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Real-time imaging of DNA ejection from single phage particles
Stéphanie Mangenot1, Marion Hochrein, Joachim Rädler
1Ludwig Maximilian Universität, Sektion Physik, Geschwister-Scholl-Platz 1, D-80539 München, Germany.
Current Biology : CB
|March 9, 2005
Summary
Phage T5 injects its DNA into E. coli in a stepwise manner, not all at once. This DNA ejection occurs rapidly, reaching speeds of 75,000 base pairs per second.
Area of Science:
- Microbiology
- Molecular Biology
- Biophysics
Background:
- Tailed double-stranded DNA (dsDNA) phages initiate infection by injecting their genome into a host cell.
- The precise mechanism and driving force behind viral genome transport remain incompletely understood.
- Internal capsid pressure from DNA packaging is a proposed driver for DNA ejection.
Purpose of the Study:
- To investigate the dynamics of DNA ejection from single T5 phages in real-time.
- To determine if DNA release is an instantaneous event or a gradual process.
- To quantify the rate of DNA ejection during phage infection.
Main Methods:
- Utilized fluorescence microscopy to observe DNA ejection from single T5 phages.
- Adsorbed phages onto a microfluidic cell for controlled observation.
- Fluorescently stained ejected DNA and measured its length under hydrodynamic flow.
Main Results:
- DNA release from T5 phage is not an all-or-none process but occurs stepwise.
- The rate of stepwise DNA ejection can reach up to 75,000 base pairs per second.
- Observed dynamics provide insights into the energy requirements for genome transfer.
Conclusions:
- The findings challenge the notion of instantaneous DNA ejection.
- Stepwise DNA ejection offers a more nuanced understanding of viral genome delivery.
- The study discusses the implications of these findings for in vivo phage infection processes.