Loss of cell wall alpha(1-3) glucan affects Cryptococcus neoformans from ultrastructure to virulence.
Yeast cell walls are critical for maintaining cell integrity, particularly in the face of challenges such as growth in mammalian hosts. The pathogenic fungus Cryptococcus neoformans additionally anchors its polysaccharide capsule to the cell surface via alpha(1-3) glucan in the wall. Cryptococcal cells disrupted in their alpha glucan synthase gene were sensitive to stresses, including temperature, and showed difficulty dividing. These cells lacked surface capsule, although they continued to shed capsule material into the environment. Electron microscopy showed that the alpha glucan that is usually localized to the outer portion of the cell wall was absent, the outer region of the wall was highly disorganized, and the inner region was hypertrophic. Analysis of cell wall composition demonstrated complete loss of alpha glucan accompanied by a compensatory increase in chitin/chitosan and a redistribution of beta glucan between cell wall fractions. The mutants were unable to grow ina mouse model of infection, but caused death in nematodes. These studies integrate morphological and biochemical investigations of the role of alpha glucan in the cryptococcal cell wall.
Reese
Amy J
AJ
Department of Biological Sciences, Cedar Crest College, Allentown, PA 18104-6196, USA.
Yoneda
Aki
A
Breger
Julia A
JA
Beauvais
Anne
A
Liu
Hong
H
Griffith
Cara L
CL
Bose
Indrani
I
Kim
Myoung-Ju
MJ
Skau
Colleen
C
Yang
Sarah
S
Sefko
Julianne A
JA
Osumi
Masako
M
Latge
Jean-Paul
JP
Mylonakis
Eleftherios
E
Doering
Tamara L
TL
D000818:Animals; D017173:Caenorhabditis elegans / Q000382:microbiology; D002473:Cell Wall / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D002686:Chitin / Q000032:analysis; D048271:Chitosan / Q000032:analysis; D003455:Cryptococcus neoformans / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity* / Q000648:ultrastructure*; D004195:Disease Models, Animal; D017353:Gene Deletion; D005936:Glucans / Q000502:physiology*; D005964:Glucosyltransferases / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D016254:Mutagenesis, Insertional; D014774:Virulence / Q000235:genetics; D047071:beta-Glucans / Q000032:analysis
D005936:Glucans; D047071:beta-Glucans; D002686:Chitin; D048271:Chitosan; C045788:alpha-1,3-glucan; C036655:1,3-alpha-D-glucan synthase; D005964:Glucosyltransferases