Jekyll to Hyde key in bacteria: Scientists find gene switch in microbes that may lead to better antibiotics

Vibrio fischeri


Euprymna scolopes

Scientists reported that they had found a key gene in a bacterium which lives in a tiny glowing squid that opens up an intriguing conceptual path in the quest for next-generation antibiotics.
The switch reveals a bacterial pressure point that can be attacked in germs that make us sick, they hope.
The researchers focused on a bacterium called Vibrio fischeri that lives peacefully in a diminutive Pacific creature, the bobtail squid (Euprymna scolopes).
The squid feeds at night near the ocean surface and uses a strain of V.fischeri in its light organ in order to mimic moonlight. The gentle glow acts as a cloaking device to protect the squid from predators.
The investigators pored over the genome of the squid's variant of V.fischeri and compared it with a V.fischeri which lives in a very different host.



This is a pinecone fish, a small reef fish that uses the germ in a light organ in its jaw. Like a flashlight, the glow enables the fish to forage for food at night.
What the team was looking for was the tiny but essential difference between strains that had enabled the bacterium to hole up happily in two very different animal species.
Most of the bacterium's genome was amazingly conserved, pointing to an organism that had been an evolutionary success for millions of years.
The distinction, though, was that the squid's version of V.fischeri had a "regulatory" gene that was not present in the fish's.
The gene acted like a switch.
It turned on other genes that than lay down a biofilm enabling the microbe to colonise the squid's light organ.
The finding is important because human beings, like all forms of life, live in co-existence with bacteria.
Some strains of these bacteria are nasty - or can become that way. Such as the Escherichia coli.
The E.coli can go from a benign or beneficial microorganism in a human to picking up genes that will enable it to become a pathogen.
Therefore, through pinpointing the regulatory gene that prompts a germ to change from the nice "Dr. Jekyll" to the evil "Mr. Hyde" could help the search for treatments that flick the bacterial off-switch, which is useful in curing diseases.




Adapted from "The Star" (2 February 2009)

cool, gene switch~ new stuff~~