Order-Order Transition of Size-mismatched Ions on F-actin Polyelectrolytes

ORAL

Abstract

Multivalent ions induce condensation of like-charged F-actin polyelectrolytes into close-packed bundles, in which multivalent ions organize into 1-D density waves. We examine the condensation behavior of anionic F-actin using multivalent cations with a large size mismatch, Ba$^{2+}$ and lysozyme(+9), a small globular protein (2.5nm x 2.5nm x 4.5nm). An unexpected first-order phase transition on the F-actin surface between a Ba$^{2+}$ counterion charge density wave state and 1-D close-packed lysozyme chains is found as the lysozyme-actin ratio is varied. By comparing wild-type lysozyme with genetically-engineered lysozyme with reduced charge, we show that this transition shifts with the actin-lysozyme isoelectric point.

Authors

  • Robert Coridan

    • Department of Physics, University of Illinois at Urbana-Champaign
    • Department of Physics, University of Illinois, Urbana-Champaign

  • Lori K. Sanders

    • Department of Materials Science \& Engineering, University of Illinois at Urbana-Champaign

  • Wujing Xian

    • Department of Materials Science \& Engineering, Department of Bioengineering, University of Illinois, Urbana-Champaign

  • Brian W. Matthews

    • Institute of Molecular Biology, University of Oregon at Eugene

  • Gerard C. L. Wong

    • Dept. of Materials Science and Engineering, Physics and Bioengineering, University of Illinois at Urbana-Champaign
    • Department of Materials Science \& Engineering, Department of Physics, Department of Bioengineering, University of Illinois at Urbana-Champaign
    • Department of Materials Science and Engineering, Department of Physics, Department of Bioengineering, University of Illinois at Urbana Champaign
    • University of Illinois at Urbana-Champaign
    • Department of Materials Science \& Engineering, Department of Physics, Department of Bioengineering, University of Illinois