Ion-Dependent Dynamics of DNA Ejections for Bacteriophage λ
- Creators
- Wu, David
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Van Valen, David
- Hu, Qicong
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Phillips, Rob
Abstract
We studied the control parameters that govern the dynamics of in vitro DNA ejection in bacteriophage λ. Previous work demonstrated that bacteriophage DNA is highly pressurized, and this pressure has been hypothesized to help drive DNA ejection. Ions influence this process by screening charges on DNA; however, a systematic variation of salt concentrations to explore these effects has not been undertaken. To study the nature of the forces driving DNA ejection, we performed in vitro measurements of DNA ejection in bulk and at the single-phage level. We present measurements on the dynamics of ejection and on the self-repulsion force driving ejection. We examine the role of ion concentration and identity in both measurements, and show that the charge of counterions is an important control parameter. These measurements show that the mobility of ejecting DNA is independent of ionic concentrations for a given amount of DNA in the capsid. We also present evidence that phage DNA forms loops during ejection, and confirm that this effect occurs using optical tweezers.
Additional Information
© 2010 Biophysical Society. Published by Elsevier. Received 1 March 2010; accepted 9 June 2010. Editor: Laura Finzi.. Available online 17 August 2010. The authors thank the members of the physiology course at the Marine Biology Laboratory in Woods Hole, MA (Nicolas Chiaruttini, Paul Grayson, Zenan Chang, Alexander Grosberg, Ian Molineux, Michael Rubinstein, Virgile Viasnoff, William Gelbart, and Charles Knobler), and members of the Phillips laboratory. D.W. and D.V.V. were supported by a National Institutes of Health (NIH) Medical Scientist Training Program Fellowship. D.V.V. was supported by a Yaser Abu-Mostafa Hertz Fellowship and an NIH Director's Pioneer Award. R.P., D.W., and D.V.V. were supported by National Science Foundation grant No. 0758343 and an NIH Pioneer Award. Q.H. was supported by a predoctoral fellowship (BC083077) from the Department of Defense Breast Cancer Research Program.Attached Files
Supplemental Material - mmc1.pdf
Supplemental Material - mmc2.avi
Files
Additional details
- PMCID
- PMC2920739
- Eprint ID
- 19796
- Resolver ID
- CaltechAUTHORS:20100907-101147251
- NIH
- Yaser Abu-Mostafa Hertz Fellowship
- 0758343
- NSF
- BC083077
- Department of Defense Breast Cancer Research Program
- Created
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2010-09-08Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field