A NON-HYPERVARIABLE HUMAN MINISATELLITE STRONGLY STIMULATES IN-VITRO INTRAMOLECULAR HOMOLOGOUS RECOMBINATION

Several features indicate that the low polymorphic human minisatellite MsH42 region could be involved in, recombination. It contains differe nt well-known recombination motifs, is able to generate single-strande d loops and is specifically recognized by nuclear proteins. These char acteristics led us to investigate the possible recombinogenic activity of the MsH42 region in terms of intramolecular recombination. We cons tructed two plasmids, one of them carrying two copies of the minisatel lite region and the other; one containing sequences upstream of this r epetitive region. We showed that MsH42 strongly stimulates intramolecu lar in vitro recombination, similar to 22 times more than the control sequence, solely when the source of biological extract is mouse testes , suggesting that MsH42 could be a hotspot involved in meiotic recombi nation. Furthermore, there is a direct relationship between the freque ncy of equal crossovers and the enhancement of recombination. Interest ingly, the third repeat of the minisatellite array is always involved in the resolution of unequal crossovers leading to minisatellite short ening. As far as we know, our results provide the first evidence that a non-hypervariable minisatellite can enhance homologous recombination . (C) 1998 Academic Press Limited.