Researchers Uncover New Evidence for Origin of RNA Splicing Within Human Genes; Strongest Evidence to Date That the Spliceosome Evolved from a Bacterial Group II Intron

Old-school Hollywood editors cut unwanted frames of film and patched in desired frames to make a movie. The human body does something similar--trillions of times per second--through a biochemical editing process called RNA splicing. Rather than cutting film, it edits the messenger RNA that is the blueprint for producing the many proteins found in cells. In their exploration of the evolutionary origins and history of RNA splicing and the human genome, UC San Diego biochemists Navtej Toor, PhD, and Daniel Haack, PhD, combined two-dimensional (2D) images of individual molecules to reconstruct a three-dimensional (3D) picture of a portion of RNA--what the scientists call group II introns. In so doing, they discovered a large-scale molecular movement associated with RNA catalysis that provides evidence for the origin of RNA splicing and its role in the diversity of life on Earth. Their breakthrough research is outlined in the July 25, 2019 issue of Cell. The article is titled “Cryo-EM Structures of a Group II Intron Reverse Splicing into DNA.” "We are trying to understand how the human genome has evolved starting from primitive ancestors. Every human gene has unwanted frames that are non-coding and must be removed before gene expression. This is the process of RNA splicing," stated Dr. Toor, an Associate Professor in the Department of Chemistry and Biochemistry, adding that 15 percent of human diseases are the result of defects in this process.
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