Untying a Knotted SPOUT RNA Methyltransferase by Circular Permutation Results in a Domain-Swapped Dimer (Structure)

An unknotted circular permutant of YbeA was generated to understand how the conserved knotted topology emerged from evolution. Induction of a circular permutation at the knotting loop relieved the mechanical strain essential for maintaining the cofactor in a high-energy configuration, and resulted in a domain-swapped dimer.