title: Identification of ferrichrome- and ferrioxamine B-mediated iron uptake by Aspergillus fumigatus.
abstract: Aspergillus fumigatus is an opportunistic fungal pathogen for immunocompromised patients, and genes involved in siderophore metabolism have been identified as virulence factors. Recently, we identified the membrane transporters sit1 and sit2, which are putative virulence factors of A. fumigatus; sit1 and sit2 are homologous to yeast Sit1, and sit1 and sit2 gene expression was up-regulated after iron depletion. When expressed heterologously in Saccharomyces cerevisiae, sit1 and sit2 were localized to the plasma membrane; sit1 efficiently complemented ferrichrome (FC) and ferrioxamine B (FOB) uptake in yeast cells, whereas sit2 complemented only FC uptake. Deletion of sit1 resulted in a decrease in FOB and FC uptake, and deletion of sit2 resulted in a decrease in FC uptake in A. fumigatus It is of interest that a sit1 and sit2 double-deletion mutant resulted in a synergistic decrease in FC uptake activity. Both sit1 and sit2 were localized to the plasma membrane in A. fumigatus The expression levels of the sit1 and sit2 genes were dependent on hapX under low-but not high-iron conditions. Furthermore, mirB, and sidA gene expression was up-regulated and sreA expression down-regulated when sit1 and sit2 were deleted. Although sit1 and sit2 failed to affect mouse survival rate, these genes affected conidial killing activity. Taken together, our results suggest that sit1 and sit2 are siderophore transporters and putative virulence factors localized to the plasma membrane.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University Anam-dong, Sungbuk-gu, Seoul, Republic of Korea.
authors.forename: Yong-Sung
authors.initials: YS
authors.lastname: Park
authors.affiliation: School of Life Sciences and Biotechnology, Korea University Anam-dong, Sungbuk-gu, Seoul, Republic of Korea.
authors.forename: Ju-Yeon
authors.initials: JY
authors.lastname: Kim
authors.affiliation: School of Life Sciences and Biotechnology, Korea University Anam-dong, Sungbuk-gu, Seoul, Republic of Korea cheolwony@korea.ac.kr.
authors.forename: Cheol-Won
authors.initials: CW
authors.lastname: Yun
mesh_terms: D000818:Animals; D001232:Aspergillus fumigatus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D003676:Deferoxamine / Q000378:metabolism*; D005290:Ferric Compounds / Q000378:metabolism*; D005291:Ferrichrome / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D005290:Ferric Compounds; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D037521:Virulence Factors; D005291:Ferrichrome; C002577:ferrioxamine B; D007501:Iron; D003676:Deferoxamine
keywords: Aspergillus fumigatus; Saccharomyces cerevisiae; iron; siderophore; sit1; sit2