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Man Pages


Manual Reference Pages  -  HMMBUILD (1)

NAME

hmmbuild - construct profile HMM(s) from multiple sequence alignment(s)

CONTENTS

Synopsis
Description
Options
Options For Specifying The Alphabet
Options Controlling Profile Construction
Options Controlling Relative Weights
Options Controlling Effective Sequence Number
Options Controlling E-value Calibration
Other Options
See Also
Copyright
Author

SYNOPSIS

hmmbuild [options] hmmfile msafile

DESCRIPTION

Build a profile HMM for each multiple sequence alignment in msafile, and save it to a new file hmmfile.

OPTIONS

-h Help; print a brief reminder of command line usage and all available options.

-n <s>
  Name the new profile <s>. The default is to use the name of the alignment (if one is present in the msafile, or, failing that, the name of the hmmfile. If msafile contains more than one alignment, -n doesn’t work, and every alignment must have a name annotated in the msafile (as in Stockholm #=GF ID annotation).

-o <f>
  Direct the summary output to file <f>, rather than to stdout.

-O <f>
  After each model is constructed, resave annotated, possibly modified source alignments to a file <f> in Stockholm format. The alignments are annotated with a reference annotation line indicating which columns were assigned as consensus, and sequences are annotated with what relative sequence weights were assigned. Some residues of the alignment may have been shifted to accommodate restrictions of the Plan7 profile architecture, which disallows transitions between insert and delete states.

OPTIONS FOR SPECIFYING THE ALPHABET

The alphabet type (amino, DNA, or RNA) is autodetected by default, by looking at the composition of the msafile. Autodetection is normally quite reliable, but occasionally alphabet type may be ambiguous and autodetection can fail (for instance, on tiny toy alignments of just a few residues). To avoid this, or to increase robustness in automated analysis pipelines, you may specify the alphabet type of msafile with these options.

--amino
  Specify that all sequences in msafile are proteins.

--dna Specify that all sequences in msafile are DNAs.

--rna Specify that all sequences in msafile are RNAs.

OPTIONS CONTROLLING PROFILE CONSTRUCTION

These options control how consensus columns are defined in an alignment.

--fast
  Define consensus columns as those that have a fraction >= symfrac of residues as opposed to gaps. (See below for the --symfrac option.) This is the default.

--hand Define consensus columns in next profile using reference annotation to the multiple alignment. This allows you to define any consensus columns you like.

--symfrac <x>
  Define the residue fraction threshold necessary to define a consensus column when using the default --fast construction option. The default for --symfrac is 0.5. The symbol fraction in each column is calculated after taking relative sequence weighting into account, and ignoring gap characters corresponding to ends of sequence fragments (as opposed to internal insertions/deletions). Setting this to 0.0 means that every alignment column will be assigned as consensus, which may be useful in some cases. Setting it to 1.0 means that only columns that have no gap characters at all will be assigned as consensus.

--fragthresh <x>
  We only want to count terminal gaps as deletions if the aligned sequence is known to be full-length, not if it is a fragment (for instance, because only part of it was sequenced). HMMER uses a simple rule to infer fragments: if the sequence length L is less than a fraction <x> times the mean sequence length of all the sequences in the alignment, then the sequence is handled as a fragment. The default is 0.5.

OPTIONS CONTROLLING RELATIVE WEIGHTS

HMMER uses an ad hoc sequence weighting algorithm to downweight closely related sequences and upweight distantly related ones. This has the effect of making models less biased by uneven phylogenetic representation. For example, two identical sequences would typically each receive half the weight that one sequence would. These options control which algorithm gets used.

--wpb Use the Henikoff position-based sequence weighting scheme [Henikoff and Henikoff, J. Mol. Biol. 243:574, 1994]. This is the default.

--wgsc
  Use the Gerstein/Sonnhammer/Chothia weighting algorithm [Gerstein et al, J. Mol. Biol. 235:1067, 1994].

--wblosum
  Use the same clustering scheme that was used to weight data in calculating BLOSUM subsitution matrices [Henikoff and Henikoff, Proc. Natl. Acad. Sci 89:10915, 1992]. Sequences are single-linkage clustered at an identity threshold (default 0.62; see --wid) and within each cluster of c sequences, each sequence gets relative weight 1/c.

--wnone
  No relative weights. All sequences are assigned uniform weight.

