The invader surveillance component of the dynamic duo (an RNA with a viral recognition sequence) comes from sites in the genomes of bacteria and archaea, known technically as "clustered regularly interspaced short palindromic repeats" or more familiarly called CRISPRs. (A palindrome is a word or sentence that reads the same forward and backward.) CRISPR RNAs don't work alone in fighting invaders, though.
Their partners in invader defense are Cas proteins that arise from a suite of genes called "CRISPR-associated" or Cas genes. Together, they form the "CRISPR-Cas system," and the new paper describes this dynamic duo and how they protect bacteria from viruses.
"You can look at one as a police dog that tracks down and latches onto an invader, and the other as a police officer that follows along and `silences' the offender," said Rebecca Terns. "It functions like our own immune system, constantly watching for and neutralizing intruders. But the surveillance is done by tiny CRISPR RNAs rather than antibodies."
What the team discovered was that a particular complex of CRISPR RNAs and a subset of the Cas proteins termed the RAMP module recognizes and destroys invader RNAs that it encounters.
"This work has uncovered intriguing parallels between the bacterial CRISPR-Cas system and the human immune system, suggesting a novel way to target disease-causing bacteria," said Laurie Tompkins, Ph.D., who oversees genetic mechanisms grants at the National Institutes of Health's National Institute of General Medical Sciences. "It may be possible to turn CRISPR-Cas into a suicide machine, killing pathogenic bacteria by an attack on their own molecules, similar to the self-destruction seen in human autoimmune diseases."
|Contact: Phil Williams|
University of Georgia