Phenotypic analysis of genes encoding yeast zinc cluster proteins

Abstract

Zinc cluster proteins (or binuclear cluster proteins) possess zinc fingers of the Zn(II)2Cys6-type involved in DNA recognition as exemplified by the well-characterized protein Gal4p. These fungal proteins are transcriptional regulators of genes involved in a wide variety of cellular processes including metabolism of compounds such as amino acids and sugars, as well as control of meiosis, multi-drug resistance etc. The yeast (Saccharomyces cerevisiae) sequencing project has allowed the identification of additional zinc cluster proteins for a total of 54. However, the role of many of these putative zinc cluster proteins is unknown. We have performed phenotypic analysis of 33 genes encoding (putative) zinc cluster proteins. Only two members of the GAL4 family are essential genes. Our results show that deletion of eight different zinc cluster genes impairs growth on non-fermentable carbon sources. The same strains are also hypersensitive to the antifungal calcofluor white suggesting a role for these genes in cell wall integrity. In addition, one of these strains (YFL052W) is also heat sensitive on rich (but not minimal) plates. Thus, deletion of YFL052W results in sensitivity to a combination of low osmolarity and high temperature. In addition, six strains are hypersensitive to caffeine, an inhibitor of the MAP kinase pathway and phosphodiesterase of the cAMP pathway. In conclusion, our analysis assigns phenotypes to a number of genes and provides a basis to better understand the role of these transcriptional regulators.

Figure 1

Growth on non-fermentable carbon source of selected strains. Wild-type and deletion strains were grown overnight in YEP–glucose, washed, serially diluted and spotted on YEP–glucose or YEP–glycerol plates, as indicated. Wild-type strain is FY73. For more details, see Materials and Methods.

Figure 2

Caffeine sensitivity in YHR178W (STB5) deleted strain. Wild-type (BY4742) and deletion strain (BT, Table 1) were grown overnight in YPD, washed, serially diluted and spotted on YPD plates either with or without 0.15% caffeine.

Figure 3

Calcofluor white sensitivity in deletion strains. Wild-type (FY73) and deletion strains were grown overnight in YPD, washed, serially diluted and spotted on YPD plates with or without 70 µg/ml calcofluor white. ORF deletions are indicated on left.