title: Identification and characterization of CPS1 as a hyaluronic acid synthase contributing to the pathogenesis of Cryptococcus neoformans infection.
abstract: Cryptococcus neoformans is a pathogenic yeast that often causes devastating meningoencephalitis in immunocompromised individuals. We have previously identified the C. neoformans CPS1 gene, which is required for a capsular layer on the outer cell wall. In this report, we investigate the function of the CPS1 gene and its pathogenesis. We demonstrated that treatment of yeast with either 4-methylumbelliferone or hyaluronidase resulted in a reduction of the level of C. neoformans binding to human brain microvascular endothelial cells (HBMEC). Yeast extracellular structures were also altered accordingly in hyaluronidase-treated cells. Furthermore, observation of yeast strains with different hyaluronic acid contents showed that the ability to bind to HBMEC is proportional to the hyaluronic acid content. A killing assay with Caenorhabditis elegans demonstrated that the CPS1 wild-type strain is more virulent than the cps1Delta strain. When CPS1 is expressed in Saccharomyces cerevisiae and Escherichia coli, hyaluronic acid can be detected in the cells. Additionally, we determined by fluorophore-assisted carbohydrate electrophoretic analysis that hyaluronic acid is a component of the C. neoformans capsule. The size of hyaluronic acid molecules is evaluated by gel filtration and transmission electron microscopy studies. Together, our results support that C. neoformans CPS1 encodes hyaluronic acid synthase and that its product, hyaluronic acid, plays a role as an adhesion molecule during the association of endothelial cells with yeast.
authors.affiliation: Division of Hematology-Oncology, Children's Hospital Los Angeles, Los Angeles, CA 90027, USA. ajong@chla.usc.edu
authors.forename: Ambrose
authors.initials: A
authors.lastname: Jong
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Wu
authors.forename: Han-Min
authors.initials: HM
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Luo
authors.forename: Kyung J
authors.initials: KJ
authors.lastname: Kwon-Chung
authors.forename: Yun C
authors.initials: YC
authors.lastname: Chang
authors.forename: Craig W
authors.initials: CW
authors.lastname: Lamunyon
authors.forename: Anna
authors.initials: A
authors.lastname: Plaas
authors.forename: Sheng-He
authors.initials: SH
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D017173:Caenorhabditis elegans / Q000382:microbiology; D003455:Cryptococcus neoformans / Q000201:enzymology* / Q000472:pathogenicity; D004925:Escherichia / Q000235:genetics; D019143:Evolution, Molecular; D014453:Glucuronosyltransferase / Q000737:chemistry* / Q000378:metabolism; D016695:Glycosyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D000076002:Hyaluronan Synthases; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014774:Virulence
chemical_list: D016695:Glycosyltransferases; C512598:CPS1 protein, Cryptococcus neoformans; D014453:Glucuronosyltransferase; D000076002:Hyaluronan Synthases