Revisiting GNRA and UNCG folds: U-turns versus Z-turns in RNA hairpin loops.

ABSTRACT: When thinking about RNA three-dimensional structures, coming across GNRA and UNCG tetraloops is perceived as a boon since their folds have been extensively described. Nevertheless, analyzing loop conformations within RNA and RNP structures led us to uncover several instances of GNRA and UNCG loops that do not fold as expected. We noticed that when a GNRA does not assume its "natural" fold, it adopts the one we typically associate with a UNCG sequence. The same folding interconversion may occur for loops with UNCG sequences, for instance within tRNA anticodon loops. Hence, we show that some structured tetranucleotide sequences starting with G or U can adopt either of these folds. The underlying structural basis that defines these two fold types is the mutually exclusive stacking of a backbo

SUBMITTER: D'Ascenzo L 

PROVIDER: S-EPMC5311481 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature