NORMAL GENOMIC

• Borneman AR, Hynes MJ, Andrianopoulos A
• An STE12 homolog from the asexual, dimorphic fungus Penicillium marneffei complements the defect in sexual development of an Aspergillus nidulans steA mutant.
• Genetics. 2001; 157: 1003-14
• Display abstract

• Penicillium marneffei is an opportunistic fungal pathogen of humans and the only dimorphic species identified in its genus. At 25 degrees P. marneffei exhibits true filamentous growth, while at 37 degrees P. marneffei undergoes a dimorphic transition to produce uninucleate yeast cells that divide by fission. Members of the STE12 family of regulators are involved in controlling mating and yeast-hyphal transitions in a number of fungi. We have cloned a homolog of the S. cerevisiae STE12 gene from P. marneffei, stlA, which is highly conserved. The stlA gene, along with the A. nidulans steA and Cryptococcus neoformans STE12alpha genes, form a distinct subclass of STE12 homologs that have a C2H2 zinc-finger motif in addition to the homeobox domain that defines STE12 genes. To examine the function of stlA in P. marneffei, we isolated a number of mutants in the P. marneffei-type strain and, in combination with selectable markers, developed a highly efficient DNA-mediated transformation procedure and gene deletion strategy. Deletion of the stlA gene had no detectable effect on vegetative growth, asexual development, or dimorphic switching in P. marneffei. Despite the lack of a detectable function, the P. marneffei stlA gene complemented the sexual defect of an A. nidulans steA mutant. In addition, substitution rate estimates indicate that there is a significant bias against nonsynonymous substitutions. These data suggest that P. marneffei may have a previously unidentified cryptic sexual cycle.

• Svetlov VV, Cooper TG
• Review: compilation and characteristics of dedicated transcription factors in Saccharomyces cerevisiae.
• Yeast. 1995; 11: 1439-84

• Mylin LM, Gerardot CJ, Hopper JE, Dickson RC
• Sequence conservation in the Saccharomyces and Kluveromyces GAL11 transcription activators suggests functional domains.
• Nucleic Acids Res. 1991; 19: 5345-50
• Display abstract

• Efficient transcription of many Saccharomyces cerevisiae genes requires the GAL11 Protein. GAL11 belongs to a class of transcription activator that lacks a DNA-binding domain. Such proteins are thought to activate specific genes by complexing with DNA-bound proteins. To begin to understand the domain structure-function relationships of GAL11 we cloned and sequenced a homologue from the yeast Kluyveromyces lactis, Kl-GAL11. The two predicted GAL11 proteins show high overall amino acid conservation and an unusual amino acid composition including 18% glutamine, 10% asparagine (S. cerevisiae) or 7% (K. lactis), and 8% proline (K. lactis) or 5% (S. cerevisiae) residues. Both proteins have runs of pure glutamines. Sc-GAL11 has glutamine-alanine runs but in Kl-GAL11 the alanines in such runs are replaced by proline and other residues. The primary sequence similarity is reflected in functional similarity since a gal11 mutation in K. lactis creates phenotypes similar to those seen previously in gal11-defective S. cerevisiae. In addition, Kl-GAL11 complements a gal11-defect in S. cerevisiae by partially restoring induction of GAL1 expression, growth on nonfermentable carbon sources, and phosphorylation of GAL4.