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Proceedings Paper

Testing a structural model for viral DNA packaging motor function by optical tweezers measurements, site directed mutagenesis, and molecular dynamics calculations
Author(s): Nicholas A. Keller; Amy Davenport Migliori; Gaurav Arya; Venigalla B. Rao; Douglas E. Smith
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Paper Abstract

Many double-stranded DNA viruses employ a molecular motor to package DNA into preformed capsid shells. Based on structures of phage T4 motor proteins determined by X-ray crystallography and cryo-electron microscopy, Rao, Rossmann and coworkers recently proposed a structural model for motor function. They proposed that DNA is ratcheted by a large conformational change driven by electrostatic interactions between charged residues at an interface between two globular domains of the motor protein. We have conducted experiments to test this model by studying the effect on packaging under applied load of site-directed changes altering these residues. We observe significant impairment of packaging activity including reductions in packaging rate, percent time packaging, and time active under high load. We show that these measured impairments correlate well with alterations in free energies associated with the conformational change predicted by molecular dynamics simulations.

Paper Details

Date Published: 12 September 2013
PDF: 6 pages
Proc. SPIE 8810, Optical Trapping and Optical Micromanipulation X, 881032 (12 September 2013); doi: 10.1117/12.2027158
Show Author Affiliations
Nicholas A. Keller, Univ. of California, San Diego (United States)
Amy Davenport Migliori, Univ. of California, San Diego (United States)
Gaurav Arya, Univ. of California, San Diego (United States)
Venigalla B. Rao, Catholic Univ. of America (United States)
Douglas E. Smith, Univ. of California, San Diego (United States)

Published in SPIE Proceedings Vol. 8810:
Optical Trapping and Optical Micromanipulation X
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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