A critical component of human telomerase, and the first major piece for which a three-dimensional structure is known. Telomerase is an enzyme that maintains the ends of chromosomes. Unlike many other enzymes, which are made of only proteins, it also contains RNA, a single-stranded first cousin to the famous double-helix molecule, DNA. The section of the RNA shown here is essential for the enzyme to function; as biochemist Juli Feigon and her colleagues at UCLA have now shown, it folds up to form a structure that resembles a tightly coiled knot. Another portion of the RNA serves as a kind of template - a scaffolding that guides the new stretch of DNA being constructed on the chromosome's tip.
Credit: Dr. Juli Feigon, UCLA Chemistry and Biochemistry/Molecular Cell