A general suppressor of RNA polymerase I, II and III mutations in Saccharomyces cerevisiae.
A multicopy genomic library of Saccharomyces cerevisiae (strain FL100) was screened for its ability to suppress conditionally defective mutations altering the 31 kDa subunit (rpc31-236) or the 53 kDa subunit (rpc53-254/424) of RNA polymerase III. In addition to allele-specific suppressors, we identified seven suppressor clones that acted on both mutations and also suppressed several other conditional mutations defective in RNA polymerases I or II. All these clones harbored a complete copy of the SSD1 gene. The same pleiotropic suppression pattern was found with the dominant SSD1-v allele present in some laboratory strains of S. cerevisiae. SSD1-v was previously shown to suppress mutations defective in the SIT4 gene product (a predicted protein phosphatase subunit) or in the regulatory subunit of the cyclic AMP-dependent protein kinase. We propose that the SSD1 gene product modulates the activity (or the level) of the three nuclear RNA polymerases, possibly by altering their degree of phosphorylation.
Département de Biologie Cellulaire et Moléculaire, C.E.A. Centre d'Etudes de Saclay, Gif sur Yvette, France.
S
S
Stettler
N
N
Chiannilkulchai
S
S
Hermann-Le Denmat
D
D
Lalo
F
F
Lacroute
A
A
Sentenac
P
P
Thuriaux
D000483:Alleles; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D012318:RNA Polymerase I / Q000235:genetics*; D012319:RNA Polymerase II / Q000235:genetics*; D012320:RNA Polymerase III / Q000235:genetics*; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D013489:Suppression, Genetic
D005656:Fungal Proteins; D012319:RNA Polymerase II; D012318:RNA Polymerase I; D012320:RNA Polymerase III