ANN ARBOR, Mich. -- Protected by a tough outer coat that is impervious to cold, heat, drought and harsh chemicals, anthrax spores can remain dormant in the soil for decades. Once inside a living host, however, they can germinate and begin infecting cells in as little as ten minutes.
Scientists know very little about what triggers an anthrax spore to break dormancy. Identifying the biochemical signals that start the process is an important first step to preventing anthrax infection.
A new study by University of Michigan scientists John A.W. Ireland, Ph.D., and Philip C. Hanna, Ph.D., shows that germination requires the coordinated activity of several genes, receptor proteins and amino acids in at least two simultaneous signaling pathways. The U-M study, published in the March 2002 issue of the Journal of Bacteriology, is the first to match anthrax genes with specific amino acids and signaling pathways that trigger germination.
"Anthrax doesn't rely on a single signal," says Hanna, an assistant professor of microbiology and immunology in the U-M Medical School. "Endospores have a redundant germination mechanism. It's the bug's way of ensuring that it won't lose its protective armor until conditions are right for germination."
Hanna and Ireland discovered that amino acids, the fundamental building blocks of all proteins in the body, in combination with purine ribonucleosides, the building blocks of DNA and RNA, are triggers for anthrax spore germination. The process appears to begin when receptor proteins on the spore's membrane bind to ring-shaped or aromatic structures on certain amino acids and ribonucleosides.
"The receptor protein is the lock and ring structures are the keys," says Ireland.
"The only place we know where all the required elements for germination are present is inside our cells, especially our phagocy
'"/>
Contact: Sally Pobojewski
pobo@umich.edu
734-615-6912
University of Michigan Health System
27-Feb-2002