Navigation Links
Basis for DNA ejection from single phage particles

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.

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


'"/>

Source:Cell Press


Related biology news :

1. Fibril Shape Is The Basis Of Prion Strains And Cross-species Prion Infection
2. New type of rejection blocker protects kidneys after transplant
3. Simple sea sponge helps scientists understand tissue rejection
4. Researchers identify genes associated with lung transplant rejection
5. Carnegie Mellon develops non-invasive technique to detect transplant rejection at cellular level
6. Combination therapy with a monocloncal antibody and a vaccine leads to tumor rejection
7. Proteins may predict lung transplant rejection
8. Opposing fat metabolism pathways triggered by a single gene
9. Ancient DNA confirms single origin of Malagasy primates
10. No single gene for ageing
11. Natural selection at single gene demonstrated
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:1/20/2016)... --  MedNet Solutions , an innovative SaaS-based eClinical technology ... is pleased to announce the attainment of record-setting corporate ... of the company,s laser focus on (and growing international ... comprehensive, easy-to-use and highly affordable cloud-based technology platform. ... growth achievements in 2015 include: , Record ...
(Date:1/18/2016)... 2016  Extenua Inc., a pioneering developer of ... and access of ubiquitous on-premise and cloud storage, today ... Cyber.  ... C4ISR and Cyber initiatives in support of National ... technology solutions," said Steve Visconti , Extenua ...
(Date:1/13/2016)... , January 13, 2016 ... published a new market report titled - Biometric Sensors Market ... Forecast, 2015 - 2023. According to the report, the global biometric ... is anticipated to reach US$1,625.8 mn by 2023, expanding ... In terms of volume, the biometric sensors market is ...
Breaking Biology News(10 mins):
(Date:2/4/2016)... -- ContraVir Pharmaceuticals, Inc. (NASDAQ: CTRV ), a ... targeted antiviral therapies, announced today that it will present ... held February 8-9, 2016, at the Waldorf Astoria New ... Healthcare Conference, taking place in New York ... Sapirstein , Chief Executive Officer of ContraVir, will provide ...
(Date:2/4/2016)... February 4, 2016 Strasbourg, France ... Inc. --> Strasbourg, France , to ... PharmaVentures is pleased to announce that it acted as ... manufacturing unit in Strasbourg, France , to ... --> --> Transgene (Euronext: TNG), a ...
(Date:2/3/2016)...  With the growing need for better therapeutics, ... therapies such as monoclonal antibodies, recombinant protein therapeutics ... indications are in high demand. Conventionally expression systems ... production of these therapeutics. However, due to issues ... novel approaches and novel expression systems are currently ...
(Date:2/3/2016)... ... February 03, 2016 , ... ... new office dedicated to the North American healthcare market. , Aerocom Healthcare, LLC ... facilities. The company will provide new pneumatic tube systems or expand existing ...
Breaking Biology Technology: