Format

Send to

Choose Destination
Biophys J. 2019 Jun 4;116(11):2172-2180. doi: 10.1016/j.bpj.2019.02.034. Epub 2019 Apr 30.

DNA Conformational Changes Play a Force-Generating Role during Bacteriophage Genome Packaging.

Author information

1
Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania.
2
Department of Biological Sciences, Columbia University, New York, New York.
3
Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania.
4
Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: sharvey7@icloud.com.

Abstract

Motors that move DNA, or that move along DNA, play essential roles in DNA replication, transcription, recombination, and chromosome segregation. The mechanisms by which these DNA translocases operate remain largely unknown. Some double-stranded DNA (dsDNA) viruses use an ATP-dependent motor to drive DNA into preformed capsids. These include several human pathogens as well as dsDNA bacteriophages-viruses that infect bacteria. We previously proposed that DNA is not a passive substrate of bacteriophage packaging motors but is instead an active component of the machinery. We carried out computational studies on dsDNA in the channels of viral portal proteins, and they reveal DNA conformational changes consistent with that hypothesis. dsDNA becomes longer ("stretched") in regions of high negative electrostatic potential and shorter ("scrunched") in regions of high positive potential. These results suggest a mechanism that electrostatically couples the energy released by ATP hydrolysis to DNA translocation: The chemical cycle of ATP binding, hydrolysis, and product release drives a cycle of protein conformational changes. This produces changes in the electrostatic potential in the channel through the portal, and these drive cyclic changes in the length of dsDNA as the phosphate groups respond to the protein's electrostatic potential. The DNA motions are captured by a coordinated protein-DNA grip-and-release cycle to produce DNA translocation. In short, the ATPase, portal, and dsDNA work synergistically to promote genome packaging.

PMID:
31103227
PMCID:
PMC6554637
[Available on 2020-06-04]
DOI:
10.1016/j.bpj.2019.02.034

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center