title: CaSPA2 is important for polarity establishment and maintenance in Candida albicans.
abstract: Saccharomyces cerevisiae Spa2p is a component of polarisome that controls cell polarity. Here, we have characterized the role of its homologue, CaSpa2p, in the polarized growth in Candida albicans. During yeast growth, GFP-tagged CaSpa2p localized to distinct growth sites in a cell cycle-dependent manner, while during hyphal growth it persistently localized to hyphal tips throughout the cell cycle. Persistent tip localization of the protein was also observed in Catup1Delta and Canrg1Delta, mutants constitutive for filamentous growth. Caspa2Delta exhibited defects in polarity establishment and maintenance, such as random budding and failure to confine growth to a small surface area leading to round cells with wide, elongated bud necks and markedly thicker hyphae. It was also defective in nuclear positioning, presumably a result of defective interactions between cytoplasmic microtubules with certain polarity determinants. The highly conserved SHD-I and SHD-V domains were found to be important and responsible for different aspects of CaSpa2p function. Caspa2Delta exhibited no virulence in the mouse systemic candidiasis model. Because of the existence of distinct growth forms and the easy control of the switch between them in vitro, C. albicans may serve as a useful model in cell polarity research.
authors.affiliation: Microbial Collection and Screening Laboratory, Institute of Molecular and Cell Biology, Singapore 117609.
authors.forename: Xin-De
authors.initials: XD
authors.lastname: Zheng
authors.forename: Yan-Ming
authors.initials: YM
authors.lastname: Wang
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002176:Candida albicans / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity; D002177:Candidiasis / Q000382:microbiology; D002455:Cell Division / Q000235:genetics; D016764:Cell Polarity / Q000235:genetics*; D003598:Cytoskeletal Proteins; D004195:Disease Models, Animal; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017353:Gene Deletion; D005800:Genes, Fungal; D016681:Genome, Fungal; D025301:Hyphae / Q000254:growth & development / Q000378:metabolism; D051379:Mice; D008870:Microtubules / Q000648:ultrastructure; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017385:Sequence Homology; D014774:Virulence / Q000235:genetics
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins; C065889:SPA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins