Affiliation:
1. Aspergillus Unit
2. Public Health Research Institute, Newark, New Jersey
3. Histotechnology and Pathology Unit, Institut Pasteur, Paris, France
Abstract
ABSTRACT
α(1-3) glucan is a main component of the
Aspergillus fumigatus
cell wall. In spite of its importance, synthesis of this amorphous polymer has not been investigated to date. Two genes in
A. fumigatus
,
AGS1
and
AGS2
, are highly homologous to the
AGS
genes of
Schizosaccharomyces pombe
, which encode putative α(1-3) glucan synthases. The predicted Ags proteins of
A. fumigatus
have an estimated molecular mass of 270 kDa.
AGS1
and
AGS2
were disrupted in
A. fumigatus
. Both Δags mutants have similar altered hyphal morphologies and reduced conidiation levels. Only Δags1 presented a reduction in the α(1-3) glucan content of the cell wall. These results showed that Ags1p and Ags2p were functionally different. The cellular localization of the two proteins was in agreement with their different functions: Ags1p was localized at the periphery of the cell in connection with the cell wall, whereas Ags2p was intracellularly located. An original experimental model of invasive aspergillosis based on mixed infection and quantitative PCR was developed to analyze the virulence of
A. fumigatus
mutant and wild-type strains. Using this model, it was shown that the cell wall and morphogenesis defects of Δags1 and Δags2 were not associated with a reduction in virulence in either mutant. This result showed that a 50% reduction in the content of the cell wall α(1-3) glucan does not play a significant role in
A. fumigatus
pathogenicity.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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