evades body's defenses
Yale scientist Jorge Galan and his colleagues in the Section of Microbial Pathogenesis at the School of Medicine report a new and fundamental mechanism that Salmonella bacteria use to replicate within a body's cells and cause disease without being endangered by the body's defense mechanisms.
The work appeared in the June 18 issue of Science.
Most dangerous bacteria that enter the body are engulfed and digested by cells called macrophages. Once inside a macrophage, the bacteria are targeted for death by a mechanism that transports them within a vesicle to a specialized compartment, the lysozome, designed to degrade foreign or unwanted materials.
Once the bacterium is engulfed, it takes only about 30 minutes to reach a lysozome. Therefore, to survive and replicate, bacteria must act rapidly to avoid this pathway to degradation. Salmonella, the bacterium that causes food poisoning and typhoid fever, is able to do just that.
"Salmonella have an elegant strategy for surviving and replicating and avoiding this cellular disposal system," explains Galan, the Lucille P. Markey Professor of Microbiology and chair of the Section of Microbial Pathogenesis. "We found that these bacteria alter the lipid composition of the vacuole, or compartment, they are in so that it cannot progress down the standard path to the lysozome and destruction."
To accomplish this, the Salmonella bacteria use a "syringe-like" device called the type III secretion system to deliver a protein, SopB, which has phosphoinositide phosphatase activity and modifies the composition of the vacuole that encloses them.
"While this research is not a cure for food poisoning or typhoid fever, our work is revealing a fundamental mechanism by which these bacteria cause disease -- and may provide or lead to new targets for the development of novel therapeutic strategies for controlling them," says Galan.
Other investigators involved in the study were Lorraine Hernandez and Karsten Hueffer from the Section of Microbial Pathogenesis, and Markus Wenk, currently at Merck Research Laboratories and formerly from the Department of Cell Biology at Yale. The work was funded by a fellowship from the Damon Runyon-Walter Winchell Foundation and by a Public Health Service Grant from the National Institutes of Health.
-- By Janet Rettig Emanuel
T H I S
W E E K ' SS T O R I E S
Gift from alumnus helps fund new home for F&ES
Team learns how bacteria evades body's defenses
Grants will advance research on important health issuesPreventing HIV infection in India's at-risk populations
Understanding the causes of autism in infants
Treating patients with MS and spinal cord injuries
Brain power
ENDOWED PROFESSORSHIPSJohn Hartwig is Irénée duPont Professor of Chemistry
Shelly Kagan named Clark Professor of Philosophy
Jay Winter designated as the Stille Professor of History
Keith Wrightson is the Townsend Jr. Professor of History
Wimbledon winner, future Olympians to compete in Pilot Pen tournament
IN FOCUS: Yale Health Plan
Works by Cuban artists on view in 'Intersections/Intersecciones' exhibit
Bouchet Award recognizes scientist's effort to promote diversity
F&ES hosts delegation from China
Deserts, rainforests equally productive during drought, says study
EPA certificate of recognition awarded to Yale power plant
IN MEMORIAM: Edmund Slocum Crelin Jr.: newborn anatomy expert
CANCER CENTER APPOINTMENTSDr. Ira Mellman, new scientific director, will enhance partnership
Dr. Edward Chu will oversee the medical oncology section
Researchers receive grants for studies on women's health issues
New 'advocates' for theater are named to council
Genetics professor wins award to study prostate cancer . . .
Nursing professor Kathleen Knafl to chair group . . .
Art Gallery's new development director to head . . .
Yale Books in Brief
Campus Notes
Bulletin Home|Visiting on Campus|Calendar of Events|In the News
Bulletin Board|Classified Ads|Search Archives|Deadlines
Bulletin Staff|Public Affairs|News Releases|
E-Mail Us|Yale Home