Septins function in Candida albicans hyphal growth.
Amy Warenda, Stephen Martin, James Konopka
Microbiology, State University of New York, Life Sciences Bldg., Stony
Brook, NY 11794-5222, United States
The ability of Candida albicans to form hyphae is strongly
associated with its virulence. We therefore initiated studies to
determine the role of septins in C. albicans morphogenesis.
Septins comprise a class of filament-forming proteins that were
previously found to be involved in morphogenesis and cytokinesis of
S. cerevisiae. We identified homologues to the seven known
septins in S. cerevisiae as open reading frames in the C.
albicans genome. A septin fusion protein (Cdc10-GFP) localized as a
tight ring at the mother-bud junction during budding growth, and was
also detected at septation sites of hyphae. Interestingly, the septins
also localized as a broad, diffuse band at the base of hyphae during
early phases of germ tube emergence, suggesting that they are
differentially regulated in budding versus hyphal growth. Gene deletion
studies showed that two of the seven septin genes (CDC3 and CDC12)
appear to be essential for viability. Deletion of two other septins
(CDC10 and CDC11) results in elongated buds and a multibudded phenotype.
The hyphae formed by these mutants display a higher degree of curvature,
altered distribution of chitin, and aberrant site selection for
formation of a second hypha. We are currently analyzing individual
septin-binding proteins to ascertain their role in septin regulation and
budding and hyphal morphogenesis. These results demonstrate a role for
septins in hyphal growth that is distinct from their role in
cytokinesis.
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