Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Discovery in parasite movement may offer insights into malaria

24.05.2004


University of North Carolina at Chapel Hill scientists have discovered a protein in the cell wall of parasites that’s crucial to the molecular mechanism allowing them to move between cells, survive and cause disease.



The discovery was made in Toxoplasma gondii, an organism that can cause blindness and brain damage in people with an impaired immune system and can cause severe disease in first trimester fetuses. In addition, the organism is used as a model experimental system for studying the closely related mosquito-borne malaria parasite Plasmodium.

"The way these organisms move and the way their movement is controlled is absolutely critical to their ability to cause disease," said Dr. Con Beckers, associate professor of cell and developmental biology at UNC’s School of Medicine.


"Movement is necessary for these parasites to spread within the host animal, it is necessary for their ability to enter host cells, and movement is also necessary for parasites to escape from the host cell, to swim off and find a new cell."

A report of the research appeared in the May 10 issue of the Journal of Cell Biology. Co-authors are Beckers, Elizabeth Gaskins, Nicollete DeVore and Tara Mann, all of UNC; and Stacey Gilk and Gary Ward, of the University of Vermont.

The research will have relevance to malaria and a variety of related pathogens including Cryptosporidium, which causes disease in the elderly and in people with AIDS.

Protozoan parasites in the phylum that includes Toxoplasma and Plasmodium normally lack external structures such as hairlike cilia, pseudopodia and whiplike flagella for movement, the report said. Instead, their movement is through a unique process called gliding motility - a circular and forward twisting movement - that remains poorly defined, the scientists said.

In an attempt to understand the parasite’s movement machinery, the study team began by characterizing the protein composition of the organism’s cell wall. Among the many proteins they found was one that was novel, Beckers said.

"This particular protein, TgGAP50, was probably the major discovery here, an integral membrane protein, a protein embedded in the membrane of the parasite."

The researchers found that TgGAP50 associates with another major protein expressed by the parasite TgMyoA. Myosins are known to be involved in motility. For example, they are present in muscle, where, in combination with the protein actin, they form the thick filaments of muscle.

"This new protein is embedded in the inner membrane complex of the parasite, where it’s directly involved in anchoring myosin to the membrane," Beckers said. "This is, in fact, only the second example of a protein that directly does this."

Thus, the new protein is a specific membrane receptor for what the researchers say is a "myosin motor."

Toxoplasma motility may be a result of the myosin moving along the length of actin filaments in the parasite, Beckers said. Alternatively, it may be caused by the myosin holding onto the end of a growing actin filament. Either way, the myosin molecule needs to be anchored in the parasite for movement to occur.

"If the myosin is not anchored anywhere, its movement with respect to an actin filament will not result in parasite motility," Beckers said. "As an analogy, if you’re sitting in a small boat and throw a rope out to the dock and someone’s there to hold it, you can pull yourself toward that person. But if no one is there, all you’ll do is pull the rope and no net movement will occur."

Thus, apart from having identified a complex of proteins containing a major myosin in Toxoplasma, the new study has "gone one step further because we identified a protein that actually anchors this myosin-containing complex in the membrane. And this protein is absolutely critical to parasite motility," Beckers said.

"Since motility is so central to survival of this class of parasites, it’s incredibly important that we understand the basic elements of their motile apparatus and how the different components are controlled by the parasite," Beckers said.

"Toxoplasma is motile outside the host cell, not inside it. If we understood parasite motility, we may find a way through some interference with its control mechanisms to convince the organism that it’s actually inside the cell. And if we did that you’d have a non-motile parasite that would not survive to cause disease."


Funding for the research came from the National Institute of Allergy and Infectious Diseases and the Burroughs-Wellcome Fund.

Note: Contact Beckers at 919-966-1464 or cbeckers@med.unc.edu.
School of Medicine contact: Les Lang, 919-843-9687 or llang@med.unc.edu

Leslie H. Lang | EurekAlert!
Further information:
http://www.med.unc.edu/

More articles from Life Sciences:

nachricht Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>