Model for the generation and growth of CRM-derived tandem repeat arrays. a. Sequential illegitimate recombinations between short regions of homology, as shown by two deletion events, Δ1 between the trinucleotides TGA shown in blue font and Δ2 between trinucleotides GAT shown in red font above the full length retrotransposon schematic at the top (not to scale), can generate an LTR-UTR~LTR structure (a prerequisite for formation of CRM1TR tandem arrays) containing the characteristic UTR~LTR junction between CRM1TR repeat monomers. b. Growth of CRM-derived tandem repeat arrays by non-allelic/interlocus gene conversion. A double strand break in the downstream LTR of LTR-UTR~LTR in one of the chromatids is repaired using the non-allelic LTR of the LTR-UTR~LTR structure on the sister chromatid (bottom) by the standard double strand break (DSB) repair model. The details of the repair (processing of both strands at the site of DSB to generate 3’ overhangs, sister chromatid invasion by the 3’ overhangs, branch migration and resolution of the two Holliday Junctions) are not shown. *Figure not to scale: LTR (red), UTR (yellow), polyprotein (blue).
Sharma et al. BMC Genomics 2013 14:142 doi:10.1186/1471-2164-14-142