Lorentz A, Heim L, Schmidt H
Institut für Genetik, Technische Universität Braunschweig, FRG.
Mol Gen Genet. 1992 Jun;233(3):436-42. doi: 10.1007/BF00265441.
The products of 11 switching (swi) genes are required for efficient mating-type (MT) switching in homothallic (h90) strains of Schizosaccharomyces pombe. The MT region of h90 comprises three cassette genes: the expression site mat1:1 and two silent loci, mat2:2 and mat3:3. Besides reducing MT switching, the swi6 mutation leads to deletions in the MT region caused by intrachromosomal cross-overs between two paired cassettes. These deletions only arise if DNA double-strand breaks are present at mat1:1, which initiate MT switching. Furthermore, swi6 allows meiotic recombination in the K region, a region of 16 kb between mat2:2 and mat3:3; in wild-type strains no recombination occurs in K. swi6 also allows the simultaneous expression of two different cassettes in the same haploid cell. Thus swi6 may have an influence on the general chromatin structure in the MT region.
在粟酒裂殖酵母同宗配合（h90）菌株中，高效的交配型（MT）转换需要11个转换（swi）基因的产物。h90的MT区域包含三个盒式基因：表达位点mat1:1和两个沉默位点mat2:2和mat3:3。除了减少MT转换外，swi6突变还会导致MT区域因两个配对盒式基因之间的染色体内交叉而出现缺失。只有当mat1:1处存在DNA双链断裂（引发MT转换）时，这些缺失才会出现。此外，swi6允许在K区域（mat2:2和mat3:3之间16 kb的区域）进行减数分裂重组；在野生型菌株中，K区域不发生重组。swi6还允许在同一单倍体细胞中同时表达两个不同的盒式基因。因此，swi6可能会对MT区域的一般染色质结构产生影响。
