A recent investigative report by Steve Silberman from Wired about the highly resistant Acinetobacter baumannii, encountered by clinicians treating wounded in Iraq, has put the nasty bacterium on the public’s radar screen.
Yale University is reporting on the progress that its scientists were able to make analyzing the bug’s genome:
The DNA sequence analysis of A. baumannii revealed several important features including some that may allow researchers to design better drugs to treat infection. It showed that fully 17% of the DNA that codes for protein in this microorganism is present in “alien islands,” or sequences that originated in other microorganisms.
“It is like an old pair of jeans — no pun intended — which have been patched so many times that the patches represent a significant portion of the structure,” says Snyder. [Michael Snyder is Professor of Molecular, Cellular & Developmental Biology at Yale –ed.] “Although not originally part of the organism, these ‘alien island’ sequences have become integrated into the A. baumannii DNA and now represent a significant portion of that genome.”
Bacteria typically acquire alien DNA from other microorganisms through a process known as “horizontal gene transfer,” and alien DNA is more likely to be retained and passed down to next generations of bacteria when it provides a survival benefit. This study reported that 16 of the presumed 28 alien islands in A. baumannii contain genes implicated in virulence.
Two of the alien islands identified contained genes that did not match known sequences in the databases. The experiments showed that genes in those islands were important for virulence by selectively inactivating them and causing a loss of virulence. The authors suggest that these newly identified virulence genes may be good targets for antimicrobial drug development in addition to providing insight into the way organisms evolve virulence.
The researchers used a combination of cutting-edge technologies, including the high-density DNA pyro-sequencing process developed by 454 Life Sciences and functional screening via transposon mutagenesis. Using this process the genome of a comparable microbe could be sequenced and analyzed completely in only a few weeks, according to Snyder.
The researchers used a combination of cutting-edge technologies, including the high-density DNA pyro-sequencing process developed by 454 Life Sciences and functional screening via transposon mutagenesis. Using this process the genome of a comparable microbe could be sequenced and analyzed completely in only a few weeks, according to Snyder.The best (and the quickest) way to learn more about the amazing 454’s rapid shot-gun sequencing technology is to check out this flash animation. For more, head on to the technology page at 454…
Full report from Yale…
The Genome Sequencer 20™ System product page and flash demo…
Genome sequencing in microfabricated high-density picolitre reactors (.pdf) paper at Nature (doi:10.1038/nature03959)…
Press release from 454 Life Sciences…