RNAalifold − manual page for RNAalifold 2.1.5
RNAalifold [options] <file1.aln>
calculate secondary structures for a set of aligned RNAs
RNA sequences from stdin or file.aln and calculate their
minimum free energy (mfe) structure, partition function (pf)
and base pairing probability matrix. Currently, the input
alignment has to be in CLUSTAL format. It returns the mfe
structure in bracket notation, its energy, the free energy
of the thermodynamic ensemble and the frequency of the mfe
structure in the ensemble to stdout. It also produces
Postscript files with plots of the resulting secondary
structure graph ("alirna.ps") and a "dot
plot" of the base pairing matrix
("alidot.ps"). The file "alifold.out"
will contain a list of likely pairs sorted by credibility,
suitable for viewing with "AliDot.pl". Be warned
that output file will overwrite any existing files of the
Print help and exit
Print help, including all details and hidden options, and exit
Print help, including hidden options, and exit
Print version and exit
Below are command line options which alter the general behavior of this program
Calculate structures subject to constraints. The constraining structure will be read from ’stdin’, the alignment has to be given as a file name on the command line.
The program reads first the sequence, then a string containing constraints on the structure encoded with the symbols:
. (no constraint for this base)
| (the corresponding base has to be paired
x (the base is unpaired)
< (base i is paired with a base j>i)
> (base i is paired with a base j<i)
and matching brackets ( ) (base i pairs base j)
With the exception of "|", constraints will disallow all pairs conflicting with the constraint. This is usually sufficient to enforce the constraint, but occasionally a base may stay unpaired in spite of constraints. PF folding ignores constraints of type "|".
Produce a colored version of the consensus strcture plot "alirna.ps" (default b&w only)
Produce a colored and structure annotated alignment in PostScript format in the file "aln.ps" in the current directory.
Do not produce postscript output
Select additional algorithms which should be included in the calculations. The Minimum free energy (MFE) and a structure representative are calculated in any case.
Calculate the partition function and base pairing probability matrix in addition to the mfe structure. Default is calculation of mfe structure only.
In addition to the MFE structure we print a coarse representation of the pair probabilities in form of a pseudo bracket notation, followed by the ensemble free energy, as well as the centroid structure derived from the pair probabilities together with its free energy and distance to the ensemble. Finally it prints the frequency of the mfe structure.
An additionally passed value to this option changes the behavior of partition function calculation: −p0 deactivates the calculation of the pair probabilities, saving about 50% in runtime. This prints the ensemble free energy −kT ln(Z).
Calculate an MEA (maximum expected accuracy) structure.
If gamma is not specified a default of gamma=1 is used. Using −−MEA implies −p See also RNAfold man page for details.
Output "most informative sequence" instead of simple consensus: For each column of the alignment output the set of nucleotides with frequence greater than average in IUPAC notation.
Stochastic backtrack. Compute a certain number of random structures with a probability dependend on the partition function. See −p option in RNAsubopt.
same as "−s" but also print out the energies and probabilities of the backtraced structures.
−S, −−pfScale=scaling factor
In the calculation of the pf use scale*mfe as an estimate for the ensemble free energy (used to avoid overflows).
The default is 1.07, useful values are 1.0 to 1.2. Occasionally needed for long sequences. You can also recompile the program to use double precision (see the README file).
Assume a circular (instead of linear) RNA molecule.
Set the threshold for base pair probabilities included in the postscript output
By setting the threshold the base pair probabilities that are included in the output can be varied. By default only those exceeding 1e−5 in probability will be shown as squares in the dot plot. Changing the threshold to any other value allows for increase or decrease of data.
Incoorporate G−Quadruplex formation into the structure prediction algorithm
Rescale energy parameters to a temperature of temp C. Default is 37C.
Do not include special tabulated stabilizing energies for tri−, tetra− and hexaloop hairpins. Mostly for testing.
How to treat "dangling end" energies for bases adjacent to helices in free ends and multi−loops
With −d2 dangling energies will be added for the bases adjacent to a helix on both sides
in any case.
