Provided by: hmmer_3.4+dfsg-2_amd64 
NAME
hmmscan - search sequence(s) against a profile database
SYNOPSIS
hmmscan [options] hmmdb seqfile
DESCRIPTION
hmmscan is used to search protein sequences against collections of protein profiles. For each sequence in
seqfile, use that query sequence to search the target database of profiles in hmmdb, and output ranked
lists of the profiles with the most significant matches to the sequence.
The seqfile may contain more than one query sequence. Each will be searched in turn against hmmdb.
The hmmdb needs to be press'ed using hmmpress before it can be searched with hmmscan. This creates four
binary files, suffixed .h3{fimp}.
The query seqfile may be '-' (a dash character), in which case the query sequences are read from a stdin
pipe instead of from a file. The hmmdb cannot be read from a stdin stream, because it needs to have
those four auxiliary binary files generated by hmmpress.
The output format is designed to be human-readable, but is often so voluminous that reading it is
impractical, and parsing it is a pain. The --tblout and --domtblout options save output in simple tabular
formats that are concise and easier to parse. The -o option allows redirecting the main output,
including throwing it away in /dev/null.
OPTIONS
-h Help; print a brief reminder of command line usage and all available options.
OPTIONS FOR CONTROLLING OUTPUT
-o <f> Direct the main human-readable output to a file <f> instead of the default stdout.
--tblout <f>
Save a simple tabular (space-delimited) file summarizing the per-target output, with one data line
per homologous target model found.
--domtblout <f>
Save a simple tabular (space-delimited) file summarizing the per-domain output, with one data line
per homologous domain detected in a query sequence for each homologous model.
--pfamtblout <f>
Save an especially succinct tabular (space-delimited) file summarizing the per-target output, with
one data line per homologous target model found.
--acc Use accessions instead of names in the main output, where available for profiles and/or sequences.
--noali
Omit the alignment section from the main output. This can greatly reduce the output volume.
--notextw
Unlimit the length of each line in the main output. The default is a limit of 120 characters per
line, which helps in displaying the output cleanly on terminals and in editors, but can truncate
target profile description lines.
--textw <n>
Set the main output's line length limit to <n> characters per line. The default is 120.
OPTIONS FOR REPORTING THRESHOLDS
Reporting thresholds control which hits are reported in output files (the main output, --tblout, and
--domtblout).
-E <x> In the per-target output, report target profiles with an E-value of <= <x>. The default is 10.0,
meaning that on average, about 10 false positives will be reported per query, so you can see the
top of the noise and decide for yourself if it's really noise.
-T <x> Instead of thresholding per-profile output on E-value, instead report target profiles with a bit
score of >= <x>.
--domE <x>
In the per-domain output, for target profiles that have already satisfied the per-profile
reporting threshold, report individual domains with a conditional E-value of <= <x>. The default
is 10.0. A conditional E-value means the expected number of additional false positive domains in
the smaller search space of those comparisons that already satisfied the per-profile reporting
threshold (and thus must have at least one homologous domain already).
--domT <x>
Instead of thresholding per-domain output on E-value, instead report domains with a bit score of
>= <x>.
OPTIONS FOR INCLUSION THRESHOLDS
Inclusion thresholds are stricter than reporting thresholds. Inclusion thresholds control which hits are
considered to be reliable enough to be included in an output alignment or a subsequent search round. In
hmmscan, which does not have any alignment output (like hmmsearch or phmmer) nor any iterative search
steps (like jackhmmer), inclusion thresholds have little effect. They only affect what domains get marked
as significant (!) or questionable (?) in domain output.
--incE <x>
Use an E-value of <= <x> as the per-target inclusion threshold. The default is 0.01, meaning that
on average, about 1 false positive would be expected in every 100 searches with different query
sequences.
--incT <x>
Instead of using E-values for setting the inclusion threshold, instead use a bit score of >= <x>
as the per-target inclusion threshold. It would be unusual to use bit score thresholds with
hmmscan, because you don't expect a single score threshold to work for different profiles;
different profiles have slightly different expected score distributions.
--incdomE <x>
Use a conditional E-value of <= <x> as the per-domain inclusion threshold, in targets that have
already satisfied the overall per-target inclusion threshold. The default is 0.01.
--incdomT <x>
Instead of using E-values, instead use a bit score of >= <x> as the per-domain inclusion
threshold. As with --incT above, it would be unusual to use a single bit score threshold in
hmmscan.
OPTIONS FOR MODEL-SPECIFIC SCORE THRESHOLDING
Curated profile databases may define specific bit score thresholds for each profile, superseding any
thresholding based on statistical significance alone.
To use these options, the profile must contain the appropriate (GA, TC, and/or NC) optional score
threshold annotation; this is picked up by hmmbuild from Stockholm format alignment files. Each
thresholding option has two scores: the per-sequence threshold <x1> and the per-domain threshold <x2>.
