Scientists uncover unique data about 2012 E. coli outbreak strain
The outbreak was responsible for at least 50 deaths and caused kidney failure in almost 1,000 individuals who had developed hemolytic-uremic syndrome, according to HealthCanal.com.
Researchers from Brigham and Women's Hospital, Mount Sinai School of Medicine and Harvard Medical School published their findings about the bacteria in the online version of the journal Nature Biotechnology.
Experts hope the findings will allow scientists to use new approaches in characterizing pathogens, which could subsequently lead to new treatments. The study specifically provides insights into the role of the epigenetic DNA base modifications that drove the molecular processes of the E. coli strain.
During the outbreak, Dr. Eric Schadt, the director of Mount Sinai's Institute for Genomics and Multiscale Biology, worked with colleagues to determine the DNA sequence of the outbreak strain, as well as 11 additional strains. They used the information to help understand the bacteria's evolutionary origins. They did not at that time, however, find the cause for the bacteria's unusually high virulence.
"The information content of the genetic code is not limited to the primary nucleotide sequence of A's, G's, C's and T's," Schadt said, HealthCanal.com reports. "Individual DNA bases can be chemically modified, changing how proteins interact with that particular sequence and as a result having significant functional consequences. Without genome-wide DNA base modification information, you simply don't have a complete picture of all the variation and the phenotypic variability that we see."
The team then used a Pacific Biosciences produced system to determine the type of base modifications that the bacteria underwent. They found that the E. coli outbreak strain had nearly 50,000 methyladenine modified bases. They also discovered a number of enzymes that appeared to target specific DNA sequences.
"We found a whole array of methylase enzymes that were making modifications by targeting different sequence motifs," Schadt, according to HealthCanal.com. "It almost appears like another language. The DNA bases targeted for modification are highly non-random, and the targeting had a broad effect on the transcription of genes."
The team was able to identify structural changes in the genome of the E. coli strain that appear to signify a role in affecting the process that result in high degrees of pathogenicity and virulence.