title: Identification and Characterization of a Novel Aspergillus fumigatus Rhomboid Family Putative Protease, RbdA, Involved in Hypoxia Sensing and Virulence.
abstract: Aspergillus fumigatus is the most common pathogenic mold infecting humans and a significant cause of morbidity and mortality in immunocompromised patients. In invasive pulmonary aspergillosis, A. fumigatus spores are inhaled into the lungs, undergoing germination and invasive hyphal growth. The fungus occludes and disrupts the blood vessels, leading to hypoxia and eventual tissue necrosis. The ability of this mold to adapt to hypoxia is regulated in part by the sterol regulatory element binding protein (SREBP) SrbA and the DscA to DscD Golgi E3 ligase complex critical for SREBP activation by proteolytic cleavage. Loss of the genes encoding these proteins results in avirulence. To identify novel regulators of hypoxia sensing, we screened the Neurospora crassa gene deletion library under hypoxia and identified a novel rhomboid family protease essential for hypoxic growth. Deletion of the A. fumigatus rhomboid homolog rbdA resulted in an inability to grow under hypoxia, hypersensitivity to CoCl2, nikkomycin Z, fluconazole, and ferrozine, abnormal swollen tip morphology, and transcriptional dysregulation-accurately phenocopying deletion of srbA. In vivo, rbdA deletion resulted in increased sensitivity to phagocytic killing, a reduced inflammatory Th1 and Th17 response, and strongly attenuated virulence. Phenotypic rescue of the ΔrbdA mutant was achieved by expression and nuclear localization of the N terminus of SrbA, including its HLH domain, further indicating that RbdA and SrbA act in the same signaling pathway. In summary, we have identified RbdA, a novel putative rhomboid family protease in A. fumigatus that mediates hypoxia adaptation and fungal virulence and that is likely linked to SrbA cleavage and activation.
authors.affiliation: Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Yakir
authors.initials: Y
authors.lastname: Vaknin
authors.affiliation: Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), Jena, Germany.|Friedrich Schiller University, Institute of Microbiology, Jena, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Hillmann
authors.affiliation: Department of Experimental Medicine, Università degli Studi di Perugia, Perugia, Italy.
authors.forename: Rossana
authors.initials: R
authors.lastname: Iannitti
authors.affiliation: Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Netali
authors.initials: N
authors.lastname: Ben Baruch
authors.affiliation: Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Hana
authors.initials: H
authors.lastname: Sandovsky-Losica
authors.affiliation: Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Yona
authors.initials: Y
authors.lastname: Shadkchan
authors.affiliation: Department of Experimental Medicine, Università degli Studi di Perugia, Perugia, Italy.
authors.forename: Luigina
authors.initials: L
authors.lastname: Romani
authors.affiliation: Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), Jena, Germany.|Friedrich Schiller University, Institute of Microbiology, Jena, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Brakhage
authors.affiliation: Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), Jena, Germany.|Friedrich Schiller University, Institute of Microbiology, Jena, Germany.
authors.forename: Olaf
authors.identifier: http://orcid.org/0000-0002-9493-6402
authors.initials: O
authors.lastname: Kniemeyer
authors.affiliation: Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel nosherov@post.tau.ac.il.
authors.forename: Nir
authors.initials: N
authors.lastname: Osherov
mesh_terms: D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D001228:Aspergillosis / Q000235:genetics / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D001232:Aspergillus fumigatus / Q000187:drug effects / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D003035:Cobalt / Q000494:pharmacology; D004195:Disease Models, Animal; D005260:Female; D005656:Fungal Proteins / Q000235:genetics* / Q000276:immunology; D015966:Gene Expression Regulation, Fungal; D054884:Host-Pathogen Interactions; D000860:Hypoxia / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D016867:Immunocompromised Host; D007814:Larva / Q000276:immunology / Q000382:microbiology; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D009036:Moths / Q000276:immunology / Q000382:microbiology; D009154:Mutation; D009492:Neurospora crassa / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity; D010447:Peptide Hydrolases / Q000235:genetics* / Q000276:immunology; D015398:Signal Transduction; D013172:Spores, Fungal / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity; D051779:Sterol Regulatory Element Binding Proteins / Q000235:genetics / Q000276:immunology; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000276:immunology; D014774:Virulence
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; D051779:Sterol Regulatory Element Binding Proteins; D003035:Cobalt; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases; C018021:cobaltous chloride