Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Protein helps parasite survive in host cells

29.12.2010
Researchers at Washington University School of Medicine in St. Louis have learned why changes in a single gene, ROP18, contribute substantially to dangerous forms of the parasite Toxoplasma gondii. The answer has likely moved science a step closer to new ways to beat Toxoplasma and many other parasites.

In a study published in Cell Host & Microbe, scientists show that the ROP18 protein disables host cell proteins that would otherwise pop a protective bubble the parasite makes for itself. The parasite puts the bubble on like a spacesuit by forming a membrane around itself when it enters host cells. This protects it from the hostile environment inside the cell, which would otherwise kill it.

“If we can find therapies that block ROP18 and other parasite proteins like it, that could give the host the upper hand in the battle against infection,” says first author Sarah Fentress, a graduate student in the laboratory of L. David Sibley, PhD, professor of molecular microbiology.

Infection with Toxoplasma, or toxoplasmosis, is most familiar to the general public from the recommendation that pregnant women avoid changing cat litter. Cats are commonly infected with the parasite, as are some livestock and wildlife.

“The exact role of ROP18 and related proteins in human disease remains to be studied,” says Sibley. “But mice are natural hosts of Toxoplasma, so studies in laboratory mice are relevant to the spread of infection.”

Epidemiologists estimate that as many as one in every four humans is infected with Toxoplasma. Infections typically cause serious disease only in patients with weakened immune systems. In some rare cases, though, infection in patients with healthy immune systems leads to serious eye or central nervous system disease, or congenital defects or death in the fetuses of pregnant women.

In the new study, Fentress showed that the ROP18 protein binds to a class of host proteins known as immunity-related GTPases. Tests in cell cultures and animal models showed that this binding leads to a reaction that disables the GTPases, which normally would rupture the parasite's protective membrane.

“With one exception, humans don’t have the same family of immunity-related GTPases,” Fentress notes. “But we do have a similar group of immune recognition proteins called guanylate-binding proteins, and we are currently testing to see if ROP18 deactivates these proteins in human cells in a similar manner.”

The findings could be applicable to other parasites and pathogens. Toxoplasmosis belongs to a family of parasites that includes the parasite Plasmodium, which causes malaria. All surround themselves with protective membranes when they enter host cells.

“Plasmodium doesn’t make ROP18, but it does secrete related proteins called FIKK,” says Fentress. “It’s possible they also act to thwart host defense mechanisms like GTPases and guanylate-binding proteins.”

Fentress SJ, Behnke MS, Dunay Ir, Mashayekhi M, Rommereim LM, Fox BA, Bzik DJ, Taylor GA, Turk BE, Lichti CF, Townsend RR, Qiu W, Hui R, Beatty WL, Sibley LD. Phosphorylation of immunity-related GTPases by a Toxoplasma gondii-secreted kinase promotes macrophage survival and virulence. Cell Host & Microbe, Dec. 22, 2010.

This research was supported by the National Institutes of Health and the Veteran’s Administration.

Washington University School of Medicine’s 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.

Michael C. Purdy | EurekAlert!
Further information:
http://www.wustl.edu
http://news.wustl.edu/news/Pages/21673.aspx

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 >>>