Role and mechanism of phosphatidylinositol-specific phospholipase C in survival and virulence of Cryptococcus neoformans.
Phospholipase B1 (Plb1) is secreted after release from its glycosylphosphatidylinositol anchor and is implicated in initiation and dissemination of infection of the pathogenic fungus, Cryptococcus neoformans. To investigate the role of phosphatidylinositol-specific phospholipase C (PI-PLC) in Plb1 secretion, we identified two putative PI-PLC-encoding genes in C. neoformans var. grubii (PLC1 and PLC2), and created Deltaplc1 and Deltaplc2 deletion mutants. In Deltaplc1, which expressed less PI-PLC activity than wild type (WT), three major cryptococcal virulence traits, Plb1 secretion, melanin production and growth at host temperature (37 degrees C) were abolished and absence of Plb1 secretion coincided with Plb1 accumulation in plasma membranes. In addition, Deltaplc1 cell walls were defective, as indicated by cell clumping and irregular morphology, slower growth and an inability to activate mitogen-activated protein kinase (MAPK) in the presence of cell wall-perturbing agents. In contrast to Deltaplc2, which was as virulent as WT, Deltaplc1 was avirulent in mice and exhibited attenuated killing of Caenorhabditis elegans at 25 degrees C, demonstrating that mechanism(s) independent of the 37 degrees C growth defect contribute to the virulence composite. We conclude that Plc1 is a central regulator of cryptococcal virulence, acting through the protein kinase C/MAPK pathway, that it regulates release of Plb1 from the plasma membrane and is a candidate antifungal drug target.
Centre for Infectious Diseases and Microbiology, ICPMR and Westmead Millennium Institute, University of Sydney at Westmead Hospital, NSW 2145, Australia.
Methee
M
Chayakulkeeree
Tania C
TC
Sorrell
A Rosemary
AR
Siafakas
Christabel F
CF
Wilson
Namfon
N
Pantarat
Kimberly J
KJ
Gerik
Ross
R
Boadle
Julianne T
JT
Djordjevic
D000818:Animals; D017173:Caenorhabditis elegans / Q000382:microbiology; D003453:Cryptococcosis / Q000382:microbiology; D003455:Cryptococcus neoformans / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity*; D004195:Disease Models, Animal; D025141:Drug Resistance, Fungal / Q000235:genetics; D004963:Estrenes / Q000494:pharmacology; D005656:Fungal Proteins / Q000378:metabolism; D017353:Gene Deletion; D018390:Gene Targeting; D005800:Genes, Fungal; D008543:Melanins / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D054801:Phosphoinositide Phospholipase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D021381:Protein Transport; D011760:Pyrrolidinones / Q000494:pharmacology; D014774:Virulence / Q000235:genetics
D004963:Estrenes; D005656:Fungal Proteins; D008543:Melanins; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D020929:Mitogen-Activated Protein Kinase Kinases; D054801:Phosphoinositide Phospholipase C