title: UME6 is a crucial downstream target of other transcriptional regulators of true hyphal development in Candida albicans.
abstract: True hyphal growth of Candida albicans can be induced by several environmental conditions and contributes significantly to the high virulence of this pathogenic fungus. The transcriptional network that governs hyphal morphogenesis is complex, depends on several regulators and is not completely understood. Recently, CaUME6, a homolog of the Saccharomyces cerevisiae UME6 gene, has been shown to be required for hyphal elongation. In the present study, the C. albicans ume6Delta strain showed a complete defect in hyphae formation under all the growth conditions tested. UME6 was repressed by the Nrg1-Tup1 repressor in yeast-form cells but NRG1 was not repressed by Ume6p under hyphal growth conditions. Wild-type UME6 expression depended on each hyphal regulator tested, and ectopic UME6 expression in efg1Delta, cph1Delta and ras1Delta cells rescued the hyphal defects of these mutants under some hyphal growth conditions. Thus, UME6 is a common downstream target of regulators promoting hyphal development. Ectopic UME6 expression promoted both germ tube formation and hyphal elongation. The expression of all hyphae-specific genes investigated depended on UME6 expression. A model for transcriptional regulation of hyphal development and the role of Ume6p is proposed.
authors.affiliation: Department of Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, Salzburg, Austria.
authors.forename: Ute
authors.initials: U
authors.lastname: Zeidler
authors.forename: Thomas
authors.initials: T
authors.lastname: Lettner
authors.forename: Caroline
authors.initials: C
authors.lastname: Lassnig
authors.forename: Mathias
authors.initials: M
authors.lastname: Müller
authors.forename: Robert
authors.initials: R
authors.lastname: Lajko
authors.forename: Helmut
authors.initials: H
authors.lastname: Hintner
authors.forename: Michael
authors.initials: M
authors.lastname: Breitenbach
authors.forename: Arnold
authors.initials: A
authors.lastname: Bito
mesh_terms: D002176:Candida albicans / Q000235:genetics / Q000502:physiology*; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D025301:Hyphae / Q000235:genetics / Q000254:growth & development*; D008954:Models, Biological; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D012097:Repressor Proteins