Figure 2.

RLS extension in rho⁰ strains lacking SAGA or SLIK. (A) Deletion of ADA2, a core component of SAGA/SLIK. Mean RLS are 19.9, 25.6, and 13.8, for rho⁺, rho⁰, and rho⁰ ada2Δ strains, respectively. Lifespans for the first and second strain and for the second and third strain are significantly different (P = 0.009 and P < 0.001, respectively). (B) Elimination of both SLIK and SAGA in rho⁰ cells by removal of the common component Spt7. Mean RLS are 19.5, 24.7, and 12.7, for rho⁺, rho⁰, and rho⁰ spt7Δ strains, respectively. Lifespans for the first and second strain and for the second and third strain are significantly different (P = 0.022 and P < 0.001, respectively). (C) Elimination of SLIK in rho⁰ cells by the S200 mutation in SPT7, which prevents the processing of this protein to allow SLIK formation and comparison to point mutations in the specific Pep4 cleavage site encompassed by S200. Mean RLS are 20.9, 25.8, 24.3, 24.1, and 27.2, for rho⁺, rho⁰, rho⁰ spt7 ^L1141V, rho⁰ spt7 ^L1142V, and rho⁰ spt7 ^S200 strains, respectively. Lifespans for the first and second strain are significantly different (P = 0.003). There is no significant difference between the lifespans of the second and the third, fourth, and fifth strains (P-values of 0.502, 0.43, and 0.466, respectively). (D) Elimination of SAGA by deletion of SPT8, which is a component of SAGA but not SLIK. Mean RLS are 18.5, 25.8, and 32.6, for rho⁺, rho⁰, and rho⁰ spt8Δ strains, respectively. Lifespans for the first and second strain and for the second and third strain are significantly different (each P < 0.001). (E) Combined elimination of SLIK and SAGA by the S200 mutation in SPT7 and the deletion of SPT8. The mean RLS for the rho⁺, rho⁰, rho⁰ spt7 ^S200, and rho⁰ spt8Δ spt7 ^S200 strains were 19.4, 25.5, 27.4, and 27.0, respectively. Lifespans for the first and second strains are significantly different (P = 0.006), but those for the second and third and second and fourth are not (P = 0.345 and P = 0.373, respectively). (F) Combined prevention of ERC accumulation by FOB1 deletion and elimination of SAGA and SLIK by SPT8 deletion and the spt7 ^S200 mutation, respectively. The mean RLS for the rho⁰, rho⁰ spt8Δ, rho⁰ fob1Δ, rho⁰ spt8Δ fob1Δ, and rho⁰ spt8Δ fob1Δ spt7 ^S200 strains are 25.0, 32.1, 30.6, 38.5, and 30.7, respectively. The differences in lifespan between the rho⁰ strain and all of the others were significant. Except for the triple mutant, the P-values are 0.005 or lower, while for the triple mutant, P = 0.026. There are no significant differences between the rho⁰ spt8Δ strain and the rho⁰ fob1Δ or the triple mutant (P-values of ≥0.419). However, the differences between the rho⁰ spt8Δ fob1Δ and the rho⁰ spt8Δ (P = 0.034) and the rho⁰ fob1Δ (P < 0.001) strains are significant, while those for the rho⁰ fob1Δ and the triple mutant are not (P = 0.862). YPK9 is the rho⁺ strain and YJR2 is its rho⁰ derivative.