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: Study finds cells that become sperm or eggs in humans are vulnerable during pregnancy

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

Bacteria cooperate to repair damaged siblings

17 hours ago

A University of Wyoming faculty member led a research team that discovered a certain type of soil bacteria can use their social behavior of outer membrane exchange (OME) to repair damaged cells and improve ...

New antibody insecticide targets malaria mosquito

May 20, 2015

Malaria is a cruel and disabling disease that targets victims of all ages. Even now, it is estimated to kill one child every minute. Recent progress in halting the spread of the disease has hinged on the ...

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.