SUMMARY PARAGRAPH for FZF1
FZF1 encodes a non-essential constitutively-expressed transcription factor involved in sulfite metabolism which contains five zinc fingers of the Cys2His2 class, three of which are positioned in tandem at the N-terminus (1, 4, 5). The fourth and fifth zinc fingers follow after interruptions of 61 and 66 amino acids, respectively (1). The sole Fzf1p target identified thus far is SSU1, which encodes a plasma membrane sulfite pump (5). Fzf1p binds directly to the SSU1 promoter, and its first zinc finger region is absolutely required for DNA binding; the fourth and fifth zinc fingers appear to be dispensable for DNA binding (5).
Multicopy FZF1 suppresses the sulfite sensitive phenotype of grr1 strains, but not the glucose derepression or aberrant cell morphology. Multicopy FZF1 was also found to suppress the sensitivity of a number of other unrelated sulfite-sensitive mutants, but not that of ssu1 or met1 (4). Some specific mutations in FZF1 conferring sulfite resistance have been identified. A C to G transversion at position 538 causing the substitution of an aspartic acid for a histidine in the fourth zinc finger directly affects its structure, thereby conferring sulfite resistance (3). Also, cysteine 57 in wild-type Fzf1p was found to be replaced by tyrosine in the dominant Fzf1-4p, which also confers sulfite resistance. Cells expressing FZF1-4 accumulate less intracellular sulfite due to hyperactivation of SSU1 (2, 7).
Last updated: 2005-02-25