Featured Research

from universities, journals, and other organizations

Basis For DNA Ejection From Single Phage Particles

Date:
March 12, 2005
Source:
Cell Press
Summary:
Studying phage, a primitive class of virus that infects bacteria by injecting its genomic DNA into host cells, researchers have gained insight into the driving force behind this poorly understood injection process, which has been proposed in the past to occur through the release of pressure accumulated within the viral particle itself.

Studying phage, a primitive class of virus that infects bacteria by injecting its genomic DNA into host cells, researchers have gained insight into the driving force behind this poorly understood injection process, which has been proposed in the past to occur through the release of pressure accumulated within the viral particle itself.

Related Articles


Almost all phages (also known as bacteriophages) are formed of a capsid structure, or head, in which the viral genome is packaged during morphogenesis, and a tail structure that ensures the attachment of the phage to the host bacteria. A common feature of phages is that during infection, only their genome is transferred to the bacterial host's cytoplasm, whereas the capsid and tail remain bound to the cell surface. This situation is very different from that found in most eukaryotic viruses, including those that infect humans, in that the envelope of these viruses fuses with the host plasma membrane so that the genome is delivered without directly contacting the membrane.

Phage nucleic acid transport poses a fascinating biophysical problem: Transport is unidirectional and linear; it concerns a unique molecule the size of which may represent 50 times that of the bacterium. The driving force for DNA transport is still poorly defined. It was hypothesized that the internal pressure built during packaging of the DNA in the phage capsid was responsible for DNA ejection. This pressure results from the condensation of the DNA during morphogenesis – for example, another group recently showed that the pressure at the final stage of encapsulation for a particular bacteriophage reached a value of 60 atomospheres, which is close to ten times the pressure inside a bottle of champagne. In the new work reported this week, researchers have evaluated whether the energy thus stored is sufficient to permit phage DNA ejection, or only to initiate that process.

The researchers used fluorescently labeled phage DNA to investigate in real time (and with a resolution time of 750 milliseconds) the dynamics of DNA ejection from single phages. The ejected DNA was measured at different stages of the ejection process after being stretched by applied hydrodynamic flow. The study demonstrated that DNA release is not an all-or-none process, but rather is unexpectedly complex. DNA release occurred at a very high rate, reaching 75,000 base pairs of DNA/sec, but in a stepwise fashion. Pausing times were observed during ejection, and ejection was transiently arrested at definite positions of the genome in close proximity to genetically defined physical interruptions in the DNA. The authors discuss the relevance of this stepwise ejection to the transfer of phage DNA in vivo.

###

Stéphanie Mangenot, Marion Hochrein, Joachim Rädler, and Lucienne Letellier: "Real-Time Imaging of DNA Ejection from Single Phage Particles"

The other members of the research team include Stéphanie Mangenot of the Laboratoire de Physique des Solides, UMR CNRS at Université Paris Sud; Marion Hochrein and Joachim Rädler of Ludwig Maximilian Universität; and Lucienne Letellier of the Institut de Biochimie et Biophysique Moléculaire et Cellulaire, UMR, CNRS at Université Paris Sud. This project was supported in part by the Centre National de la Recherche Scientifique program "Dynamique et Réactivité des Assemblages Biologiques" and by SFB 563 "Bioorganic Functional Systems on Solids."

Publishing in Current Biology, Volume 15, Number 5, March 8, 2005, pages 430-435. http://www.current-biology.com


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Cite This Page:

Cell Press. "Basis For DNA Ejection From Single Phage Particles." ScienceDaily. ScienceDaily, 12 March 2005. <www.sciencedaily.com/releases/2005/03/050310103113.htm>.
Cell Press. (2005, March 12). Basis For DNA Ejection From Single Phage Particles. ScienceDaily. Retrieved April 2, 2015 from www.sciencedaily.com/releases/2005/03/050310103113.htm
Cell Press. "Basis For DNA Ejection From Single Phage Particles." ScienceDaily. www.sciencedaily.com/releases/2005/03/050310103113.htm (accessed April 2, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Thursday, April 2, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Wound-Healing Laser Soon to Be a Reality Israeli Scientist

Wound-Healing Laser Soon to Be a Reality Israeli Scientist

Reuters - Innovations Video Online (Apr. 1, 2015) — Israeli scientists says laser bonding of tissue allows much faster healing and less scarring. Amy Pollock has more. Video provided by Reuters
Powered by NewsLook.com
Liberia Sees Resurgence of Drug Trafficking as Ebola Wanes

Liberia Sees Resurgence of Drug Trafficking as Ebola Wanes

AFP (Apr. 1, 2015) — The governments of Liberia and Sierra Leone have been busy fighting the menace created by the deadly Ebola virus, but illicit drug lords have taken advantage of the situation to advance the drug trade. Duration: 01:12 Video provided by AFP
Powered by NewsLook.com
Stigma Stalks India's Leprosy Sufferers as Disease Returns

Stigma Stalks India's Leprosy Sufferers as Disease Returns

AFP (Apr. 1, 2015) — The Indian government declared victory over leprosy in 2005, but the disease is making a comeback in some parts of the country, with more than a hundred thousand lepers still living in colonies, shunned from society. Duration: 02:41 Video provided by AFP
Powered by NewsLook.com
7-Year-Old Girl Gets 3-D Printed 'robohand'

7-Year-Old Girl Gets 3-D Printed 'robohand'

AP (Mar. 31, 2015) — Although she never had much interest in prosthetic limbs before, Faith Lennox couldn&apos;t wait to slip on her new robohand. The 7-year-old, who lost part of her left arm when she was a baby, grabbed it as soon as it came off a 3-D printer. (March 31) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins