Continuous Allosteric Regulation of a Viral Packaging Motor by a Sensor that Detects the Density and Conformation of Packaged DNA

We report evidence for an unconventional type of allosteric regulation of a biomotor. We show that the genome-packaging motor of phage ϕ29 is regulated by a sensor that detects the density and conformation of the DNA packaged inside the viral capsid, and slows the motor by a mechanism distinct from...

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Bibliographic Details
Published in:Biophysical journal 2015-01, Vol.108 (2), p.315-324
Main Authors: Berndsen, Zachary T., Keller, Nicholas, Smith, Douglas E.
Format: Article
Language:English
Subjects:
Adenosine triphosphatase
Adenosine Triphosphate - metabolism
Allosteric Regulation
Bacillus Phages - chemistry
Bacillus Phages - metabolism
Bacillus Phages - physiology
Deoxyribonucleic acid
DNA
DNA Packaging
DNA, Viral - chemistry
Genomes
Molecular Machines, Motors, and Nanoscale Biophysics
Packaging
Phage h29
Protein Binding
Viral Proteins - chemistry
Viral Proteins - metabolism
Virus Assembly
Viruses
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Summary:We report evidence for an unconventional type of allosteric regulation of a biomotor. We show that the genome-packaging motor of phage ϕ29 is regulated by a sensor that detects the density and conformation of the DNA packaged inside the viral capsid, and slows the motor by a mechanism distinct from the effect of a direct load force on the motor. Specifically, we show that motor-ATP interactions are regulated by a signal that is propagated allosterically from inside the viral shell to the motor mounted on the outside. This signal continuously regulates the motor speed and pausing in response to changes in either density or conformation of the packaged DNA, and slows the motor before the buildup of large forces resisting DNA confinement. Analysis of motor slipping reveals that the force resisting packaging remains low (
ISSN:0006-3495
1542-0086
DOI:10.1016/j.bpj.2014.11.3469