Nobel prize worthy new method to edit genetic material of living things

 

"Dr. Charpentier and Dr. Doudna both stumbled across Crispr by accident. Dr. Charpentier, a microbiologist, spent a number of years studying Streptococcus pyogenes, a species of bacteria that causes scarlet fever and other diseases. Inspecting the microbe’s DNA in 2006, she and her colleagues discovered a puzzling series of repeating segments.

A few scientists had studied these segments since the 1980s, but no one was sure of their function. Francisco Mojica, a microbiologist at the University of Alicante in Spain, gave these DNA stretches a name in 2000: clustered regularly interspaced short palindromic repeats, or Crispr for short.

A palindrome is a word, number, phrase, or other sequence of characters which reads the same backward as forward, such as madam, racecar

Dr. Mojica and other researchers spent the 1990s and early 2000s trying to determine why microbes had this mysterious repetitive DNA. It became clear that between these repeats were bits of genetic material derived from viruses that had tried to infect the bacteria. Somehow, the bacteria were grabbing bits of viral genes and storing them away. It was if they were creating an archive of past infections, which they could later use to defend against future attacks.

Dr. Charpentier and her colleagues discovered some of the key steps by which the bacteria used this information to attack viruses. The bacteria made molecules of RNA — ribonucleic acid, a cousin of DNA — that recognized the genes of attacking viruses.

After writing a paper on their discovery in 2011, Dr. Charpentier recognized she needed to collaborate with an expert on RNA molecules to make more progress. That expert was Dr. Doudna.

Dr. Doudna (the first syllable rhymes with loud) had never heard of Crispr until another Berkeley scientist, microbiologist Jill Banfield, brought it to her attention in 2006. Until then, she had studied how bacteria make RNA molecules for other purposes, such as sensing the environment and silencing certain genes.

Dr. Charpentier, 51, and Dr. Doudna, 56, met at a cafe in Puerto Rico in 2011 while attending a scientific conference and immediately started to collaborate on understanding how Crispr worked. Soon, they realized that they might be able to harness the RNA molecules to seek out and alter any piece of DNA.

Bacteria defend themselves by using these molecules to recognize the genes of an attacking virus. The weaponry includes an enzyme called Cas9 that slices the viral genetic material.

Dr. Charpentier and Dr. Doudna realized that they could synthesize a piece of RNA that targeted and chopped up not just a spot on a viral gene — but on any gene. In 2012, the scientists proved this concept could work.

Crispr was not the first tool scientists invented to alter DNA. But previous methods were relatively crude, involving expensive, cumbersome machines and materials. Crispr could become a far more precise genetic surgery.

If researchers used Crispr molecules to make cuts at two neighboring sites on a piece of DNA, for example, the DNA stretch would heal, sewing itself together without the sliced segment. It became possible to insert a new piece of DNA in the place of the removed one. Subsequent research revealed how to use Crispr to alter single genetic letters.

What had begun as an ancient system of antiviral defense quickly became one of the most powerful and precise genome-editing tools available to science. In less than a decade, Crispr has become commonplace in laboratories around the world."

Bacteria create an archive of past infections in the form of this Crispr system. We humans also create an archive of past infections in our bodies, which is the basis of our immunity, disease resistance. Thus, Crispr is a kind of basis for bacterial immunity, resistance to viral infections.