Copper alone, but not oxidative stress, induces copper-metallothionein gene in Neurospora crassa

Two metal response elements, flanking an antioxidant response element, were identified in regions upstream (-3730 bp) to copper metallothionein (CuMT) gene of Neurospora crassa. Presence of copper in culture media, but not of pro-oxidants like H2O2 or menadione, induced CuMT gene expression that could not be completely abolished by antioxidants such as N-acetyl cysteine and ascorbic acid. Get shift assays revealed the ability of nuclear extracts from copper induced cultures to bind PCR-amplified metal response or antioxidant response elements. Similar observations could not be made with Cultures exposed either to pro-oxidants or antioxidants. These results differentiate between CuMT gene induction by copper from antioxidant functions associated with the identified upstream elements. (C) 2004 Published by Elsevier B.V. on behalf of the Federation of European Microbiological Societies.