A novel function of Aft1 in regulating ferrioxamine B uptake: Aft1 modulates Arn3 ubiquitination in Saccharomyces cerevisiae

摘要

pAft1 is a transcriptional activator in iSaccharomyces cerevisiae/i that responds to iron availability and regulates the expression of genes in the iron regulon, such as iFET3/i, iFTR1/i and the iARN/i family. Using a two-hybrid screen, we found that Aft1 physically interacts with the FOB (ferrioxamine B) transporter Arn3. This interaction modulates the ability of Arn3 to take up FOB. The interaction between Arn3 and Aft1 was confirmed by β-galactosidase, co-immunoprecipitation and SPR (surface plasmon resonance) assays. Truncated Aft1 had a stronger interaction with Arn3 and caused a higher FOB-uptake activity than full-length Aft1. Interestingly, only full-length Aft1 induced the correct localization of Arn3 in response to FOB. Furthermore, we found Aft1 affected Arn3 ubiquitination. These results suggest that Aft1 interacts with Arn3 and may regulate the ubiquitination of Arn3 in the cytosolic compartment./p