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KINWALKER(1)			    kinwalker			    KINWALKER(1)

NAME
     kinwalker - predicts RNA folding trajectories

SYNOPSIS
     kinwalker	  [--help]  [--verbose]  [--test]  [--interrupt]  [--printfront]
     [--barrier_heuristic=CHAR]  [--dangle=INT]  [--grouping=STRING]   [--looka-
     head=INT]	[--maxkeep=INT]  [--nolonely=INT]  [--transcribed=INT]	[--tran-
     scription_rate=INT] [--windowsize=INT]

DESCRIPTION
     The Kinwalker algorithm predicts RNA folding trajectories and first passage
     times by connecting the denatured state with the predicted native structure
     through a series of intermediate states.

     Kinwalker splits the folding process into a series  of  events  where  each
     event  can  either  be  a	folding event or a transcription event.  In each
     transcription event one base from the RNA sequence is appended to	the  al-
     ready  transcribed  and  (partially) folded subsequence. Kinwalker executes
     transcription events at regular time intervals. In  each  folding	event  a
     subsequence  of  the already transcribed RNA sequence is selected and a new
     structure is formed by combining base pairs from the current structure with
     base pairs from the mfE structure of that subsequence. This is done in such
     a way that the new structure includes base pairs from both structures in an
     energetically favorable manner.  Kinwalker estimates the waiting times  for
     individual folding events depending on the height of the energy barrier be-
     tween  the  current structure and the new structure into which the molecule
     is folded. Folding events between structures can only occur, if the  energy
     barrier  between  them  is less than the maximum allowed energy barrier. As
     folding paths can only  be  calculated  exhaustively  for	short  sequences
     (n>100),  heuristic  approaches  have  to be employed which explicitly con-
     struct a (re)folding path between the two structures. The saddle height  is
     then  estimated  as  the highest point along the path. The best known algo-
     rithm for approximating saddle heights between  RNA  conformations  is  the
     Morgan-Higgs  heuristic,  which tries to find a folding path from an origin
     secondary structure to a  target  secondary  structure  where  the  maximum
     height along the path is minimal. The heuristic models state transitions at
     base pair resolution.

     Uses  the	ViennaRNA  package  (currently	available at http://www.tbi.uni-
     vie.ac.at/~ivo/RNA/) for free energy calculations and determination of  lo-
     cally optimal substructures.

     Kinwalker	reads  the  RNA sequence from stdin and returns the intermediate
     states of the predicted folding trajectories along with first passage times
     and energy barriers.   Kinwalker  terminates  when  the  mfE  structure  is
     reached.

OPTIONS
     Usage: ./kinwalker [OPTIONS] < SeqFile  > Outfile

	    Options without argument:

     -h,--help
	    Print usage information for ./kinwalker.

     --init_structure
	    Start with a structure other than the open chain.

     --interrupt
	    Allow interrupted folding trajectories when the barrier is exceeded.

     --printfront
	    Creates PS plots of front progression with index i, named front_tra-
	    jectory($i).ps.

     -t,--test
	    Use test sequence.

     -v,--verbose
	    Verbose mode. Print debugging messages about program progress.

	    Options with argument:

     --barrier_heuristic=CHAR
	    'M'  Morgan-Higgs,'S' limits small stacks,'B' Barriers,'A' all, then
	    take minimum. Default: >M<

     --dangle=INT
	    Dangle value of 0,1,2 as in the ViennaRNA package. Default: >0<

     --grouping=STRING
	    How barrier_heuristic 'M' treats conflict groups("standard" or  "re-
	    group"). Default: >standard<

     --lookahead=INT
	    #BP that MorganHiggs forms its subpaths from. Default: >1<

     --maxkeep=INT
	    Breadth  of  breadth first search in barrier_heuristic='B'. Default:
	    >1<

     --nolonely=INT
	    Value of noLonelyPairs as in ViennaRNA. Default: >2<

     --transcribed=INT
	    #bases initially transcribed, <0 means all is transcribed.	Default:
	    >1<)

     --transcription_rate=FLOAT
	    #bases transcribed per second. Default: >200<)

     --windowsize=INT
	    Max size of substructures considered for folding events during tran-
	    scription, 0= all are considered. Default: >0<)

EXAMPLE
     ./kinwalker  --transcribed=50 --transcription_rate=80 --barrier_heuristic=S
     --interrupt --window_size=100 < hok.seq > hok.out

     Computes the folding trajectory of the sequence in hok.seq and writes it to
     hok.out. Folding starts with 50 nucleotide transcribed at	a  transcription
     rate  of  80  nc/sec. Interrupted trajectories are allowed, the 'S' barrier
     heuristic is used and only substructures of length up to 100 nc are consid-
     ered during transcription (windows_size).

     ./kinwalker  --printfront	< hok.seq > hok.out

     Folds the hok.seq sequence with standard parameters, printing  intermediate
     states  of  the  folding trajectory to successive files named front_trajec-
     tory1.ps, front_trajectory2.ps, etc.

FILES
     none

DEPENDENCIES
     ViennaRNA package (http://www.tbi.univie.ac.at/~ivo/RNA/)

AUTHOR
     Michael Geis <michael at bioinf dot uni-leipzig dot de>, Christoph Flamm

REFERENCES
     S. R. Morgan and P. G. Higgs. Barrier heights between ground  states  in  a
     model  of	RNA  secondary	structure,  J.	Phys.  A.: Math. Gen., 31, 1998,
     3153-3170.

     Christoph Flamm and Ivo L. Hofacker and Sebastian Maurer-Stroh and Peter F.
     Stadler and Martin Zehl. Design of Multi-Stable RNA Molecules, RNA, 2000,7,
     254-265.

Michael Geis			       0.1			    KINWALKER(1)

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