title: Leu1 plays a role in iron metabolism and is required for virulence in Cryptococcus neoformans.
abstract: Amino acid biosynthetic pathways that are absent in mammals are considered an attractive target for antifungal therapy. Leucine biosynthesis is one such target pathway, consisting of a five-step conversion process starting from the valine precursor 2-keto-isovalerate. Isopropylmalate dehydrogenase (Leu1) is an Fe-S cluster protein that is required for leucine biosynthesis in the model fungus Saccharomyces cerevisiae. The human pathogenic fungus Cryptococcus neoformans possesses an ortholog of S. cerevisiae Leu1, and our previous transcriptome data showed that the expression of LEU1 is regulated by iron availability. In this study, we characterized the role of Leu1 in iron homeostasis and the virulence of C. neoformans. We found that deletion of LEU1 caused leucine auxotrophy and that Leu1 may play a role in the mitochondrial-cytoplasmic Fe-S cluster balance. Whereas cytoplasmic Fe-S protein levels were not affected, mitochondrial Fe-S proteins were up-regulated in the leu1 mutant, suggesting that Leu1 mainly influences mitochondrial iron metabolism. The leu1 mutant also displayed increased sensitivity to oxidative stress and cell wall/membrane disrupting agents, which may have been caused by mitochondrial dysfunction. Furthermore, the leu1 mutant was deficient in capsule formation and showed attenuated virulence in a mouse inhalation model of cryptococcosis. Overall, our results indicate that Leu1 plays a role in iron metabolism and is required for virulence in C. neoformans.
authors.affiliation: Department of Systems Biotechnology, Chung-Ang University, Anseong 456-756, Republic of Korea.
authors.forename: Eunsoo
authors.initials: E
authors.lastname: Do
authors.affiliation: The Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Guanggan
authors.initials: G
authors.lastname: Hu
authors.affiliation: The Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Mélissa
authors.initials: M
authors.lastname: Caza
authors.affiliation: The Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Debora
authors.initials: D
authors.lastname: Oliveira
authors.affiliation: The Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: James W
authors.initials: JW
authors.lastname: Kronstad
authors.affiliation: Department of Systems Biotechnology, Chung-Ang University, Anseong 456-756, Republic of Korea. Electronic address: whjung@cau.ac.kr.
authors.forename: Won Hee
authors.initials: WH
authors.lastname: Jung
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D003453:Cryptococcosis / Q000382:microbiology; D003455:Cryptococcus neoformans / Q000235:genetics* / Q000472:pathogenicity* / Q000648:ultrastructure; D004195:Disease Models, Animal; D062607:Fungal Capsules / Q000502:physiology; D005656:Fungal Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D006706:Homeostasis; D006836:Hydro-Lyases / Q000235:genetics*; D007501:Iron / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D007930:Leucine / Q000096:biosynthesis*; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D007506:Iron-Sulfur Proteins; D007501:Iron; D006836:Hydro-Lyases; C021455:3-isopropylmalate dehydratase; D007930:Leucine
keywords: C. neoformans; Fe–S cluster; Leu1; Mitochondria; Virulence