A gene from Aspergillus nidulans with similarity to URE2 of Saccharomyces cerevisiae encodes a glutathione S-transferase which contributes to heavy metal and xenobiotic resistance.
Aspergillus nidulans is a saprophytic ascomycete that utilizes a wide variety of nitrogen sources. We identified a sequence from A. nidulans similar to the glutathione S-transferase-like nitrogen regulatory domain of Saccharomyces cerevisiae Ure2. Cloning and sequencing of the gene, designated gstA, revealed it to be more similar to URE2 than the S. cerevisiae glutathione S-transferases. However, creation and analysis of a gstA deletion mutant revealed that the gene does not participate in nitrogen metabolite repression. Instead, it encodes a functional theta class glutathione S-transferase that is involved in resistance to a variety of xenobiotics and metals and confers susceptibility to the systemic fungicide carboxin. Northern analysis showed that gstA transcription is strongly activated upon exposure to 1-chloro-2,4-dinitrobenzene and weakly activated by oxidative stress or growth on galactose as a carbon source. These results suggest that nitrogen metabolite repression in A. nidulans does not involve a homolog of the S. cerevisiae URE2 gene and that the global nitrogen regulatory system differs significantly in these two fungi.
Fraser
James A
JA
Department of Genetics, University of Melbourne, Victoria 3010, Australia.
Davis
Meryl A
MA
Hynes
Michael J
MJ
D001233:Aspergillus nidulans / Q000201:enzymology / Q000235:genetics*; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004352:Drug Resistance, Microbial / Q000235:genetics; D005656:Fungal Proteins; D015964:Gene Expression Regulation, Bacterial; D005979:Glutathione Peroxidase; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D019216:Metals, Heavy / Q000494:pharmacology; D009584:Nitrogen / Q000378:metabolism; D011328:Prions; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry; D017422:Sequence Analysis, DNA; D015262:Xenobiotics / Q000494:pharmacology
D001426:Bacterial Proteins; D002352:Carrier Proteins; D005656:Fungal Proteins; C105760:GstA protein, bacteria; D047908:Intracellular Signaling Peptides and Proteins; D019216:Metals, Heavy; D011328:Prions; D029701:Saccharomyces cerevisiae Proteins; D015262:Xenobiotics; D005979:Glutathione Peroxidase; C067020:URE2 protein, S cerevisiae; D005982:Glutathione Transferase; D009584:Nitrogen