Researchers identify mechanism that helps bacteria avoid destruction in cells

Oct 10, 2009

Infectious diseases currently cause about one-third of all human deaths worldwide, more than all forms of cancer combined. Advances in cell biology and microbial genetics have greatly enhanced understanding of the cause and mechanisms of infectious diseases. Researchers from Thomas Jefferson University, the Pasteur Institute in Paris, and Yale University reported in PLoS ONE, a way in which intracellular pathogens exploit the biological attributes of their hosts in order to escape destruction.

Intracellular pathogens include Chlamydia, which causes infertility in women, and Legionella, which causes Legionnaire's disease. These pathogens are able to escape destruction and remain in the cells. Until now, it was unclear how they were able avoid the destruction process. The team of researchers, led by Fabienne Paumet, Ph.D., assistant professor of Microbiology and Immunology at Jefferson Medical College of Thomas Jefferson University, found that it appears to be due to SNARE-like proteins expressed by the pathogen.

SNARE proteins are necessary for eukaryotic cells to fuse to their intracellular compartments. These proteins, which are present on the surface of almost all intracellular compartments, interact to form a stable complex, triggering fusion of the membranes. Intracellular pathogens, like Chlamydia and Legionella, must contend with vesicular trafficking and membrane fusion in the . But they manage to bypass the lysosome, where other pathogens would normally be destroyed.

The researchers tested the hypothesis that SNARE-like proteins expressed by the themselves were capable to interact with the eukaryotic SNAREs and alter membrane fusion to their advantage. The Chlamydia bacteria expressed a SNARE-like protein called IncA and the Legionella expressed a SNARE-like protein called IcmG/DotF, both of which inhibit SNARE-protein-mediated fusion.

"Based on our results, it seems that intracellular bacteria are able to express 'inhibitory SNAREs' to block fusion between the lysosome and the compartment containing the bacteria," Dr. Paumet said. "The SNARE proteins function like a zipper, and without each half, they can't fuse."

SNARE-like bacterial proteins would appear to be a viable therapeutic target, since disruption of their protective function should render intracellular bacteria more susceptible to clearance from the phagosome.

"Thorough understanding of the bacterial SNARE-like protein system will give us the necessary tools to design such therapeutics," Dr. Paumet said.

Source: Thomas Jefferson University (news : web)

Explore further: Compound from soil microbe inhibits biofilm formation

Related Stories

Biologists search for 'half-fusion'

May 16, 2005

Every living cell is surrounded by a membrane, a thin barrier that separates the genetic machinery of life from the non-living world outside. Though barriers, membranes are not impervious. Cells use a complex hierarchy of ...

Together, biological membranes prevail

Jan 26, 2007

Researchers at the University of Illinois at Urbana-Champaign have developed a novel method to visualize the fusion of biological membranes at the single-event resolution. Observing the individual fusion events revealed an ...

Legionnaire's bacterial proteins work together to survive

Oct 23, 2007

Proteins within the bacteria that cause Legionnaire’s disease can kidnap their own molecular “coffin” and carry it to a safe place within the cell, ensuring their survival, Yale School of Medicine researchers report ...

Recommended for you

Compound from soil microbe inhibits biofilm formation

1 hour ago

Researchers have shown that a known antibiotic and antifungal compound produced by a soil microbe can inhibit another species of microbe from forming biofilms—microbial mats that frequently are medically harmful—without ...

Researcher among best in protein modeling contests

4 hours ago

A Purdue University researcher ranks among the best in the world in bioinformatics competitions to predict protein structure, docking and function, making him a triple threat in the world of protein modeling.

Survey of salmonella species in Staten Island Zoo's snakes

5 hours ago

For humans, Salmonella is always bad news. The bacterial pathogen causes paratyphoid fever, gastroenteritis and typhoid. But for snakes, the bacteria aren't always bad news. Certain species of Salmonella are a natural part ...

A long-standing mystery in membrane traffic solved

Mar 27, 2015

In 2013, James E. Rothman, Randy W. Schekman, and Thomas C. Südhof won the Nobel Prize in Physiology or Medicine for their discoveries of molecular machineries for vesicle trafficking, a major transport ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.