Get Confident Peaks From ChIP_SR replicates

This workflow takes as input SR BAM from ChIP-seq. It calls peaks on each replicate and intersect them. In parallel, each BAM is subsetted to smallest number of reads. Peaks are called using all subsets combined. Only peaks called using a combination of all subsets which have summits intersecting the intersection of at least x replicates will be kept.

  • Author(s):
  • Lucille Delisle
  • Release: 1.2
  • License: MIT
  • UniqueID: f71eee25-8402-41da-8284-5298656ab379

Consensus peaks Workflow

The goal of this workflow is to get a list of confident peaks with summits from n replicates.

Inputs dataset

  • The workflow needs a single input which is a list of datasets with n BAM where PCR duplicates have been removed (the workflow also works for nested list if you have multiple conditions each with multiple replicates).

Inputs values

  • Minimum number of overlap: Minimum number of replicates into which the final summit should be present.
  • effective_genome_size: this is used by MACS2 and may be entered manually (indications are provided for heavily used genomes).
  • bin_size: this is the bin sized used to compute the average of normalized profiles. Large values will allow to have a smaller output file but with less resolution while small values will increase computation time and size of the output file to produce a more resolutive bigwig.

Strategy summary

Here is a generated example to highlight the strategy: strategy

Processing

  • The workflow will:
    • first part:
      • call peaks and compute normalized coverage on each BAM individually
      • average normalized profiles
      • compute the intersection between all peaks and filter when at least x replicate overlaps
    • second part:
      • subset all BAM to get the same number of reads
      • call peaks on all subsetted BAM combined
    • finally, keep only peaks from the second part that have summits overlapping the filtered intersection of the first part.