markPeaks

This pacakge is written for annotating regions such as ChIPseq peaks, histone marks or simply a genomic regions with nearest genes. It is written with focus on compact genomes such fungi and bacteria where intergenic space is very small (1-2kb) and ChIPseq peaks in tandem or divergent intergenic spaces or overlapping genes may result in false positive when existing methods like ChIPpeakAnno or ChIPseeker are used.

---

Install

library(devtools)
devtools::install_github("lakhanp1/markPeaks")

---

Usage

markPeaks uses TxDB package to annotate the peaks or genomic regions. For demonstration purpose, A. nidulans TxDB package is used in example below.

Install A. nidulans AnnotationHub packages like org.db, TxDb and BSgenome

## org.db
devtools::install_github(
  "lakhanp1/fungal_resources/A_nidulans/org.Anidulans.FGSCA4.eg.db",
  upgrade = "never")
  
## TxDb
devtools::install_github(
  "lakhanp1/fungal_resources/A_nidulans/TxDb.Anidulans.FGSCA4.AspGD.GFF",
  upgrade = "never")
  
## BSgenome
devtools::install_github(
  "lakhanp1/fungal_resources/A_nidulans/BSgenome.Anidulans.FGSCA4.AspGD",
  upgrade = "never")

Annotate peaks from narrowPeak file generated by MACS2

suppressPackageStartupMessages(library(markPeaks))
suppressPackageStartupMessages(library(TxDb.Anidulans.FGSCA4.AspGD.GFF))
suppressPackageStartupMessages(library(org.Anidulans.FGSCA4.eg.db))

txDb <- TxDb.Anidulans.FGSCA4.AspGD.GFF

file_peaks <- system.file("data/test_sample.withCtrl_peak.narrowPeak", package = "markPeaks")
file_output <- "test_sample.withCtrl_peak.narrowPeak.annotation.tab"

#####################################################################
############################
#### Optional features #####
############################
## optional feature 1: exclude peaks overlapping with blacklist regions from annotation
## A. nidulans ChIPseq blacklist regions file. This file has regions in A. nidulans genome which show
## abnormal ChIPseq signal.
file_blacklist <- here::system.file("data", "A_nidulans_FGSC_A4.blacklist_regions.bed", package = "markPeaks")

## optional feature 2: exclude genes coding for tRNA, snRNA etc from annotation
txInfo <- suppressMessages(
  AnnotationDbi::select(
    x = txDb, keys = AnnotationDbi::keys(x = txDb, keytype = "TXID"),
    columns = c("GENEID", "TXNAME", "TXTYPE"), keytype = "TXID")) %>%
  dplyr::mutate(TXID = as.character(TXID)) %>%
  dplyr::rename(geneId = GENEID, txName = TXNAME, txType = TXTYPE)

txInfo <- dplyr::filter(txInfo, !txType %in% c("tRNA", "rRNA", "snRNA", "snoRNA")) %>% 
  dplyr::filter(!grepl(pattern = "uORF", x = geneId))

############################
####  peak annotation  #####
############################

## Annoate the peaks and store data in 
peakAn <- markPeaks::annotate_peaks(
  peakFile = file_peaks,
  txdb = txDb,
  txIds = txInfo$TXID,                      ## optional arg
  fileFormat = "narrowPeak",
  promoterLength = 500,
  upstreamLimit = 1000,
  bidirectionalDistance = 1000,
  includeFractionCut = 0.7,
  bindingInGene = FALSE,
  insideSkewToEndCut = 0.7,
  blacklistRegions = file_blacklist,        ## optional arg
  removePseudo = TRUE,
  output = file_output                      ## optional arg
)

---

License

GPL V2