CyloFold: secondary structure prediction including pseudoknots

Nucleic Acids Res. 2010 Jul;38(Web Server issue):W368-72. doi: 10.1093/nar/gkq432. Epub 2010 May 25.


Computational RNA secondary structure prediction approaches differ by the way RNA pseudoknot interactions are handled. For reasons of computational efficiency, most approaches only allow a limited class of pseudoknot interactions or are not considering them at all. Here we present a computational method for RNA secondary structure prediction that is not restricted in terms of pseudoknot complexity. The approach is based on simulating a folding process in a coarse-grained manner by choosing helices based on established energy rules. The steric feasibility of the chosen set of helices is checked during the folding process using a highly coarse-grained 3D model of the RNA structures. Using two data sets of 26 and 241 RNA sequences we find that this approach is competitive compared to the existing RNA secondary structure prediction programs pknotsRG, HotKnots and UnaFold. The key advantages of the new method are that there is no algorithmic restriction in terms of pseudoknot complexity and a test is made for steric feasibility.

Availability: The program is available as web server at the site:

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Algorithms
  • Internet
  • Nucleic Acid Conformation
  • RNA / chemistry*
  • Sequence Analysis, RNA
  • Software*


  • RNA