Defects in phosphate acquisition and storage influence virulence of Cryptococcus neoformans.
Nutrient acquisition and sensing are critical aspects of microbial pathogenesis. Previous transcriptional profiling indicated that the fungal pathogen Cryptococcus neoformans, which causes meningoencephalitis in immunocompromised individuals, encounters phosphate limitation during proliferation in phagocytic cells. We therefore tested the hypothesis that phosphate acquisition and polyphosphate metabolism are important for cryptococcal virulence. Deletion of the high-affinity uptake system interfered with growth on low-phosphate medium, perturbed the formation of virulence factors (capsule and melanin), reduced survival in macrophages, and attenuated virulence in a mouse model of cryptococcosis. Additionally, analysis of nutrient sensing functions for C. neoformans revealed regulatory connections between phosphate acquisition and storage and the iron regulator Cir1, cyclic AMP (cAMP)-dependent protein kinase A (PKA), and the calcium-calmodulin-activated protein phosphatase calcineurin. Deletion of the VTC4 gene encoding a polyphosphate polymerase blocked the ability of C. neoformans to produce polyphosphate. The vtc4 mutant behaved like the wild-type strain in interactions with macrophages and in the mouse infection model. However, the fungal load in the lungs was significantly increased in mice infected with vtc4 deletion mutants. In addition, the mutant was impaired in the ability to trigger blood coagulation in vitro, a trait associated with polyphosphate. Overall, this study reveals that phosphate uptake in C. neoformans is critical for virulence and that its regulation is integrated with key signaling pathways for nutrient sensing.
Michael Smith Laboratories, Department of Microbiology and Immunology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada.
Matthias
M
Kretschmer
Michael Smith Laboratories, Department of Microbiology and Immunology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada.
Ethan
E
Reiner
Michael Smith Laboratories, Department of Microbiology and Immunology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada.
Guanggan
G
Hu
Michael Smith Laboratories, Department of Microbiology and Immunology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada.
Nicola
N
Tam
Michael Smith Laboratories, Department of Microbiology and Immunology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada.
Debora L
DL
Oliveira
Michael Smith Laboratories, Department of Microbiology and Immunology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada.
Melissa
M
Caza
Michael Smith Laboratories, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
Ju Hun
JH
Yeon
Department of Systems Biotechnology, Chung-Ang University, Anseong-Si, Gyeonggi-Do, Republic of Korea.
Jeongmi
J
Kim
Michael Smith Laboratories, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
Christian J
CJ
Kastrup
Department of Systems Biotechnology, Chung-Ang University, Anseong-Si, Gyeonggi-Do, Republic of Korea.
Won Hee
WH
Jung
Michael Smith Laboratories, Department of Microbiology and Immunology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada kronstad@msl.ubc.ca.
James W
JW
Kronstad
D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D003453:Cryptococcosis / Q000382:microbiology*; D003455:Cryptococcus neoformans / Q000472:pathogenicity* / Q000502:physiology*; D016572:Cyclosporine / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D010710:Phosphates / Q000378:metabolism*; D011122:Polyphosphates / Q000378:metabolism; D014774:Virulence; D015032:Zinc / Q000494:pharmacology
D005656:Fungal Proteins; D010710:Phosphates; D011122:Polyphosphates; D016572:Cyclosporine; D015032:Zinc