Identification of high-affinity copper transporters in Aspergillus fumigatus

Abstract

We investigated the copper metabolism of Aspergillus fumigatus, which has not been characterized well. We cloned the putative copper transporters ctrA(2) and ctrC from A. fumigatus and investigated the functions of these transporters in copper metabolism. Four putative copper transporters were identified in the A. fumigatus genome; ctrA(2) and ctrC complemented CTR1 functionally and localized to the plasma membrane in Saccharomyces cerevisiae. ctrA(2) and ctrC single-deletion mutants and a double-deletion mutant of ctrA(2) and ctrC were constructed in A. fumigatus. The ctrA(2) and ctrC double-deletion mutant exhibited a growth defect on Aspergillus minimal medium (AMM) supplemented with bathocuproine disulfonic acid (BCS) and was sensitive to H2O2. Furthermore, the deletion of ctrA(2) and ctrC reduced superoxide dismutase (SOD) activity, laccase activity, and intracellular copper contents. The activities of the ctrA(2) and ctrC genes were up-regulated by BCS treatment. In addition, the deletion of ctrA(2) up-regulated ctrC and vice versa. ctrA(2) and ctrC were localized to the A. fumigatus plasma membrane. Although ctrA(2) and ctrC failed to affect the mouse survival rate, these genes affected conidial killing activity. Taken together, these results indicate that ctrA(2) and ctrC may function as membrane transporters and that the involvement of these genes in pathogenicity merits further investigation. (C) 2014 Elsevier Inc. All rights reserved.