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Journal of Bacteriology, September 1999, p. 5636-5643, Vol. 181, No. 18
Laboratory of Clinical Investigation,
National Institute of Allergy and Infectious Diseases, National
Institutes of Health, Bethesda, Maryland 20892
Received 29 April 1999/Accepted 14 June 1999
Cryptococcus neoformans is a pathogenic fungus which
most commonly affects the central nervous system and causes fatal
meningoencephalitis primarily in patients with AIDS. This fungus
produces a thick extracellular polysaccharide capsule which is well
recognized as a virulence factor. Here, we describe the isolation and
characterization of a novel gene, CAP10, which is required
for capsule formation. Complementation of the acapsular
cap10 mutant produced an encapsulated strain and the
deletion of CAP10 from a wild strain resulted in an
acapsular phenotype. The molecular mass of the hemagglutinin epitope-tagged Cap10p is about 73 kDa, which is similar to the size
predicted from sequence analysis. When CAP10 was fused with a hybrid green fluorescent protein construct, the fluorescence signals
appeared as patches in the cytoplasm. Using a reporter gene construct,
we found that CAP10 was expressed at high levels in
late-stationary-phase cells. In addition, we found that the expression
levels of CAP10 are modulated by the transcriptional factor
STE12
0021-9193/99/$04.00+0
Isolation, Characterization, and Localization of a
Capsule-Associated Gene, CAP10, of Cryptococcus
neoformans
. Deletion of STE12
downregulated
the expression levels of CAP10 while overexpression of
STE12
upregulated the expression levels of
CAP10. Animal model studies indicate that deletion of the
CAP10 gene results in the loss of virulence, and complementation of the acapsular phenotype of cap10
restores virulence. Thus, CAP10 is required for capsule
formation and virulence.
*
Corresponding author. Mailing address: Building 10, Room 11C304, National Institutes of Health, Bethesda, MD 20892. Phone: (301) 496-1602. Fax: (301) 402-1003. E-mail:
June_Kwon-chung{at}nih.gov.
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