Dissertation/Thesis Abstract

Characterization of four septin genes, and detection of genetic interactions between WdCDC10 and chitin synthase genes during yeast budding in the polymorphic mold, Wangiella ( Exophiala) dermatitidis
by Park, Changwon, Ph.D., The University of Texas at Austin, 2007, 162; 3684368
Abstract (Summary)

Septins are a highly conserved family of eukaryotic proteins having significant homology within and among species. In the budding yeast, Saccharomyces cerevisiae, a septin-based hierarchy of proteins is required to localize chitin in the bud neck prior to septum formation. However, this process has not been clarified in a filamentous, conidiogenous fungus capable of yeast growth, such as Wangiella dermatitidis, a polymorphic agent of human phaeohyphomycosis. Prior studies of this melanized mold showed that some chitin synthase mutants (wdchsΔ) have defects in yeast septum formation, suggesting that the septins of W. dermatitidis might functionally associate with some of its chitin synthases (WdChsp). To test this hypothesis, four vegetative septin homologs of S. cerevisiae were cloned from W. dermatitidis and designated WdCDC3, WdCDC10, WdCDC11, and WdCDC12. Of the four, only WdCDC3 functionally complemented completely a strain of S. cerevisiae with a ts mutation in the corresponding gene, although WdCDC12 did so partially. Functional characterizations by mutagenesis of the four W. dermatitidis septin genes revealed that resulting mutants (wdcdΔ) each had unique defects in yeast growth and morphology, indicating that each septin carried out a distinct function. Furthermore, when a wdcdc10Δ mutation was introduced into five different wdchsΔ strains, weak genetic interactions were detected between WdCDC10 and WdCHS3 and WdCHS4, and a strong interaction between WdCDC10 and WdCHS5. Cytological studies showed that WdChs5p was mislocalized in some septin mutants, including wdcdc10 Δ. These results confirmed that in W. dermatitidis septins are important for proper cellular morphogenesis, cytokinesis, and especially septum formation through associations with some chitin synthases.

Indexing (document details)
Advisor: Szaniszlo, Paul Joseph
Commitee:
School: The University of Texas at Austin
Department: Microbiology, Molecular Biology and Biochemistry
School Location: United States -- Texas
Source: DAI-B 76/07(E), Dissertation Abstracts International
Source Type: DISSERTATION
Subjects: Genetics, Cellular biology, Microbiology
Keywords: Chitin synthase, Polymorphic mold, Septin genes
Publication Number: 3684368
ISBN: 9781321594058
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