Eukaryotic Cell doi:10.1128/EC.00309-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.
Candida albicans Als Adhesins Have Conserved Amyloid-Forming Sequences
Henry N. Otoo,
Kyeng Gea Lee,
Weigang Qiu,
and
Peter N. Lipke*
Department of Biology, Brooklyn College of City University of New York, New York, 11210; Department of Biology and Medical Laboratory Technology, Bronx Community College of City University of New York, Bronx, New York 10453; Department of Biology and the Center for Gene structure and Function, Hunter College of City University of New York, New York, 10021
* To whom correspondence should be addressed. Email:
plipke{at}brooklyn.cuny.edu.
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Abstract |
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The cell-wall bound Als adhesins of Candida albicans mediate both yeast-to-host tissue adherence and yeast aggregation. This aggregation is amyloid-like, with self-propagating secondary structure changes, amyloid-characteristic dye binding, and induced birefringence (Rauceo et al., 2004, Infect. Immun. 72:4948-4955). Therefore we determined whether Als proteins could form amyloid fibers with properties like those in cellular aggregation. The beta-aggregation predictor TANGO identified a heptapeptide sequence present in a highly conserved sequence with amyloid-forming potential in Als1p, Als3p, and Als5p. A tridecapeptide containing this sequence formed fibers that bound congo red and thioflavin T and had characteristic amyloid morphology. Als5p20-431 and Als5p20-664, large fragments of Als5p containing the amyloid sequence, also formed amyloid-like fibers and bound congo red under native conditions. Ka/Ks analysis showed that the amyloid-forming sequences are highly conserved in Als proteins, and evolve more slowly than other regions of the proteins. Therefore, amyloid forming ability itself is conserved in these proteins.
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