Fig. 7: A proposed model for the role of m6A in L1 replication and evolution.
From: L1 retrotransposons exploit RNA m6A modification as an evolutionary driving force
Full-length young L1s RNA have m6A in 5′ UTR A332 residue (lower part of scheme, m6A in red circle and m6A-gain mutation at T333C in red). 5′ UTR m6A cluster recruits eIF3 complex (green) and promotes translation of L1 ORF1p (yellow). Increased L1 ORF1p synthesis leads efficient production of L1 ribonucleotide particle (RNP) formation with its parental mRNA (line with poly A) and the reverse transcriptase, L1 ORF2p (magenta). The L1 RNP enters the nucleus and then generate the progeny through insertion of its cDNA. Old L1s with no A332 m6A motif have lower efficiency of translation and replication than those of A332 m6A-positive L1s (upper part of scheme). Since the A332 m6A motif first appeared ~12 million years ago, m6A-stimulated L1 replication has allowed m6A-positive L1s to survive during evolution, but made old L1s out of competition.
