1157-60-4Relevant articles and documents
Pseudouridine monophosphate glycosidase: A new glycosidase mechanism
Huang, Siyu,Mahanta, Nilkamal,Begley, Tadhg P.,Ealick, Steven E.
, p. 9245 - 9255 (2012)
Pseudouridine (ψ), the most abundant modification in RNA, is synthesized in situ using ψ synthase. Recently, a pathway for the degradation of ψ was described [Preumont, A., Snoussi, K., Stroobant, V., Collet, J. F., and Van Schaftingen, E. (2008) J. Biol. Chem. 283, 25238-25246]. In this pathway, ψ is first converted to ψ 5′-monophosphate (ψMP) by ψ kinase and then ψMP is degraded by ψMP glycosidase to uracil and ribose 5-phosphate. ψMP glycosidase is the first example of a mechanistically characterized enzyme that cleaves a C-C glycosidic bond. Here we report X-ray crystal structures of Escherichia coli ψMP glycosidase and a complex of the K166A mutant with ψMP. We also report the structures of a ring-opened ribose 5-phosphate adduct and a ring-opened ribose ψMP adduct. These structures provide four snapshots along the reaction coordinate. The structural studies suggested that the reaction utilizes a Lys166 adduct during catalysis. Biochemical and mass spectrometry data further confirmed the existence of a lysine adduct. We used site-directed mutagenesis combined with kinetic analysis to identify roles for specific active site residues. Together, these data suggest that ψMP glycosidase catalyzes the cleavage of the C-C glycosidic bond through a novel ribose ring-opening mechanism.
