The genomes of the two B strains were sequenced at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and at Genoscope, the French center for genome sequencing. Like K-12, the two B genomes each contain about 4.6 million nucleotide base pairs (Ts linked with As or Gs linked with Cs).
"One of the most striking observations in comparing the B and K-12 genomes is the seemingly non-random distribution of single base-pair differences between them," said Maslov, a physicist who studies computationally intensive biological problems. "We are pursuing further analysis to try to understand the evolutionary mechanisms that produced this distribution."
The genome comparisons also turned up some interesting differences between the two B strains. Like identical twins separated at birth, the two B strains have had separate laboratory histories since 1959. One became REL606, a strain used by Richard Lenski at Michigan State University and his collaborators to study long-term evolution in the laboratory. The other became BL21(DE3), a strain developed by Studier and colleagues at Brookhaven Lab to be used as a "factory" for producing proteins for basic research and for medical and industrial use.
"Detailed information about these two strains is useful for future laboratory studies but is also important for companies who are using proteins made from E. coli B strains for medical purposes," Studier said. "They want to know as much as possible about the bacterial strain, including where it came from."
Some detective work was required before the differences between the two B genomes could be understood. Although scientific papers told one story, information in the genome sequences told another, Studier said. The researchers pinpointed the discrepancy to a period in the 1960s, as scientists at different labs shared strains for their research. Apparently, one sample was mislabeled in one of these exchanges. The current de
|Contact: Kendra Snyder|
DOE/Brookhaven National Laboratory