The enzyme had already been shown in previous studies to significantly decrease soft rot in potato plants. The Brandeis and University of Texas team purified the enzyme and identified its structure using X-ray crystallography, an essential step toward developing drugs that may reduce the pathogenicity of bacteria involved in biowarfare threats such as glanders and diseases such as cystic fibrosis.
"This study represents a significant advance in understanding how this enzyme can prevent certain bacteria from becoming virulent," explained Dagmar Ringe of the Rosenstiel Basic Medical Sciences Research Center at Brandeis University. "One of the promising aspects of potential therapies based on this enzyme is that it targets a different pathway than current antibiotics."
The enzyme works by disrupting the ability of certain bacteria to sense their own population growth the key to triggering genes that can increase virulence. In order to sense the size of their own populations, certain bacteria produce small molecules called N-acyl homoserine lactones. The concentrations of these lactones increase along with the growth of the bacterial population. After reaching a threshold concentration, the lactones can "turn on" a variety of genes, often increasing the virulence of the accumulating bacteria.
This population-sensing results in a type of bacterial "group think" because certain genes are not turned on until a minimum number of bacteria are present. Hence, this phenomenon is called quorum-sensing.