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Protonation‐Dependent Base Flipping at Neutral pH in the Catalytic Triad of a Self‐Splicing Bacterial Group II Intron
Author(s) -
Pechlaner Maria,
Donghi Daniela,
Zelenay Veronika,
Sigel Roland K. O.
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201504014
Subject(s) - catalytic triad , protonation , triad (sociology) , catalysis , chemistry , linker , rna splicing , group ii intron , stereochemistry , crystallography , intron , stacking , active site , biochemistry , ion , rna , organic chemistry , gene , psychology , computer science , psychoanalysis , operating system
Abstract NMR spectroscopy has revealed pH‐dependent structural changes in the highly conserved catalytic domain 5 of a bacterial group II intron. Two adenines with p K a values close to neutral pH were identified in the catalytic triad and the bulge. Protonation of the adenine opposite to the catalytic triad is stabilized within a G( syn )–AH + ( anti ) base pair. The pH‐dependent anti ‐to‐ syn flipping of this G in the catalytic triad modulates the known interaction with the linker region between domains 2 and 3 (J23) and simultaneously the binding of the catalytic Mg 2+ ion to its backbone. Hence, this here identified shifted p K a value controls the conformational change between the two steps of splicing.