PRDM9 directs recombination hotspots to prevent competition with meiotic transcription

PRDM9 drives recombination hotspots in some mammals, including mice and apes. Non-functional orthologs of PRDM9 are present in a wide variety of vertebrates, but why it is functionally maintained in some lineages is not clear. One possible explanation is that PRDM9 plays a role in ensuring that meiosis is successful. During meiosis, available DNA may be a limiting resource given the tight packaging of chromosomes and could lead to competition between two key processes: meiotic transcription and recombination. Here we explore this potential competition and the role that PRDM9 might play in their interaction. Leveraging existing mouse genomic data, we use resampling schemes that simulate shuffled features along the genome and models that account for the rarity of features in the genome, to test if PRDM9 influences interactions between recombination hotspots and meiotic transcription in a whole genome framework. We also explored possible DNA sequence motifs associated to clusters of hotspots not tied to transcription or PRDM9. We find evidence of competition between meiotic transcription and recombination, with PRDM9 appearing to relocate recombination to avoid said conflict. We also find that retrotransposons may be playing a role in directing hotspots in the absence of other factors.