Table 4.
Dosage effects of kinetochore protein genes on the bir1Δ chromosome-loss phenotype
| Plasmid | Red colonies | Half-sectored colonies | Total colonies | Loss rate/ cell division* | Fold decrease† |
|---|---|---|---|---|---|
| YEp24 | 48 | 19 | 4,794 | 4.00 × 10−3 | 1.0 |
| YEp24-BIR1 | 3 | 1 | 13,422 | 7.45 × 10−5 | 53.7 |
| YEp24-BIR1 (N552) | 9 | 4 | 2,848 | 1.41 × 10−3 | 2.8 |
| YEp24-BIR1 (C405) | 3 | 1 | 14,108 | 7.09 × 10−5 | 56.5 |
| YEp24-NDC10 | 0 | 1 | 13,540 | 7.39 × 10−5 | 54.2 |
| YEp24-CEP3 | 75 | 3 | 2,955 | 1.04 × 10−3 | 3.8 |
| YEP24-CTF13 | 24 | 6 | 5,200 | 1.16 × 10−3 | 3.5 |
| YEP24-SKP1 | 24 | 12 | 2,279 | 5.32 × 10−3 | 0.8 |
The bir1Δ mutant (YHY402) was transformed with a high-copy plasmid YEp24 (2 μm, URA3) or YEp24 carrying BIR1, NDC10, CEP3, CTF13, or SKP1. In addition to the complete BIR1 ORF, a 1.7-kb fragment that expresses the N-terminal 552 amino acids of Bir1p or a 1.2-kb fragment that expreses the C-terminal 405 amino acids of Bir1p was also subcloned into YEp24 and tested for the ability to complement the bir1 null mutation. The colony color sectoring assay was performed as described in Table 2.
Loss rate/cell division = half-sectored colonies/(total colonies − red colonies).
† Fold decrease = loss rate/cell division of bir1Δ cells carrying YEp24 divided by loss rate/cell division of bir1Δ cells containing each of the indicated plasmids.