Cortex peptidoglycan lytic activity in germinating Bacillus anthracis spores

Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061

^* To whom correspondence should be addressed. Email: dpopham{at}vt.edu.

	Abstract

Bacterial endospore dormancy and resistance properties depend on the relative dehydration of the spore core, which is maintained by the spore membrane and its surrounding cortex peptidoglycan wall. During spore germination, the cortex peptidoglycan is rapidly hydrolyzed by lytic enzymes packaged into the dormant spore. The peptidoglycan structures in both dormant and germinating Bacillus anthracis Sterne spores were analyzed. B. anthracis dormant spore PG was similar to that found in other species. During germination, B. anthracis released peptidoglycan fragments into the surrounding medium more quickly than some other species. A major lytic enzymatic activity was a glucosaminidase, probably YaaH, that cleaved between N-acetylglucosamine and muramic--lactam. An epimerase activity previously proposed to function on spore peptidoglycan was not detected, and it is newly proposed that glucosaminidase products were previously misidentified as epimerase products. Spore cortex lytic enzymes and their regulators are attractive targets for development of germination inhibitors, to kill spores, and activators, to cause loss of resistance properties, for decontamination of sites of spore release.