Testing a structural model for viral DNA packaging motor function by optical tweezers measurements, site directed mutagenesis, and molecular dynamics calculations

Nicholas A. Keller; Amy Davenport Migliori; Gaurav Arya; Venigalla B. Rao; Douglas E. Smith

doi:10.1117/12.2027158

12 September 2013 Testing a structural model for viral DNA packaging motor function by optical tweezers measurements, site directed mutagenesis, and molecular dynamics calculations

Nicholas A. Keller, Amy Davenport Migliori, Gaurav Arya, Venigalla B. Rao, Douglas E. Smith

Author Affiliations +

Proceedings Volume 8810, Optical Trapping and Optical Micromanipulation X; 881032 (2013) https://doi.org/10.1117/12.2027158
Event: SPIE NanoScience + Engineering, 2013, San Diego, California, United States

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.

Citation Download Citation

Nicholas A. Keller, Amy Davenport Migliori, Gaurav Arya, Venigalla B. Rao, and Douglas E. Smith "Testing a structural model for viral DNA packaging motor function by optical tweezers measurements, site directed mutagenesis, and molecular dynamics calculations", Proc. SPIE 8810, Optical Trapping and Optical Micromanipulation X, 881032 (12 September 2013); https://doi.org/10.1117/12.2027158

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