Group II B Intron and CPEB3
Ribozymes are catalytically active RNA molecules or RNA–protein complexes, in which solely the RNA provides catalytic activity. The term ribozyme refers to the enzymatic activity and ribonucleic acid nature at the same time. Ribozymes are found in the genomes of species from all kingdoms of life.
One example of a large ribozyme is the group II intron Sc.ai5γ originated from S. cerevisiae. It folds into a defined 3D-structure and simultaneously induces its self-cleavage from the precursor mRNA. We want to understand both mechanisms, the splicing and the folding, exploring them by labelling the RNA fluorescently for e.g. smFRET studies and activity assays. Additionally, we are applying NMR, X-Ray and MD-Simulations to obtain more insights into important structural elements. [1,2]
Another ribozyme of interest in our group is the cytoplasmic polyadenylation element-binding 3 (CPEB3) ribozyme. It is one of the very few small ribozymes identified in mammalian genomes, including also humans. The CPEB3 ribozyme belongs to the hepatitis delta virus (HDV)-like family of ribozymes that fold into an intricate 'nested double pseudoknot' and are capable for self-cleavage through a transesterification reaction. Our goal is to solve the three-dimensional structure of the CPEB3 ribozyme by NMR spectroscopy and X-ray crystallography as well as to understand the role of Mg2+-ions for the folding and cleavage process. 
 Miriam Steiner, Krishanti S. Karunatilaka, Roland K. O. Sigel*, David Rueda*, Proc. Natl. Acad. Sci. USA, 2008, 105, 13853-13858.
 Michèle C. Erat, Roland K. O. Sigel*, J. Biol. Inorg. Chem., 2008, 13, 1025-1036.
 Miriam Steiner, David Rueda*, Roland K. O. Sigel*, Angew. Chem. Int. Ed. Engl., 2009, 48, 13853-13858.
 Miriam Skilandat, Magdalena Rowinska-Zyrek, Roland K. O. Sigel*, RNA, 2016, 22, 750-763.