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DNA inversions between short inverted repeats in Escherichia coli
M A Schofield1, R Agbunag, J H Miller
1Molecular Biology Institutes, University of California, Los Angeles 90024.
Abstract:
Using site-specific mutagenesis in vitro, we have constructed Escherichia coli strains that allow the detection of the inversion of an 800-bp segment in the lac region. The invertible segment is bounded by inverted repeats of either 12 or 23 bp. Inversions occurring at these inverted repeats will restore the Lac+ phenotype. Inversions can be detected at both short homologies at frequencies ranging from 0.5 x 10(-8) to 1 x 10(-7). These events, which have been verified by DNA sequence analysis, are reduced up to 1000-fold in strains deficient for either RecA, RecB or RecC. They are not reduced in strains deficient in the RecF, J pathway. These results show that the RecB,C,D system can mediate rearrangements at short sequence repeats, and probably plays a major role in cellular rearrangements.