Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists identify motor that powers parasitic cell invasion

25.10.2002


The development of drugs to combat some of the world’s most serious parasitic diseases is a step nearer with the discovery of a widely-shared gene that helps parasites to invade host cells.



The new understanding of the gene’s role in the single-celled parasite Toxoplasma gondii gives scientists a target to block that could stop the parasite literally in its tracks.

In experiments reported today in the journal Science, researchers at Imperial College London and the University of Mannheim, Germany show that the motor powering Toxoplasma’s invasion of host cells is stopped when the parasite myosin A gene is disrupted.


Myosin A is present in all members of the Apicomplexa family of parasites, which includes Toxoplasma and Plasmodium falciparum, which cause Toxoplasmosis and malaria respectively.

Toxoplasma, mainly transmitted by consumption of contaminated meat or by cat faeces, chronically infects half the world’s population. The pathogen is a leading cause of neurological birth defects in children born to mothers who contract the disease during pregnancy and can cause fatal toxoplasmosis encephalitis in immunosuppressed patients.

Scientists hope that understanding the gene’s function will aid efforts to develop drugs that target and block the way Apicomplexa parasites penetrate host cells.

Unlike most viruses and bacteria that require host cell participation to attack cells and be engulfed, Apicomplexans actively penetrate cells.

They use a unique gliding motion powered by an actin-myosin system to rapidly spread throughout tissues in the host’s body and to invade cells.

"Our research demonstrates for the first time that parasite motility is powered by an unusual motor, which is essential for invading host cells," says research leader Dr Dominique Soldati from Imperial’s Department of Biological Sciences.

"The Apicomplexa family of parasites are all strictly dependent on an unusual gliding motion to get into cells. If the parasite can’t get in, it can’t establish an infection," she says.

Once the parasite docks with the host cell it sends out proteins that bind tightly to host cell receptors and create an indented pocket in the surface of the cell. The parasite’s myosin molecules then latch onto the newly formed protein-receptor complexes pulling the myosin along a skeleton of actin and into the cell.

"Myosin A is an extremely fast moving motor, comparable in speed to the myosin responsible for the contraction of muscle in humans. The motor propels the parasite at a speed of five micrometers per second, allowing it to penetrate host cells within 10 to 30 seconds.

"This rapid entry process is essential for Apicomplexan parasites to replicate safely, hidden from the immune system," says Dr Soldati.

Researchers established myosin A’s function by knocking out the gene in Toxoplasma gondii and observing the effects on its motility. They used time-lapse microscopy to score the percentage of parasites able to glide and perform normal forms of movement on coated glass slides.

"In optimum conditions freshly released parasites exhibit circular gliding, upright twirling and helical gliding. But with only partial gene function the parasites performed a reduced number or incomplete circles and at a lower speed. With the gene completely shut down the parasites were totally unable to move."

"Toxoplasma remains an important threat to human health with the continual spread of AIDS, while the malaria parasite kills more than 1 million children each year.

"A detailed understanding of the mechanism of host cell invasion by the Apicomplexans is an important and acute goal since such studies will lead to the identification of novel therapeutic targets, which are urgently needed," says Dr Soldati.

The work was funded by the Deutsche Forschungsgemeinschaft.

Judith H Moore | EurekAlert!
Further information:
http://www.imperial.ac.uk

More articles from Health and Medicine:

nachricht Inselspital: Fewer CT scans needed after cerebral bleeding
20.03.2019 | Universitätsspital Bern

nachricht Building blocks for new medications: the University of Graz is seeking a technology partner
19.03.2019 | Karl-Franzens-Universität Graz

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Solving the efficiency of Gram-negative bacteria

22.03.2019 | Life Sciences

Bacteria bide their time when antibiotics attack

22.03.2019 | Life Sciences

Open source software helps researchers extract key insights from huge sensor datasets

22.03.2019 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>