9258; JBCHA3; TRN: US200822%%1154
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Biological Chemistry; Journal Volume: 282; Journal Issue: 35
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ACTIN; ANIMAL CELLS; AUGMENTATION; CALCIUM; CRYSTAL STRUCTURE; DEATH; FILAMENTS; HUMAN POPULATIONS; LEVELS; MOLECULES; PLASMA; PROTEINS; SCATTERING; SHAPE; SMALL ANGLE SCATTERING; X-RAY DIFFRACTION; national synchrotron light source

Citation Formats

Ashish,F., Paine, M., Perryman, P., Yang, L., Yin, H., and Krueger, J.. Global Structure Changes Associated with Ca2+ Activation of Full-length Human Plasma Gelsolin. United States: N. p., 2007. Web. doi:10.1074/jbc.M702446200.
Ashish,F., Paine, M., Perryman, P., Yang, L., Yin, H., & Krueger, J.. Global Structure Changes Associated with Ca2+ Activation of Full-length Human Plasma Gelsolin. United States. doi:10.1074/jbc.M702446200.
Ashish,F., Paine, M., Perryman, P., Yang, L., Yin, H., and Krueger, J.. Mon . "Global Structure Changes Associated with Ca2+ Activation of Full-length Human Plasma Gelsolin". United States. doi:10.1074/jbc.M702446200.
@article{osti_930001,
title = {Global Structure Changes Associated with Ca2+ Activation of Full-length Human Plasma Gelsolin},
author = {Ashish,F. and Paine, M. and Perryman, P. and Yang, L. and Yin, H. and Krueger, J.},
abstractNote = {Gelsolin regulates the dynamic assembly and disassembly of the actin-based cytoskeleton in non-muscle cells and clears the circulation of filaments released following cell death. Gelsolin is a six-domain (G1-G6) protein activated by calcium via a multi-step process that involves unfolding from a compact form to a more open form in which the three actin-binding sites (on the G1, G2, and G4 subdomains) become exposed. To follow the global structural changes that accompany calcium activation of gelsolin, small-angle x-ray scattering (SAXS) data were collected for full-length human plasma gelsolin at nanomolar to millimolar concentrations of free Ca{sup 2+}. Analysis of these data showed that, upon increasing free Ca{sup 2+} levels, the radius of gyration (R{sub g}) increased nearly 12 {angstrom}, from 31.1 {+-} 0.3 to 43 {+-} 2 {angstrom}, and the maximum linear dimension (D{sub max}) of the gelsolin molecule increased 55 {angstrom}, from 100 to 155{angstrom}. Structural reconstruction of gelsolin from these data provided a striking visual tracking of the gradual Ca{sup 2+}-induced opening of the gelsolin molecule and highlighted the critical role played by the flexible linkers between homologous domains. The tightly packed architecture of calcium-free gelsolin, seen from both SAXS and x-ray crystallographic models, is already partially opened up in as low as 0.5 nM Ca{sup 2+}. Our data confirm that, although the molecule springs open from 0 to 1 {mu} free Ca{sup 2+}, even higher calcium concentrations help to stabilize a more open structure, with increases in R{sub g} and D{sub max} of 2 and 15 {angstrom}, respectively. At these higher calcium levels, the SAXS-based models provide a molecular shape that is compatible with that of the crystal structures solved for Ca{sup 2+}/gelsolin C-terminal and N-terminal halves {+-} monomeric G-actin. Placement of these crystal structures within the boundaries of the SAXS-based model suggests a movement of the G1/G2 subunits that would be required upon binding to actin.},
doi = {10.1074/jbc.M702446200},
journal = {Journal of Biological Chemistry},
number = 35,
volume = 282,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}