ABSTRACT
Transcription factor Ace1 from Saccharomyces cerevisiae regulates the expression of target genes when the copper concentration reaches 200 ìÌ levels. We are studying the ortholog of Ace1 from fungus Phanerochaete chrysosporium PcACE1, isolated by complementation in yeast. In this report we show the localization of the transactivation region of PcACE1. Different PcACE1 fragments were ligated in frame to the GAL4 DNA-binding domain by site-directed mutagenesis in a suitable yeast expression vector. Transformation of an appropriate Saccharomyces cerevisiae strain was used as host. This strain contains the fusion GAL1:lacZ in its genome under the control of promoter sequences recognized by GAL4. Finally, we measured â-galactosidase activity in each yeast clone. The activation of the reporter gene is proportional to the transactivation capacity of the transcription factor PcACE1. The results obtained indicate that PcACE1 transactivation domain is located in the carboxy terminal half and contains an array of cysteines in the form of Cys-X-Cys and Cys-X2-Cys and a 60% of Ser. Therefore, these results show that this type of Cys motif can function as transcription activating domain not only in transcription factors that respond to minimal copper concentrations but also in those that respond to high copper concentrations. This is the first transactivation domain reported in a basidiomycete fungus.
Subject(s)
Gene Expression Regulation, Fungal/genetics , Phanerochaete/genetics , Transcription Factors/genetics , Transcription, Genetic/genetics , Transcriptional Activation/genetics , Base Sequence , Molecular Sequence Data , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
The expression of the acetyl xylan esterase II (axeII) gene from Penicillium purpurogenum is repressed by glucose and induced by xylan, as well as to a small degree by xylose and xylitol. This gene is expressed at neutral pH, but not under alkaline or acidic conditions, in agreement with previous findings for other xylanolytic genes of this organism. This is the first report showing pH regulation of an axe gene.
Subject(s)
Gene Expression Regulation, Bacterial , Penicillium , Base Sequence , Hydrogen-Ion Concentration , Molecular Sequence Data , Penicillium , Polymerase Chain Reaction , RNA, Fungal , Xylitol , XyloseABSTRACT
Penicillium purpurogenum produces several endoxylanases, two of which (XynA and XynB) have been purified and characterized. XynB has been sequenced, and it belongs to glycosyl hydrolase family 11. In this publication we report the structure of the xynA gene. The amino terminal sequence of the protein was determined and this allowed the design of oligonucleotides for use in polymerase chain reactions. Different polymerase chain reaction strategies were used to amplify and sequence the entire cDNA and the gene. The gene has an open reading frame of 1450 base pairs, including 8 introns with an average length of 56 base pairs each. Only one copy of this gene is present in the P. purpurogenum genome as shown by Southern blot. The gene encodes a protein of 329 residues (including the signal peptide), and the calculated molecular mass of the mature protein is 31,668 Da. Immunodetection assays of the expressed gene positively identified it as xynA, and sequence alignments indicate a high degree of similarity with family 10 endoxylanases. It is concluded that P. purpurogenum produces endoxylanases of family 10 and 11. The complementary action of endoxylanases of both families may be important for an efficient degradation of xylan by the fungus.