Recombination in the λ repressor gene: evidence that very short patch (VSP) mismatch correction restores a specific sequence
- 1 June 1985
- journal article
- research article
- Published by Springer Nature in Molecular Genetics and Genomics
- Vol. 199 (3), 465-470
- https://doi.org/10.1007/bf00330759
Abstract
The mutation am6 in the cI gene of bacteriophage λ is identified as a C→T transition in a 5′CC T A GG sequence. In four-factor crosses of am6 with nearby mutations in cI, the frequencies of cI+ recombinants are much higher than expected from the physical distances. A very short patch (VSP) mismatch repair system is presumed to recognize am6/am + mispairs in the heteroduplexes that accompany recombination between the outside markers. Mutation am6 is corrected to am +; correction of am + to am6 was not detected. Clear-plaque mutation 1-1 in cI is a T→C transition in a 5′CTTGG sequence, resulting in the sequence 5′CC T A GG. When 1-1 was crossed with nearby mutations in gene cI, there were no excess cI+ recombinants, which would result from repair of CCTGG (1-1) to CTTGG (cI+). However, in crosses of cI+ phages with mutation 1-1, there was an excess of cI- recombinants, indicating that cI+ was repaired to 1-1. Preferential repair does not require adenine or cytosine methylation: when repairing a mismatch, the VSP repair system apparently identifies specific mispaired bases by sequence alone.This publication has 28 references indexed in Scilit:
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