I am trying to rename the seqlevels in an interactionSet object. The syntax for common GRanges don't work in an interaction set. Any ideas how to make it work then?

library(GenomicRanges)

gr <- GRanges(rep(c("chr2", "chr3", "chrM"), 2), IRanges(1:6, 10))

 index.epistasis <- expand.grid(seq_len(length(gr)), seq_len(length(gr)))

gr.interactions <- InteractionSet::GInteractions(index.epistasis$Var1, index.epistasis$Var2, gr)

seqlevels(gr) <- sub("chrM", "chrMit", seqlevels(gr)) ## works

seqlevels(gr.interactions) <- sub("chrM", "chrMit", seqlevels(gr.interactions)) ## error

Error in GenomeInfoDb:::makeNewSeqnames(x, new2old = new2old, seqlevels(value)) :
  when 'new2old' is NULL, the first elements in the
  supplied 'seqlevels' must be identical to 'seqlevels(x)'

It doesn't work because I haven't gotten around to adding seqlevels<-. The current workaround would be:

seqlevels(regions(gr.interactions)) <- sub("chrM", "chrMit", seqlevels(regions(gr.interactions)))