Polymerization of G-actin by hydrodynamic shear stresses

J. Borejdo, A. Muhlrad, S. J. Leibovich, A. Oplatka

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

In the absence of Ca2+ G-actin can be polymerized by the application of shear stress in low ionic strength buffer. When G-actin in low ionic strength buffer containing EGTA was sheared for predetermined times under different velocity gradients, viscosity attained a maximal value, comparable to that obtained by seeding with F-actin nuclei, at a velocity gradient of 3000 s-1 after about one hour. Such fiow-polymerized actin was indistinguishable from KCl-polymerized actin. Under similar conditions, EDTA which can bind both Ca2+ and Mg2+, gave a smaller effect than the Ca2+-chelating agent EGTA which binds Mg2+ weakly. When an Mg2+ salt was added to EDTA- or EGTA-containing buffer to give a free Mg2+ concentration of a few micromoles/liter, flow induced polymerization was significantly enhanced. It appears that occupancy of only a small fraction of the high affinity binding sites by Ca2+ prevents flow-polymerization while Mg2+ may enhance this type of polymerization by replacing Ca2+. We speculate that the shear stress induces polymerization by promoting nucleation and that Ca2+ bound to the high affinity divalent cation binding site inhibits formation of the nuclei.

Original languageEnglish
Pages (from-to)118-131
Number of pages14
JournalBBA - Protein Structure
Volume667
Issue number1
DOIs
StatePublished - 30 Jan 1981

Fingerprint

Hydrodynamics
Polymerization
Actins
Egtazic Acid
Buffers
Edetic Acid
Osmolar Concentration
Binding Sites
Divalent Cations
Chelating Agents
Viscosity
Salts

Keywords

  • G-Actin
  • Polymerization
  • Shear stress

Cite this

Borejdo, J. ; Muhlrad, A. ; Leibovich, S. J. ; Oplatka, A. / Polymerization of G-actin by hydrodynamic shear stresses. In: BBA - Protein Structure. 1981 ; Vol. 667, No. 1. pp. 118-131.
@article{fdc112a6fe344e81a16c2277aae49fc2,
title = "Polymerization of G-actin by hydrodynamic shear stresses",
abstract = "In the absence of Ca2+ G-actin can be polymerized by the application of shear stress in low ionic strength buffer. When G-actin in low ionic strength buffer containing EGTA was sheared for predetermined times under different velocity gradients, viscosity attained a maximal value, comparable to that obtained by seeding with F-actin nuclei, at a velocity gradient of 3000 s-1 after about one hour. Such fiow-polymerized actin was indistinguishable from KCl-polymerized actin. Under similar conditions, EDTA which can bind both Ca2+ and Mg2+, gave a smaller effect than the Ca2+-chelating agent EGTA which binds Mg2+ weakly. When an Mg2+ salt was added to EDTA- or EGTA-containing buffer to give a free Mg2+ concentration of a few micromoles/liter, flow induced polymerization was significantly enhanced. It appears that occupancy of only a small fraction of the high affinity binding sites by Ca2+ prevents flow-polymerization while Mg2+ may enhance this type of polymerization by replacing Ca2+. We speculate that the shear stress induces polymerization by promoting nucleation and that Ca2+ bound to the high affinity divalent cation binding site inhibits formation of the nuclei.",
keywords = "G-Actin, Polymerization, Shear stress",
author = "J. Borejdo and A. Muhlrad and Leibovich, {S. J.} and A. Oplatka",
year = "1981",
month = "1",
day = "30",
doi = "10.1016/0005-2795(81)90072-6",
language = "English",
volume = "667",
pages = "118--131",
journal = "BBA - Protein Structure",
issn = "0005-2795",
publisher = "Elsevier BV",
number = "1",

}

Polymerization of G-actin by hydrodynamic shear stresses. / Borejdo, J.; Muhlrad, A.; Leibovich, S. J.; Oplatka, A.

In: BBA - Protein Structure, Vol. 667, No. 1, 30.01.1981, p. 118-131.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Polymerization of G-actin by hydrodynamic shear stresses

AU - Borejdo, J.

AU - Muhlrad, A.

AU - Leibovich, S. J.

AU - Oplatka, A.

PY - 1981/1/30

Y1 - 1981/1/30

N2 - In the absence of Ca2+ G-actin can be polymerized by the application of shear stress in low ionic strength buffer. When G-actin in low ionic strength buffer containing EGTA was sheared for predetermined times under different velocity gradients, viscosity attained a maximal value, comparable to that obtained by seeding with F-actin nuclei, at a velocity gradient of 3000 s-1 after about one hour. Such fiow-polymerized actin was indistinguishable from KCl-polymerized actin. Under similar conditions, EDTA which can bind both Ca2+ and Mg2+, gave a smaller effect than the Ca2+-chelating agent EGTA which binds Mg2+ weakly. When an Mg2+ salt was added to EDTA- or EGTA-containing buffer to give a free Mg2+ concentration of a few micromoles/liter, flow induced polymerization was significantly enhanced. It appears that occupancy of only a small fraction of the high affinity binding sites by Ca2+ prevents flow-polymerization while Mg2+ may enhance this type of polymerization by replacing Ca2+. We speculate that the shear stress induces polymerization by promoting nucleation and that Ca2+ bound to the high affinity divalent cation binding site inhibits formation of the nuclei.

AB - In the absence of Ca2+ G-actin can be polymerized by the application of shear stress in low ionic strength buffer. When G-actin in low ionic strength buffer containing EGTA was sheared for predetermined times under different velocity gradients, viscosity attained a maximal value, comparable to that obtained by seeding with F-actin nuclei, at a velocity gradient of 3000 s-1 after about one hour. Such fiow-polymerized actin was indistinguishable from KCl-polymerized actin. Under similar conditions, EDTA which can bind both Ca2+ and Mg2+, gave a smaller effect than the Ca2+-chelating agent EGTA which binds Mg2+ weakly. When an Mg2+ salt was added to EDTA- or EGTA-containing buffer to give a free Mg2+ concentration of a few micromoles/liter, flow induced polymerization was significantly enhanced. It appears that occupancy of only a small fraction of the high affinity binding sites by Ca2+ prevents flow-polymerization while Mg2+ may enhance this type of polymerization by replacing Ca2+. We speculate that the shear stress induces polymerization by promoting nucleation and that Ca2+ bound to the high affinity divalent cation binding site inhibits formation of the nuclei.

KW - G-Actin

KW - Polymerization

KW - Shear stress

UR - http://www.scopus.com/inward/record.url?scp=0019890910&partnerID=8YFLogxK

U2 - 10.1016/0005-2795(81)90072-6

DO - 10.1016/0005-2795(81)90072-6

M3 - Article

C2 - 6783112

AN - SCOPUS:0019890910

VL - 667

SP - 118

EP - 131

JO - BBA - Protein Structure

JF - BBA - Protein Structure

SN - 0005-2795

IS - 1

ER -