Table 2.
α2p/Mcm1 sites mediate donor preference
| Strain
|
Allelea
|
Donor selectionb
|
|||
|---|---|---|---|---|---|
| in a cells
|
in α cells
|
||||
|
HML
|
HMR
|
HMR
|
HML
|
||
| Y2201 | wild type | 81% (152) | 13% (24) | 95% (239) | 2% (6) |
| Y2388 | dps1Δ | 68% (13) | 26% (5) | 84% (16) | 11% (2) |
| Y2389 | dps2Δ | 86% (18) | 10% (2) | 100% (28) | 0% (0) |
| Y2390 | dps1Δ dps2Δ | 30% (7) | 26% (6) | 75% (46) | 7% (4) |
| Y2391 | dps1–α2Δ | 95% (21) | 0% (0) | 70% (28) | 23% (9) |
| Y2392 | dps2–α2Δ | 87% (26) | 3% (1) | 90% (18) | 5% (1) |
| Y2393 | dps1–α2Δ dps2–α2Δ | 79% (30) | 5% (2) | 23% (9) | 55% (22) |
| Y2394 | dps1Δ–dps2Δ [DPS1 DPS2] | 40% (4) | 50% (5) | 61% (17) | 4% (1) |
(dps1Δ) Substitution of the sequence GGATCC for the 31 bp of chromosome III from position 29,194 to 29,224; (dps2Δ) substitution of the sequence GGATCC for the 31 bp of chromosome III from position 30,580 to 30,610; (dps1–α2Δ, dps2–α2Δ) sequences shown in Table 1. Strain Y2394 consists of strain Y2390 containing a centromeric plasmid carrying the 5.33-kb BamHI fragment spanning DPS1 and DPS2.
Donor preference was determined as described in Materials and Methods by examining the predominant allele at MAT in colonies derived from individual spores of the indicated cell type with the designated inversion obtained following dissection of the indicated strain. Numbers in parentheses are the absolute number of spore clones that had selected the designated donor during mating type interconversion. Only those colonies that gave a single predominant MAT allele are listed. The remainder for each strain represents colonies in which both donor alleles were represented essentially equally in the spore clone.