title: Secretion and filamentation are mediated by the Candida albicans t-SNAREs Sso2p and Sec9p.
abstract: To study the role of late secretion in Candida albicans pathogenesis, we created conditional mutant C. albicans strains in which the t-SNARE-encoding genes SSO2 or SEC9 were placed under the control of a tetracycline-regulated promoter. In repressing conditions, C. albicans tetR-SSO2 and tetR-SEC9 mutant strains were defective in cytokinesis and secretion of aspartyl proteases and lipases. The mutant strains also exhibited a defect in filamentation compared with controls, and thus, we followed the fate of the C. albicans Spitzenkörper, an assembly of secretory vesicles thought to act as a vesicle supply center for the growing hyphae. In the absence of Ca Sso2p, the Spitzenkörper dissipated within 5 h and thin-section electron microscopy revealed an accumulation of secretory vesicles. Moreover, the hyphal tip developed into a globular yeast-like structure rather than maintaining a typical narrow hyphae. These studies indicate that late secretory t-SNARE proteins in C. albicans are required for fundamental cellular processes and contribute to virulence-related attributes of C. albicans pathogenesis. Moreover, these results provide direct evidence for a key role of SNARE proteins in vesicle-mediated polarized hyphal growth of C. albicans.
authors.affiliation: Section of Infectious Diseases, New Mexico Veterans Healthcare System, Albuquerque, NM, USA; University of New Mexico Health Science Center, Albuquerque, NM, USA.
authors.forename: Stella M
authors.initials: SM
authors.lastname: Bernardo
authors.forename: Hallie S
authors.initials: HS
authors.lastname: Rane
authors.forename: Alba
authors.initials: A
authors.lastname: Chavez-Dozal
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Lee
mesh_terms: D002176:Candida albicans / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D048749:Cytokinesis; D004798:Enzymes / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D025301:Hyphae / Q000235:genetics*; D008854:Microscopy, Electron; D050600:SNARE Proteins / Q000378:metabolism*
chemical_list: D004798:Enzymes; D005656:Fungal Proteins; D050600:SNARE Proteins
keywords: SNARE; Spitzenkörper; aspartyl protease; hyphae; lipase