title: Partition function and base pairing probabilities of RNA heterodimers.
abstract: BACKGROUND
  RNA has been recognized as a key player in cellular regulation in recent years. In many cases, non-coding RNAs exert their function by binding to other nucleic acids, as in the case of microRNAs and snoRNAs. The specificity of these interactions derives from the stability of inter-molecular base pairing. The accurate computational treatment of RNA-RNA binding therefore lies at the heart of target prediction algorithms.
  
  
  METHODS
  The standard dynamic programming algorithms for computing secondary structures of linear single-stranded RNA molecules are extended to the co-folding of two interacting RNAs.
  
  
  RESULTS
  We present a program, RNAcofold, that computes the hybridization energy and base pairing pattern of a pair of interacting RNA molecules. In contrast to earlier approaches, complex internal structures in both RNAs are fully taken into account. RNAcofold supports the calculation of the minimum energy structure and of a complete set of suboptimal structures in an energy band above the ground state. Furthermore, it provides an extension of McCaskill's partition function algorithm to compute base pairing probabilities, realistic interaction energies, and equilibrium concentrations of duplex structures.
authors.affiliation: Theoretical Biochemistry Group, Institute for Theoretical Chemistry, University of Vienna, Währingerstrasse 17, Vienna, Austria. berni@tbi.univie.ac.at
authors.forename: Stephan H
authors.initials: SH
authors.lastname: Bernhart
authors.forename: Hakim
authors.initials: H
authors.lastname: Tafer
authors.forename: Ulrike
authors.initials: U
authors.lastname: Mückstein
authors.forename: Christoph
authors.initials: C
authors.lastname: Flamm
authors.forename: Peter F
authors.initials: PF
authors.lastname: Stadler
authors.forename: Ivo L
authors.initials: IL
authors.lastname: Hofacker