The option −d0 ignores dangling ends altogether (mostly for debugging).
Produce structures without lonely pairs (helices of length 1).
For partition function folding this only disallows pairs that can only occur isolated. Other pairs may still occasionally occur as helices of length 1.
Do not allow GU pairs
Do not allow GU pairs at the end of helices
Set the weight of the covariance term in the energy function
Set the penalty for non−compatible sequences in the covariance term of the energy function
Score pairs with endgaps same as gap−gap pairs.
use specified Ribosum Matrix instead of normal
energy model. Matrixes to use should be 6x6 matrices, the order of the terms is AU, CG, GC, GU, UA, UG.
use ribosum scoring matrix. The matrix is chosen according to the minimal and maximal pairwise identities of the sequences in the file.
use old energy evaluation, treating gaps as characters.
Read energy parameters from paramfile, instead of using the default parameter set.
A sample parameter file should accompany your distribution. See the RNAlib documentation for details on the file format.
Allow other pairs in addition to the usual AU,GC,and GU pairs.
Its argument is a comma separated list of additionally allowed pairs. If the first character is a "−" then AB will imply that AB and BA are allowed pairs. e.g. RNAfold −nsp −GA will allow GA and AG pairs. Nonstandard pairs are given 0 stacking energy.
Rarely used option to fold sequences from the artificial ABCD... alphabet, where A pairs B, C−D etc. Use the energy parameters for GC (−e 1) or AU (−e 2) pairs.
Set the scaling of the Boltzmann factors (default=‘1.’)
The argument provided with this option enables to scale the thermodynamic temperature used in the Boltzmann factors independently from the temperature used to scale the individual energy contributions of the loop types. The Boltzmann factors then become exp(−dG/(kTn*betaScale)) where k is the Boltzmann constant, dG the free energy contribution of the state, T the absolute temperature and n the number of sequences.
Sequences are not weighted. If possible, do not mix very similar and dissimilar sequences. Duplicate sequences, for example, can distort the prediction.
Ivo L Hofacker, Stephan Bernhart, Ronny Lorenz
If you use this program in your work you might want to cite:
R. Lorenz, S.H. Bernhart, C. Hoener zu Siederdissen, H. Tafer, C. Flamm, P.F. Stadler and I.L. Hofacker (2011), "ViennaRNA Package 2.0", Algorithms for Molecular Biology: 6:26
I.L. Hofacker, W. Fontana, P.F. Stadler, S. Bonhoeffer, M. Tacker, P. Schuster (1994), "Fast Folding and Comparison of RNA Secondary Structures", Monatshefte f. Chemie: 125, pp 167-188
The algorithm is a variant of the dynamic programming algorithms of M. Zuker and P. Stiegler (mfe) and J.S. McCaskill (pf) adapted for sets of aligned sequences with covariance information.
Ivo L. Hofacker, Martin Fekete, and Peter F. Stadler (2002), "Secondary Structure Prediction for Aligned RNA Sequences", J.Mol.Biol.: 319, pp 1059-1066.
Stephan H. Bernhart, Ivo L. Hofacker, Sebastian Will, Andreas R. Gruber, and Peter F. Stadler (2008), "RNAalifold: Improved consensus structure prediction for RNA alignments", BMC Bioinformatics: 9, pp 474
The energy parameters are taken from:
D.H. Mathews, M.D. Disney, D. Matthew, J.L. Childs, S.J. Schroeder, J. Susan, M. Zuker, D.H. Turner (2004), "Incorporating chemical modification constraints into a dynamic programming algorithm for prediction of RNA secondary structure", Proc. Natl. Acad. Sci. USA: 101, pp 7287-7292
D.H Turner, D.H. Mathews (2009), "NNDB: The nearest neighbor parameter database for predicting stability of nucleic acid secondary structure", Nucleic Acids Research: 38, pp 280-282
If in doubt our
program is right, nature is at fault.
Comments should be sent to firstname.lastname@example.org.
The ALIDOT package http://www.tbi.univie.ac.at/RNA/ALIDOT/