Atomistic and Coarse-grained Analysis of Double Spectrin Repeat Units: The Molecular Origins of Flexibility

Dina T. Mirijanian, Jhih-Wei Chu, Gary S. Ayton, Gregory A. Voth*

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Spectrin is an ubiquitous protein in metazoan cells, and its flexibility is one of the keys to maintaining cellular structure and organization. Both α-spectrin and β-spectrin polypeptides consist primarily of triple coiled-coil modular repeat units, and two important factors that determine spectrin flexibility are the bending flexibility between two consecutive repeat units and the conformational flexibility of individual repeat units. Atomistic molecular dynamics (MD) simulations are used here to study double spectrin repeat units (DSRUs) from the human erythrocyte β-spectrin (HEβ89) and the chicken brain α-spectrin (CBα1617). From the results of MD simulations, a highly conserved Trp residue in the A-helix of most repeat units that has been suggested to be important in conferring stability to the coiled-coil structures is found not to have a significant effect on the conformational flexibility of individual repeat units. Characterization of the bending flexibility for two consecutive repeats of spectrin via atomistic simulations and coarse-grained (CG) modeling indicate that the bending flexibility is governed by the interactions between the AB-loop of the first repeat unit, the BC-loop of the second repeat unit and the linker region. Specifically, interactions between residues in these regions can lead to a strong directionality in the bending behavior of two repeat units. The biological implications of these finding are discussed.

Original languageEnglish
Pages (from-to)523-534
Number of pages12
JournalJournal of Molecular Biology
Volume365
Issue number2
DOIs
StatePublished - 12 Jan 2007

Keywords

  • cytoskeleton
  • erythrocyte
  • flexibility
  • molecular dynamics
  • spectrin family

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