Mitochondria are organelles within our cells that generate the majority of chemical energy required to sustain life. They contain a dedicated genome with a special set of genes that need to be expressed to fulfill their function. An important step in mitochondrial gene expression is RNA processing, during which the premature RNA is cut into functional entities by specialized RNA-cutting enzymes. Defects in this process lead to severe human diseases, but the underlying molecular mechanisms are not well understood.
Scientists at the Max Planck Institute (MPI) for Biophysical Chemistry and the University Medical Center Göttingen (UMG) have now determined the molecular mechanism of the first step of RNA processing in human mitochondria. This step is carried out by an enzyme complex called mitochondrial ribonuclease P (mtRNase P). The scientists visualized the structure of this molecular RNA cutting machine using cryo-electron microscopy (cryo-EM).