title: Finding of widespread viral and bacterial revolution dsDNA translocation motors distinct from rotation motors by channel chirality and size.
abstract: BACKGROUND
  Double-stranded DNA translocation is ubiquitous in living systems. Cell mitosis, bacterial binary fission, DNA replication or repair, homologous recombination, Holliday junction resolution, viral genome packaging and cell entry all involve biomotor-driven dsDNA translocation. Previously, biomotors have been primarily classified into linear and rotational motors. We recently discovered a third class of dsDNA translocation motors in Phi29 utilizing revolution mechanism without rotation. Analogically, the Earth rotates around its own axis every 24 hours, but revolves around the Sun every 365 days.
  
  
  RESULTS
  Single-channel DNA translocation conductance assay combined with structure inspections of motor channels on bacteriophages P22, SPP1, HK97, T7, T4, Phi29, and other dsDNA translocation motors such as bacterial FtsK and eukaryotic mimiviruses or vaccinia viruses showed that revolution motor is widespread. The force generation mechanism for revolution motors is elucidated. Revolution motors can be differentiated from rotation motors by their channel size and chirality. Crystal structure inspection revealed that revolution motors commonly exhibit channel diameters larger than 3 nm, while rotation motors that rotate around one of the two separated DNA strands feature a diameter smaller than 2 nm. Phi29 revolution motor translocated double- and tetra-stranded DNA that occupied 32% and 64% of the narrowest channel cross-section, respectively, evidencing that revolution motors exhibit channel diameters significantly wider than the dsDNA. Left-handed oriented channels found in revolution motors drive the right-handed dsDNA via anti-chiral interaction, while right-handed channels observed in rotation motors drive the right-handed dsDNA via parallel threads. Tethering both the motor and the dsDNA distal-end of the revolution motor does not block DNA packaging, indicating that no rotation is required for motors of dsDNA phages, while a small-angle left-handed twist of dsDNA that is aligned with the channel could occur due to the conformational change of the phage motor channels from a left-handed configuration for DNA entry to a right-handed configuration for DNA ejection for host cell infection.
  
  
  CONCLUSIONS
  The revolution motor is widespread among biological systems, and can be distinguished from rotation motors by channel size and chirality. The revolution mechanism renders dsDNA void of coiling and torque during translocation of the lengthy helical chromosome, thus resulting in more efficient motor energy conversion.
authors.affiliation: Nanobiotechnology Center, University of Kentucky, Lexington, KY, USA.|Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.|Markey Cancer Center, University of Kentucky, Lexington, KY, USA.
authors.forename: Gian Marco
authors.initials: GM
authors.lastname: De-Donatis
authors.affiliation: Nanobiotechnology Center, University of Kentucky, Lexington, KY, USA.|Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.|Markey Cancer Center, University of Kentucky, Lexington, KY, USA.
authors.forename: Zhengyi
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Nanobiotechnology Center, University of Kentucky, Lexington, KY, USA.|Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.|Markey Cancer Center, University of Kentucky, Lexington, KY, USA.
authors.forename: Shaoying
authors.initials: S
authors.lastname: Wang
authors.affiliation: Current address: Institute for Biomarker Research, Medical Diagnostic Laboratories, L.L.C., Hamilton, NJ 08690, USA.
authors.forename: Lisa P
authors.initials: LP
authors.lastname: Huang
authors.affiliation: Nanobiotechnology Center, University of Kentucky, Lexington, KY, USA.|Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.|Markey Cancer Center, University of Kentucky, Lexington, KY, USA.
authors.forename: Chad
authors.initials: C
authors.lastname: Schwartz
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Tsodikov
authors.affiliation: Nanobiotechnology Center, University of Kentucky, Lexington, KY, USA.|Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.|Markey Cancer Center, University of Kentucky, Lexington, KY, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Nanobiotechnology Center, University of Kentucky, Lexington, KY, USA.|Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.|Markey Cancer Center, University of Kentucky, Lexington, KY, USA.
authors.forename: Farzin
authors.initials: F
authors.lastname: Haque
authors.affiliation: Nanobiotechnology Center, University of Kentucky, Lexington, KY, USA.|Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA.|Markey Cancer Center, University of Kentucky, Lexington, KY, USA.|William Farish Endowed Chair in Nanobiotechnology, School of Pharmacy, University of Kentucky, 565 Biopharmaceutical Complex, 789 S. Limestone Street, Lexington, KY 40536, USA.
authors.forename: Peixuan
authors.initials: P
authors.lastname: Guo
keywords: Bacteriophage; DNA helicase; DNA translocase; DsDNA viruses; FtsK; Nanomotor; Phi29; RecA; Revolution force; Viral DNA packaging motor; Viral assembly