CHAMPAIGN, Ill. — While working out the structure of a cell-
killing protein produced by some strains of the bacterium
Enterococcus faecalis, researchers stumbled on a bit of unusual
biochemistry. They found that a single enzyme helps form
distinctly different, three-dimensional ring structures in the
protein, one of which had never been observed before. The new
findings, reported in Nature Chemical Biology, should help
scientists find new ways to target the enterococcal cytolysin
protein, a "virulence factor that is associated with acute
infection in humans," said University of Illinois chemistry and
Institute for Genomic Biology professor Wilfred van der Donk,
who conducted the study with graduate student Weixin Tang.
Enterococcus faecalis (EN-ter-oh-cock-us faye-KAY-liss) is a
normal microbial inhabitant of the gastrointestinal tracts of
humans and other mammals and generally does not harm its host.
Some virulent strains, however, produce cytolysin (sigh-toe-LIE-
sin), a protein that, once assembled, attacks