TABLE 1.
Summary of tlc1 mutant phenotypesa
| TLC1 allele | Template sequenceb | Fold reduction in Rap1p binding | Telomere length (bp) | Telomerase activity | Senescence |
|---|---|---|---|---|---|
| TLC1 | ACCCA | 1 | 350 | + | No |
| tlc1-478gug | gugCA | >300c | 150c | +c | No |
| tlc1-476gug | ACgug | >300c | *c | −c | Yes |
| tlc1-476gCA | ACgCA | >300 | 3,000 | + | No |
| tlc1-476CuA | ACCuA | 14 | 800 | + | No |
| tlc1-476CCg | ACCCg | 4 | 250 | + | No |
| tlc1-476Cug | ACCug | >300 | 250 | + | No |
| tlc1-476gCg | ACgCg | >300 | *200 | + | Slow |
| tlc1-476guA | ACguA | >300 | *200 | + | Slow |
a
Various mutant alleles of TLC1 are shown, along with the positions of the mutated residues (lowercase) in the TLC1 RNA and the effects that each mutation has on Rap1p binding in vitro, on telomere length in vivo, and on telomerase activity in vitro. An asterisk indicates that telomere length was not stably maintained by the mutant enzyme; in the case of the two senescent double mutants (gCg and guA), the telomere length at which the strain senesced is also given.
b
From positions 478 to 474.
c
Data reported previously (34).