These act as if -T <x1> --incT <x1> --domT <x2> --incdomT <x2> has been applied specifically using each
model's curated thresholds.
--cut_ga
Use the GA (gathering) bit scores in the model to set per-sequence (GA1) and per-domain (GA2)
reporting and inclusion thresholds. GA thresholds are generally considered to be the reliable
curated thresholds defining family membership; for example, in Pfam, these thresholds define what
gets included in Pfam Full alignments based on searches with Pfam Seed models.
--cut_nc
Use the NC (noise cutoff) bit score thresholds in the model to set per-sequence (NC1) and per-
domain (NC2) reporting and inclusion thresholds. NC thresholds are generally considered to be the
score of the highest-scoring known false positive.
--cut_tc
Use the NC (trusted cutoff) bit score thresholds in the model to set per-sequence (TC1) and per-
domain (TC2) reporting and inclusion thresholds. TC thresholds are generally considered to be the
score of the lowest-scoring known true positive that is above all known false positives.
CONTROL OF THE ACCELERATION PIPELINE
HMMER3 searches are accelerated in a three-step filter pipeline: the MSV filter, the Viterbi filter, and
the Forward filter. The first filter is the fastest and most approximate; the last is the full Forward
scoring algorithm. There is also a bias filter step between MSV and Viterbi. Targets that pass all the
steps in the acceleration pipeline are then subjected to postprocessing -- domain identification and
scoring using the Forward/Backward algorithm.
Changing filter thresholds only removes or includes targets from consideration; changing filter
thresholds does not alter bit scores, E-values, or alignments, all of which are determined solely in
postprocessing.
--max Turn off all filters, including the bias filter, and run full Forward/Backward postprocessing on
every target. This increases sensitivity somewhat, at a large cost in speed.
--F1 <x>
Set the P-value threshold for the MSV filter step. The default is 0.02, meaning that roughly 2%
of the highest scoring nonhomologous targets are expected to pass the filter.
--F2 <x>
Set the P-value threshold for the Viterbi filter step. The default is 0.001.
--F3 <x>
Set the P-value threshold for the Forward filter step. The default is 1e-5.
--nobias
Turn off the bias filter. This increases sensitivity somewhat, but can come at a high cost in
speed, especially if the query has biased residue composition (such as a repetitive sequence
region, or if it is a membrane protein with large regions of hydrophobicity). Without the bias
filter, too many sequences may pass the filter with biased queries, leading to slower than
expected performance as the computationally intensive Forward/Backward algorithms shoulder an
abnormally heavy load.
OTHER OPTIONS
--nonull2
Turn off the null2 score corrections for biased composition.
-Z <x> Assert that the total number of targets in your searches is <x>, for the purposes of per-sequence
E-value calculations, rather than the actual number of targets seen.
--domZ <x>
Assert that the total number of targets in your searches is <x>, for the purposes of per-domain
conditional E-value calculations, rather than the number of targets that passed the reporting
thresholds.
--seed <n>
Set the random number seed to <n>. Some steps in postprocessing require Monte Carlo simulation.
The default is to use a fixed seed (42), so that results are exactly reproducible. Any other
positive integer will give different (but also reproducible) results. A choice of 0 uses an
arbitrarily chosen seed.
--qformat <s>
Assert that input seqfile is in format <s>, bypassing format autodetection. Common choices for
<s> include: fasta, embl, genbank. Alignment formats also work; common choices include:
stockholm, a2m, afa, psiblast, clustal, phylip. For more information, and for codes for some less
common formats, see main documentation. The string <s> is case-insensitive (fasta or FASTA both
work).
--cpu <n>
Set the number of parallel worker threads to <n>. The default is 0, meaning off (no thread-level
parallelization), because hmmscan is typically i/o bound and the extra overhead of our current
multithreaded implementation isn't worthwhile. You can also control this number by setting an
environment variable, HMMER_NCPU. There is also a master thread, so the actual number of threads
that HMMER spawns is at least <n>+1.
This option is not available if HMMER was compiled with POSIX threads support turned off.
--stall
For debugging the MPI master/worker version: pause after start, to enable the developer to attach
debuggers to the running master and worker(s) processes. Send SIGCONT signal to release the pause.
(Under gdb: (gdb) signal SIGCONT)
(Only available if optional MPI support was enabled at compile-time.)
--mpi Run under MPI control with master/worker parallelization (using mpirun, for example, or
equivalent). Only available if optional MPI support was enabled at compile-time.
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 (http://hmmer.org/).
COPYRIGHT
Copyright (C) 2023 Howard Hughes Medical Institute.
Freely distributed under the BSD open source license.
For additional information on copyright and licensing, see the file called COPYRIGHT in your HMMER source
distribution, or see the HMMER web page (http://hmmer.org/).
AUTHOR
http://eddylab.org
HMMER 3.4 Aug 2023 hmmscan(1)