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Portal Stability Controls Dynamics of DNA Ejection from Phage

Freeman, Krista G.; Behrens, Manja A. LU ; Streletzky, Kiril A.; Olsson, Ulf LU and Evilevitch, Alex LU (2016) In Journal of Physical Chemistry B 120(26). p.6421-6429
Abstract

Through a unique combination of time-resolved single-molecule (cryo-TEM) and bulk measurements (light scattering and small-angle X-ray scattering), we provide a detailed study of the dynamics of stochastic DNA ejection events from phage λ. We reveal that both binding with the specific phage receptor, LamB, and thermo-mechanical destabilization of the portal vertex on the capsid are required for initiation of ejection of the pressurized λ-DNA from the phage. Specifically, we found that a measurable activation energy barrier for initiation of DNA ejection with LamB present, Ea = (1.2 ± 0.1) × 10-19 J/phage (corresponding to ∼28 kTbody/phage at Tbody = 37 °C), results in 15 times increased rate... (More)

Through a unique combination of time-resolved single-molecule (cryo-TEM) and bulk measurements (light scattering and small-angle X-ray scattering), we provide a detailed study of the dynamics of stochastic DNA ejection events from phage λ. We reveal that both binding with the specific phage receptor, LamB, and thermo-mechanical destabilization of the portal vertex on the capsid are required for initiation of ejection of the pressurized λ-DNA from the phage. Specifically, we found that a measurable activation energy barrier for initiation of DNA ejection with LamB present, Ea = (1.2 ± 0.1) × 10-19 J/phage (corresponding to ∼28 kTbody/phage at Tbody = 37 °C), results in 15 times increased rate of ejection event dynamics when the temperature is raised from 15 to 45 °C (7.5 min versus 30 s average lag time for initiation of ejection). This suggests that phages have a double fail-safe mechanism for ejection - in addition to receptor binding, phage must also overcome (through thermal energy and internal DNA pressure) an energy barrier for DNA ejection. This energy barrier ensures that viral genome ejection into cells occurs with high efficiency only when the temperature conditions are favorable for genome replication. At lower suboptimal temperatures, the infectious phage titer is preserved over much longer times, since DNA ejection dynamics is strongly inhibited even in the presence of solubilized receptor or susceptible cells. This work also establishes a light scattering based approach to investigate the influence of external solution conditions, mimicking those of the bacterial cytoplasm, on the stability of the viral capsid portal, which is directly linked to dynamics of virion deactivation.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry B
volume
120
issue
26
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • scopus:84978076667
  • wos:000379457200071
ISSN
1520-6106
DOI
10.1021/acs.jpcb.6b04172
language
English
LU publication?
yes
id
851b2cce-802f-4cee-ba87-a41dd03eb066
date added to LUP
2017-01-12 14:20:11
date last changed
2017-09-18 11:36:32
@article{851b2cce-802f-4cee-ba87-a41dd03eb066,
  abstract     = {<p>Through a unique combination of time-resolved single-molecule (cryo-TEM) and bulk measurements (light scattering and small-angle X-ray scattering), we provide a detailed study of the dynamics of stochastic DNA ejection events from phage λ. We reveal that both binding with the specific phage receptor, LamB, and thermo-mechanical destabilization of the portal vertex on the capsid are required for initiation of ejection of the pressurized λ-DNA from the phage. Specifically, we found that a measurable activation energy barrier for initiation of DNA ejection with LamB present, E<sub>a</sub> = (1.2 ± 0.1) × 10<sup>-19</sup> J/phage (corresponding to ∼28 kT<sub>body</sub>/phage at T<sub>body</sub> = 37 °C), results in 15 times increased rate of ejection event dynamics when the temperature is raised from 15 to 45 °C (7.5 min versus 30 s average lag time for initiation of ejection). This suggests that phages have a double fail-safe mechanism for ejection - in addition to receptor binding, phage must also overcome (through thermal energy and internal DNA pressure) an energy barrier for DNA ejection. This energy barrier ensures that viral genome ejection into cells occurs with high efficiency only when the temperature conditions are favorable for genome replication. At lower suboptimal temperatures, the infectious phage titer is preserved over much longer times, since DNA ejection dynamics is strongly inhibited even in the presence of solubilized receptor or susceptible cells. This work also establishes a light scattering based approach to investigate the influence of external solution conditions, mimicking those of the bacterial cytoplasm, on the stability of the viral capsid portal, which is directly linked to dynamics of virion deactivation.</p>},
  author       = {Freeman, Krista G. and Behrens, Manja A. and Streletzky, Kiril A. and Olsson, Ulf and Evilevitch, Alex},
  issn         = {1520-6106},
  language     = {eng},
  month        = {07},
  number       = {26},
  pages        = {6421--6429},
  publisher    = {The American Chemical Society},
  series       = {Journal of Physical Chemistry B},
  title        = {Portal Stability Controls Dynamics of DNA Ejection from Phage},
  url          = {http://dx.doi.org/10.1021/acs.jpcb.6b04172},
  volume       = {120},
  year         = {2016},
}