FIG. 3.

Overexpression of SPT16 and overexpression of CTF4 have opposite effects on the pol1-1 mutant phenotype. (A) Overexpression of SPT16 suppresses the thermosensitivity of the pol1-1 mutant. Suppressor screening with a YEp24 base genomic library reveals that three clones can rescue temperature sensitivity of the pol1-1 mutant, clones 52 and 55 contain full-length POL1, and clone 59 contains full-length SPT16. (B) Overexpression of CTF4 exacerbates the thermosensitivity phenotype of the pol1-1 mutant. Suppression of the pol1-1 mutant by SPT16 is allele specific. Overexpression of either SPT16 or CTF4 does not suppress the thermosensitivity of the pol1-17 mutant, which contains a mutation of Thr¹⁰⁰⁴ to Ile.