ctr2 links copper homeostasis to polysaccharide capsule formation and phagocytosis inhibition in the human fungal pathogen cryptococcus neoformansctr2链接铜稳态多糖胶囊形成和吞噬作用抑制人类真菌病原体新型隐球菌.pdf

Ctr2 Links Copper Homeostasis to Polysaccharide Capsule Formation and Phagocytosis Inhibition in the Human Fungal Pathogen Cryptococcus neoformans Cheryl D. Chun, Hiten D. Madhani* Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America Abstract Cryptococcus neoformans is a human opportunistic fungal pathogen responsible for ,1/3 of HIV/AIDS deaths worldwide. This budding yeast expresses a polysaccharide capsule necessary for virulence. Capsule production inhibits phagocytosis by macrophages. Here we describe results that link copper homeostasis to capsule production and the inhibition of phagocytosis. Specifically, using Agrobacterium-mediated insertional mutagenesis, we identified an insertion in the promoter region of the putative copper transporter-encoding gene CTR2 that results in reduced expression of CTR2 and increased phagocytosis by murine RAW264.7 macrophages. The mutant also displayed sensitivity to copper starvation and defects in polysaccharide capsule production and melanization. These defects were all reversed by genetic correction of the promoter insertion by homologous targeting. Several melanization-defective mutants identified previously, those in the RIM20, RIM101, and VPS25 genes, also display sensitivity to copper starvation, reduced capsule production and increased phagocytosis. Together these results indicate a previously undescribed link between copper homeostasis to polysaccharide capsule production and phagocytosis inhibition in Cryptococcus neoformans. Citation: Chun CD, Madhani HD (2010) Ctr2 Links Copper Homeostasis to Polysaccharide Capsule Formation and Phagocytosis Inhibition in the Human Fungal Pathogen Cryptococcus neoformans. PLoS ONE 5(9): e12503. doi:10.1371/journal.pone.0012503