SEC14 is a specific requirement for secretion of phospholipase B1 and pathogenicity of Cryptococcus neoformans

Authors

  • Methee Chayakulkeeree,

    1. Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia
    2. Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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  • Simon Andrew Johnston,

    1. School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT UK
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  • Johanes Bijosono Oei,

    1. Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia
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  • Sophie Lev,

    1. Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia
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  • Peter Richard Williamson,

    1. Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH Bethesda, MD, USA
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  • Christabel Frewen Wilson,

    1. Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia
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  • Xiaoming Zuo,

    1. Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia
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  • Ana Lusia Leal,

    1. Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia
    2. Centro de Biotecnologia-UFRGS Laboratório de Biologia de Fungos de Importância Médica e Biotecnológica Avenue. Bento Gonçalves, 9.500-Prédio 43.421-Lab.220 Bairro Agronomia CEP:91501-970 Porto Alegre/RS
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  • Marilene Henning Vainstein,

    1. Centro de Biotecnologia-UFRGS Laboratório de Biologia de Fungos de Importância Médica e Biotecnológica Avenue. Bento Gonçalves, 9.500-Prédio 43.421-Lab.220 Bairro Agronomia CEP:91501-970 Porto Alegre/RS
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  • Wieland Meyer,

    1. Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia
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  • Tania Christine Sorrell,

    1. Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia
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  • Robin Charles May,

    1. School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT UK
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  • Julianne Teresa Djordjevic

    Corresponding author
    1. Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia
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E-mail julie_djordjevic@wmi.usyd.edu.au; Tel. (+61) 2 9485 7046; Fax (+61) 2 9891 5317.

Summary

Secreted phospholipase B1 (CnPlb1) is essential for dissemination of Cryptococcus neoformans to the central nervous system (CNS) yet essential components of its secretion machinery remain to be elucidated. Using gene deletion analysis we demonstrate that CnPlb1 secretion is dependent on the CnSEC14 product, CnSec14-1p. CnSec14-1p is a homologue of the phosphatidylinositol transfer protein ScSec14p, which is essential for secretion and viability in Saccharomyces cerevisiae. In contrast to CnPlb1, neither laccase 1-induced melanization within the cell wall nor capsule induction were negatively impacted in CnSEC14-1 deletion mutants (CnΔsec14-1 and CnΔsec14-1CnΔsfh5). Similar to the CnPLB1 deletion mutant (CnΔplb1), CnΔsec14-1 was hypovirulent in mice and did not disseminate to the CNS by day 14 post infection. Furthermore, macrophage expulsion of live CnΔsec14-1 and CnΔplb1 (vomocytosis) was reduced. Individual deletion of CnSEC14-2, a closely related CnSEC14-1 homologue, and CnSFH5, a distantly related SEC fourteen like homologue, did not abrogate CnPlb1 secretion or virulence. However, reconstitution of CnΔsec14-1 with CnSEC14-1 or CnSEC14-2 restored both phenotypes, consistent with functional genetic redundancy. We conclude that CnPlb1 secretion is SEC14-dependent and that C. neoformans preferentially exports virulence determinants to the cell periphery via distinct pathways. We also demonstrate that CnPlb1 secretion is essential for vomocytosis.

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