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
Grant to aid development of gene therapy for Parkinson's
Alumni elect new trustee
Historian Blight to direct Gilder-Lehrman Center
Student's 'Ride to Endure' will raise funds for cancer group
ENDOWED PROFESSORSHIPSAnne Alstott is designated the Bierman Professor
Jon Butler appointed the Howard R. Lamar Professor
Andrew Hamilton named the Silliman Professor
Library acquires papers of famed poet Joseph Brodsky
IN FOCUS: F&ES-Anthropology Combined Degree
Troup students creating own plays in Drama School program
SCIENCE & MEDICAL NEWSScientist wins grant for largest-ever field study on Lyme disease
Astronomers gather to share research about the sun
Grant to support Nobel laureate's RNA studies
Team captures image of RNA splicing complex
Report shows rising risk of metabolic syndrome . . .
Research shows ability to identify suspects is poor . . .
Study: Unusual protein may play role in asthma
Psychologists say attitudes are only as strong as you say they are
Researcher examining gap between low rate of breast cancer . . .
Marijuana ingredient linked to schizophrenia-like symptoms
Scientists use altered virus to 'light up' MCH neurons
Mathematician elected to oldest learned society in U.S.
Study: Mammals' olfactory system matures in different stages
Presentations from rice symposium now online
Committee reviewing employee health benefits . . .
Orchestral movement: Shinik Hahm leaving post . . .
Ranis and Hathaway to research international topics as Carnegie Scholars
I. Richard Savage dies; noted for applying statistics to public policys
Sundance Lab director named interim head of playwriting department
Campus Notes
ONLY ON THE WEB
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