Researchers have gained major insight into how enzymes have the ability to "edit" genes; the findings could lead to breakthroughs in the treatment of genetic diseases.
Scientists observed how a class of enzymes called CRISPR "bind and alter" DNA structures, a University of Bristol news release reported.
These enzymes were first discovered in in bacteria back in the 1980s; it was used as an immune defense against invading viruses.
Recently, scientists have found that a type of CRISPR enzyme, called Cas9, has the ability to "edit" the human genome.
The unique enzyme is specially "tailored" to seek out single letter combinations using three million base pairs of a DNA molecule.
"This is the equivalent of correcting a single misspelt word in a 23-volume [encyclopedia]," the news release reported.
To find this obscure error CRISPR uses an RNA molecule, which is a "nucleic acid similar in structure to DNA," the news release reported.
In order to hit its target CRISPR pulls apart DNA strands and inserts the RNA to form a "sequence-specific structure called an 'R-loop.'"
The team tested their R-loop model using microscopes that use a magnetic field to stretch single DNA molecules. This allowed the team to observe previously unknown steps in the process.
"An important challenge in exploiting these exciting genome editing tools is ensuring that only one specific location in a genome is targeted," Professor Mark Szczelkun, from Bristol University's School of Biochemistry, said in the news release. "Our single molecule assays have led to a greater understanding of the influence of DNA sequence on R-loop formation. In the future this will help in the rational re-engineering of CRISPR enzymes to increase their accuracy and [minimize] off-target effects. This will be vital if we are to ultimately apply these tools to correct genetic diseases in patients. "
