DigestDNA {DECIPHER} | R Documentation

## Simulate Restriction Digestion of DNA

### Description

Restriction enzymes can be used to cut double-stranded DNA into fragments at specific cut sites. `DigestDNA` performs an in-silico restriction digest of the input DNA sequence(s) given one or more restriction sites.

### Usage

    DigestDNA(sites,
              myDNAStringSet,
              type = "fragments",
              strand = "both")

### Arguments

`sites` | A character vector of DNA recognition sequences and their enzymes' corresponding cut site(s).
`myDNAStringSet` | A `DNAStringSet` object or character vector with one or more sequences in 5' to 3' orientation.
`type` | Character string indicating the type of results desired. This should be (an abbreviation of) either `"fragments"` or `"positions"`.
`strand` | Character string indicating the strand(s) to cut. This should be (an abbreviation of) one of `"both"`, `"top"`, or `"bottom"`. The top strand is defined as the input DNAStringSet sequence, and the bottom strand is its reverse complement.

### Details

In the context of a restriction digest experiment with a known DNA sequence, it can be useful to predict the expected DNA fragments in-silico. Restriction enzymes make cuts in double-stranded DNA at specific positions near their recognition site. The recognition site may be somewhat ambiguous, as represented by the `IUPAC_CODE_MAP`. Cuts that occur at different positions on the top and bottom strands result in sticky-ends, whereas those that occur at the same position result in fragments with blunt-ends. Multiple restriction `sites` can be supplied to simultaneously digest the DNA. In this case, `sites` for the different restriction enzymes may be overlapping, which could result in multiple close-proximity cuts that would not occur experimentally. Also, note that cut sites will not be matched to non-`DNA_BASES` in `myDNAStringSet`.

### Value

`DigestDNA` can return two `type`s of results: cut `positions` or the resulting DNA `fragments` corresponding to the `top`, `bottom`, or `both` strands. If `type` is `"positions"` then the output is a list with the cut location(s) in each sequence in `myDNAStringSet`. The cut location is defined as the position after the cut relative to the 5'-end. For example, a cut at `6` would occur between positions 5 and 6, where the respective strand's 5' nucleotide is defined as position 1.

If `type` is `"fragments"` (the default), then the result is a `DNAStringSetList`. Each element of the list contains the `top` and/or `bottom` strand fragments after digestion of `myDNAStringSet`, or the original sequence if no cuts were made. Sequences are named by whether they originated from the `top` or `bottom` strand, and list elements are named based on the input DNA sequences. The `top` strand is defined by `myDNAStringSet` as it is input, whereas the `bottom` strand is its reverse complement.

### Author(s)

Erik Wright eswright@pitt.edu

### See Also

`DesignSignatures`, `RESTRICTION_ENZYMES`

### Examples

    # digest hypothetical DNA sequences with BamHI
    data(RESTRICTION_ENZYMES)
    site <- RESTRICTION_ENZYMES[c("BamHI")]
    dna <- DNAStringSet(c("AAGGATCCAA", "GGGATCAT"))
    dna # top strand
    reverseComplement(dna) # bottom strand
    names(dna) <- c("hyp1", "hyp2")
    d <- DigestDNA(site, dna)
    d # fragments in a DNAStringSetList
    unlist(d) # all fragments as one DNAStringSet

    # Restriction digest of Yeast Chr. 1 with EcoRI and EcoRV
    data(yeastSEQCHR1)
    sites <- RESTRICTION_ENZYMES[c("EcoRI", "EcoRV")]
    seqs <- DigestDNA(sites, yeastSEQCHR1)
    seqs[[1]]

    pos <- DigestDNA(sites, yeastSEQCHR1, type="positions")
    str(pos)

[Package DECIPHER version 2.8.1 Index]