TABLE 2.
Summary of phenotypes observed for indicated histone alleles
| Phenotypesa | H2A alleles | H2B alleles |
|---|---|---|
| Loss of telomeric silencing (LTS) | R18A | R75A; R75K; R75L; R75M; K89A; R95A; R95K; K111Q; R119K; K123A; K123R; K123Q |
| Increase of telomeric silencing (ITS) | R102A; R102K | |
| Loss of rDNA silencing (LRS) | K21A; R75A; R102A; R102K; K111R; R119K; K123A; K123R; K123Q | |
| Increase of rDNA silencing (IRS) | R18A; R36A; K75R; R78K; K96A; K119Q | K6Q; K11A; K11Q; K16A; K16Q; K34A; K34Q; K46A; K46Q; K89A; K89R; K89Q; R95A; R95K |
| Sensitive to HU | K76A; K76Q; R78A | 111Q; K123A; K123R; K123Q |
| Sensitive to MMS | R18A; K76A; K76Q; R78A | |
| Sensitive to CPT | R78A | |
| Temperature sensitivity (39°) | R18A; K76A; K76Q; R78A; R78K | R95A; R102K; R119K; K123A; K123R; K123Q |
Residues covered in this test include H2A: K4, K7, K13, R18, R36, K75, K76, R78, K96, K119, K123, K126 and H2B: K3, K6, K11, K16, K21, K22, K34, K46, R75, K88, K89, R95, R102, K111, R119, K123. Each lysine was mutated to alanine, arginine, and glutamine and each arginine was mutated to lysine and glutamine. H2B K75 was also mutated to leucine and methionine. The mutants were analyzed and their phenotypes were compared to wild type and scored arbitrarily.
a
Other phenotypes tested include sensitivity to 6-azauracil (6-AU), benomyl, UV irradiation, and temperature sensitivity at 37° and 16°, which none of the mutants have.