Special Seminar with Prof. Dr Eric Westhof, University of Strasbourg, FR
Mittwoch, 27. September 2017, 17:00 Uhr
Lecture Title: RNA Architecture: Non-Watson-Crick base pairs, RNA Modules, and RNA Puzzles
Abstract: The natural four bases of nucleic acids form a great variety of base pairs with at least two hydrogen bonds between them. They are classified in twelve main families, with the Watson-Crick family being one of them. In a given family, some of the base pairs are isosteric between them, meaning that the positions and the distances between the C1Â’ carbon atoms are very similar. The isostericity of Watson-Crick pairs between the complementary bases forms the basis of RNA helices and of the resulting RNA secondary structure. Several defined suites of non-Watson-Crick base pairs assemble into RNA modules that form recurrent, rather regular, building blocks of the tertiary architecture of folded RNAs. RNA modules are intrinsic to RNA architecture are therefore disconnected from a biological function specifically attached to a RNA sequence. RNA modules occur in all kingdoms of life and in structured RNAs with diverse functions. Because of chemical and geometrical constraints, isostericity between non-Watson-Crick pairs is restricted and this leads to higher sequence conservation in RNA modules with, consequently, greater difficulties in extracting 3D information from sequence analysis. Examples from the group II introns will be emphasized.
RNA-Puzzles is a CASP-like collective blind experiment for the evaluation of RNA three-dimensional structure prediction. The primary aims of RNA-Puzzles are to determine the capabilities and limitations of current methods of 3D RNA structure prediction based on sequence, to find whether and how progress has been made, and to illustrate whether there are specific bottlenecks that hold back the field. Dozens of puzzles have been set up with automatic assessments of the agreements with X-ray structures. Nine groups of modelers around the world participate in this collective effort. Difficulties and progress in RNA structure prediction will be reported.
Raum: Lecture Hall, Y03 G 95