title: SEC14 is a specific requirement for secretion of phospholipase B1 and pathogenicity of Cryptococcus neoformans.
abstract: 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.
authors: Centre for Infectious Diseases and Microbiology, Sydney Medical School-Western, and Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead 2145 NSW, Australia.
authors: Methee
authors: M
authors: Chayakulkeeree
authors: Simon Andrew
authors: SA
authors: Johnston
authors: Johanes Bijosono
authors: JB
authors: Oei
authors: Sophie
authors: S
authors: Lev
authors: Peter Richard
authors: PR
authors: Williamson
authors: Christabel Frewen
authors: CF
authors: Wilson
authors: Xiaoming
authors: X
authors: Zuo
authors: Ana Lusia
authors: AL
authors: Leal
authors: Marilene Henning
authors: MH
authors: Vainstein
authors: Wieland
authors: W
authors: Meyer
authors: Tania Christine
authors: TC
authors: Sorrell
authors: Robin Charles
authors: RC
authors: May
authors: Julianne Teresa
authors: JT
authors: Djordjevic
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D003453:Cryptococcosis / Q000235:genetics / Q000378:metabolism; D003455:Cryptococcus neoformans / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D055786:Gene Knockout Techniques; D008245:Lysophospholipase / Q000378:metabolism*; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D049294:Phospholipid Transfer Proteins / Q000378:metabolism; D017384:Sequence Deletion
chemical_list: D002352:Carrier Proteins; D005656:Fungal Proteins; D049294:Phospholipid Transfer Proteins; D008245:Lysophospholipase