CRISPRCasjärjestelmä

CRISPRCasjärjestelmä, or cluster regularly interspaced short palindromic repeats and associated proteins, is a natural adaptive immune system found in bacteria and archaea. The system protects microbes from invading genetic elements such as bacteriophages and plasmids by capturing short DNA sequences from the foreign genome and storing them as spacers within CRISPR arrays. When the same or a similar invader reappears, the host transcribes the array into a precursor CRISPR RNA (pre-crRNA). This RNA is processed into multiple short guide RNAs, each containing a spacer region that matches the target DNA. The guide RNA then complexes with a CRISPR-associated (Cas) nuclease, most commonly Cas9, Cas12, or Cas13, forming an RNA-guided ribonucleoprotein that scans the cell for complementary sequences. Upon recognition, the Cas enzyme cleaves the invading nucleic acid, destroying the threat. The system can be subdivided into three stages: adaptation, expression, and interference, each mediated by specific Cas proteins such as Cas1, Cas2, and Cas9.

The discovery of CRISPRCasjärjestelmä’s components led to the development of genome‑editing tools that allow precise addition, disruption, or correction of genes in a wide range of organisms, including mammals, plants, and microorganisms. The most widely used adaptation is a single‑guide RNA that directs Cas9 to a target site adjacent to a protospacer adjacent motif (PAM). This technology has been employed in functional genomics, disease modeling, gene therapy, and agricultural biotechnology.

In addition to targeted editing, CRISPR systems have been retooled for transcriptional regulation, epigenetic modification, and diagnostics. CRISPR‑based diagnostics, such as SHERLOCK and DETECTR, harness collateral cleavage activity of Cas13 and Cas12 to provide highly sensitive detection of nucleic acids. The versatility of the CRISPRCasjärjestelmä framework has positioned it as a cornerstone of modern molecular biology, offering scalable, programmable manipulation of genetic material while raising important ethical and safety considerations that necessitate careful regulation and oversight.