The story of when was crispr cas9 discovered begins not with a single experiment, but with the quiet observation of strange, repeating DNA sequences in bacterial genomes during the late 1980s. Researchers sequencing the genome of *Escherichia coli* noticed a pattern of short, identical repeats separated by unique spacers, a genetic puzzle that would remain unsolved for more than a decade. This fundamental discovery of the clustered regularly interspaced short palindromic repeats, or CRISPR, system laid the groundwork for a revolution in genetic engineering, though its monumental potential was not yet understood.
The Initial Discovery of the CRISPR Locus
In 1987, Yoshizumi Ishino and his team at Osaka University in Japan published the first description of what would become known as the CRISPR array. While investigating the iap gene, which codes for an alkaline phosphatase isozyme, they inadvertently cloned a long stretch of DNA containing multiple identical repeats. This finding, published in the *Journal of Bacteriology*, represented the initial documentation of the CRISPR phenomenon, but the functional significance of these repeats was entirely speculative at the time. The scientific community lacked the context to appreciate that this was a previously unknown adaptive immune system.
Filling the Genetic Gaps
Following the initial discovery, the focus shifted from observation to classification. During the 1990s, independent research groups began identifying similar repeat-spacer arrays in other bacteria and archaea. A pivotal moment occurred in 1993 when researchers studying the genome of *Mycobacterium tuberculosis* noted these repeat structures and proposed the name "CRISPR" to describe them. This period was crucial for establishing that CRISPR was a widespread genomic feature, not an anomaly confined to a single bacterial species, setting the stage for the next phase of inquiry into its biological purpose.
Deciphering the Immune Function
The critical leap from describing CRISPR to understanding its function came in the early 2000s. Francisco Mojica, working at the University of Alicante in Spain, was instrumental in hypothesizing that CRISPR served as an immune system. He proposed that the spacers—DNA fragments derived from invading viruses—acted as a molecular memory bank. This theory was solidified between 2005 and 2006 when multiple labs, including those led by Philippe Horvath and Alexander Bolotin, demonstrated that CRISPR loci provided resistance to phage infection. The when was crispr cas9 question began to converge on the realization that the system required associated Cas proteins to function.
The Identification of Cas9
The defining component of the system, the Cas9 protein, was characterized in 2012 by Jennifer Doudna and Emmanuelle Charpentier. Their breakthrough work demonstrated that Cas9, guided by a synthetic RNA strand, could be programmed to cut any DNA sequence of choice. This was the pivotal discovery that transformed CRISPR from a bacterial curiosity into a universal gene-editing tool. The publication of this research provided the clear methodology that made precise genome editing accessible to labs worldwide, effectively launching the entire field of biotechnology.
The Modern Era and Patent Landscape
While the foundational work on the CRISPR-Cas9 system was published in 2012 and 2013, the timeline of discovery extends into ongoing legal and scientific discourse. The Feng Zhang group at the Broad Institute filed key patents in 2012 concerning the use of CRISPR-Cas9 in eukaryotic cells, leading to a complex patent dispute with the University of California. This legal battle highlights the race to define intellectual property in what became a trillion-dollar industry. The application of the discovery rapidly outpaced the initial research, moving from bacterial immunity to human therapeutics with astonishing speed.