--wid <x>
  Sets the identity threshold used by single-linkage clustering when using --wblosum. Invalid with any other weighting scheme. Default is 0.62.

OPTIONS CONTROLLING EFFECTIVE SEQUENCE NUMBER

After relative weights are determined, they are normalized to sum to a total effective sequence number, eff_nseq. This number may be the actual number of sequences in the alignment, but it is almost always smaller than that. The default entropy weighting method (--eent) reduces the effective sequence number to reduce the information content (relative entropy, or average expected score on true homologs) per consensus position. The target relative entropy is controlled by a two-parameter function, where the two parameters are settable with --ere and --esigma.

--eent Adjust effective sequence number to achieve a specific relative entropy per position (see --ere). This is the default.

--eclust
  Set effective sequence number to the number of single-linkage clusters at a specific identity threshold (see --eid). This option is not recommended; it’s for experiments evaluating how much better --eent is.

--enone
  Turn off effective sequence number determination and just use the actual number of sequences. One reason you might want to do this is to try to maximize the relative entropy/position of your model, which may be useful for short models.

--eset <x>
  Explicitly set the effective sequence number for all models to <x>.

--ere <x>
  Set the minimum relative entropy/position target to <x>. Requires --eent. Default depends on the sequence alphabet; for protein sequences, it is 0.59 bits/position.

--esigma <x>
  Sets the minimum relative entropy contributed by an entire model alignment, over its whole length. This has the effect of making short models have higher relative entropy per position than --ere alone would give. The default is 45.0 bits.

--eid <x>
  Sets the fractional pairwise identity cutoff used by single linkage clustering with the --eclust option. The default is 0.62.

OPTIONS CONTROLLING E-VALUE CALIBRATION

The location parameters for the expected score distributions for MSV filter scores, Viterbi filter scores, and Forward scores require three short random sequence simulations.

--EmL <n>
  Sets the sequence length in simulation that estimates the location parameter mu for MSV filter E-values. Default is 200.

--EmN <n>
  Sets the number of sequences in simulation that estimates the location parameter mu for MSV filter E-values. Default is 200.

--EvL <n>
  Sets the sequence length in simulation that estimates the location parameter mu for Viterbi filter E-values. Default is 200.

--EvN <n>
  Sets the number of sequences in simulation that estimates the location parameter mu for Viterbi filter E-values. Default is 200.

--EfL <n>
  Sets the sequence length in simulation that estimates the location parameter tau for Forward E-values. Default is 100.

--EfN <n>
  Sets the number of sequences in simulation that estimates the location parameter tau for Forward E-values. Default is 200.

--Eft <x>
  Sets the tail mass fraction to fit in the simulation that estimates the location parameter tau for Forward evalues. Default is 0.04.

OTHER OPTIONS

--mpi Run as a parallel MPI program. Each alignment is assigned to a MPI worker node for construction. (Therefore, the maximum parallelization cannot exceed the number of alignments in the input msafile.) This is useful when building large profile libraries. This option is only available if optional MPI capability was enabled at compile-time.

--informat <s>
  Declare that the input msafile is in format <s>. Currently the accepted multiple alignment sequence file formats only include Stockholm and SELEX. Default is to autodetect the format of the file.

--seed <n>
  Seed the random number generator with <n>, an integer >= 0. If <n> is nonzero, any stochastic simulations will be reproducible; the same command will give the same results. If <n> is 0, the random number generator is seeded arbitrarily, and stochastic simulations will vary from run to run of the same command. The default seed is 42.

--laplace Experimental only: use a Laplace +1 prior in place of the default mixture Dirichlet prior.

--stall
  For debugging MPI parallelization: arrest program execution immediately after start, and wait for a debugger to attach to the running process and release the arrest.

SEE ALSO

See hmmer(1) for a master man page with a list of all the individual man pages for programs in the HMMER package.

For complete documentation, see the user guide that came with your HMMER distribution (Userguide.pdf); or see the HMMER web page (@HMMER_URL@).

COPYRIGHT

@HMMER_COPYRIGHT@
@HMMER_LICENSE@

For additional information on copyright and licensing, see the file called COPYRIGHT in your HMMER source distribution, or see the HMMER web page (@HMMER_URL@).

AUTHOR

Eddy/Rivas Laboratory
Janelia Farm Research Campus
19700 Helix Drive
Ashburn VA 20147 USA
http://eddylab.org

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