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pqsfinder (version 1.0.2)

pqsfinder: Identificate potential quadruplex forming sequences.

Description

Function for identification of all potential intramolecular quadruplex patterns (PQS) in DNA sequence.

Usage

pqsfinder(subject, strand = "*", max_len = 50L, min_score = 42L,
  run_min_len = 3L, run_max_len = 11L, loop_min_len = 0L,
  loop_max_len = 30L, max_bulges = 3L, max_mismatches = 2L,
  max_defects = 3L, tetrad_bonus = 45L, bulge_penalty = 20L,
  mismatch_penalty = 31L, loop_mean_factor = 1, loop_sd_factor = 1,
  run_re = "G{1,5}.{0,5}G{1,5}", custom_scoring_fn = NULL,
  use_default_scoring = TRUE, verbose = FALSE)

Arguments

subject
DNAString object.
strand
Strand specification. Allowed values are "+", "-" or "*", where the last one represents both strands. Implicitly, the input DNAString object is assumed to encode the "+" strand.
max_len
Maximal lenth of PQS.
min_score
Minimal PQS score.
run_min_len
Minimal length of quadruplex run.
run_max_len
Maximal length of quadruplex run.
loop_min_len
Minimal length of quadruplex loop.
loop_max_len
Maxmimal length of quadruplex loop.
max_bulges
Maximal number of runs with bulge.
max_mismatches
Maximal number of runs with mismatch.
max_defects
Maximum number of defects in total (max_bulges + max_mismatches).
tetrad_bonus
Score bonus for one complete G tetrade.
bulge_penalty
Penalization for a bulge in quadruplex run.
mismatch_penalty
Penalization for a mismatch in tetrad.
loop_mean_factor
Penalization factor of loop lengths mean.
loop_sd_factor
Penalization factor of loop lengths standard deviation.
run_re
Regular expression specifying one run of quadruplex.
custom_scoring_fn
Custom quadruplex scoring function. It takes the following 10 arguments: subject - Input DNAString object, score - implicit PQS score, start - PQS start position, width - PQS width, loop_1 - start pos. of loop #1, run_2 - start pos. of run #2, loop_2 - start pos. of loop #2, run_3 - start pos. of run #3, loop_3 - start pos. of loop #3, run_4 - start pos. of run #4. Return value of the function has to be new score represented as a single integer value. Please note that if use_default_scoring is enabled, the custom scoring function is evaluated AFTER the default scoring system but ONLY IF the default scoring system resulted in non-zero score (for performance reasons). On the other hand, when use_default_scoring is disabled, custom scoring function is evaluated on every PQS.
use_default_scoring
Enables default internal scoring system. This option is particularly useful in case you intend to radically change the default behavior and specify your own scoring function. By disabling the default scoring you will get a full control above the underlying detection algorithm.
verbose
Enables detailed output. Turn it on if you want to see all possible PQS found at each positions and not just the best one. It is highly recommended to use this option for debugging custom quadruplex scoring function. Each PQS is reported on separate row in the following format: start cnt pqs_sequence score, where start is the PQS starting position, pqs_sequence shows the PQS sequence structure with each run surrounded by square brackets and score is the score assigned to the particular PQS by all applied scoring functions.

Value

Examples

Run this code
pv <- pqsfinder(DNAString("CCCCCCGGGTGGGTGGGTGGGAAAA"))

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