New and Notable Symposium Talk on RNA-Guided Detection and Degradation of Viruses in Bacteria
They say the difference between good actors and great actors is that while a good actor can make an unlikeable character believable, a great actor can make an unlikeable character sympathetic — even a deeply flawed character like the boozing homophobic cowboy Matthew McConaghey portrayed in his Oscar-nominated performance in The Dallas Buyer’s Club. I was thinking of that compelling performance yesterday as I was listening to Blake Wiedenhef of Montana State University leading off the talks in the New and Notable Symposium.
Somehow Wiedenhef had me feeling sympathy for bacteria — those nasty antagonists behind countless plagues since the dawn or time. But bacteria have their own problems. We have known for a long time that they are themselves plagued by infections by bacteriophage viruses. I had no idea just how plagued — Wiedenhef gave an estimate that worldwide, bacteria sustain some 10^24 infections per second.
Fortunately for them, bacteria have evolved various mechanisms to defend themselves against the viral onslaught, and exploring one of these mechanisms was the point of Wiedenhef’s talk. It involves a family of DNA repeats called CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats), which he referred to as “molecular vaccination cards.” Bacteria use them to maintain a genetic record of the viruses they encounter and, with the help of a protein complex, mediate their clearance.
In his talk, Wiedenhef described the first X-ray structure of a CRISPR surveillance system in E.coli: a massive 405 kD assembly of 11 proteins and 1 RNA that forms a complex and allows bacteria defeat viral infections. This impressive structure was illuminated by a nice video his postdoc Ryan Jackson made.
That video won’t help CRISPR win an Oscar next month, but perhaps the insight into the molecular machinery of bacterial adaptive immunity and knowledge of how they defend themselves against the constant viral onslaught may help improve our own odds against some of the viruses and bacteria that plague humankind.