Figure 1.

Activation of the retrograde response in rho⁰ strains lacking SAGA or SLIK. Activation of the retrograde response was assessed by comparing the CIT2 mRNA levels (relative to ACT1) by RT-qPCR in the rho⁺ strain YPK9 and its rho⁰ derivative YJR2. (A) Deletion of ADA2, a core component of SAGA/SLIK in rho⁰ cells. (B) 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. (C) Elimination of SAGA in rho⁰ cells by deletion of SPT8, which is a component of SAGA but not SLIK. (D) Elimination of both SLIK and SAGA in rho⁰ cells by the S200 mutation in SPT7 and the deletion of SPT8, respectively. (E) Elimination of both SLIK and SAGA in rho⁰ cells by removal of the common component Spt7.