title: The F-box protein Grr1 regulates the stability of Ccn1, Cln3 and Hof1 and cell morphogenesis in Candida albicans.
abstract: Both G1 and mitotic cyclins have been implicated in regulating Candida albicans filamentous growth. We have investigated the functions of Grr1 whose orthologue in Saccharomyces cerevisiae is known to mediate ubiquitin-dependent degradation of the G1 cyclins Cln1 and Cln2. Here, we report that deleting C. albicans GRR1 causes significant stabilization of two G1 cyclins Ccn1 and Cln3 and pseudohyphal growth. grr1Delta cells are highly heterogeneous in length and many of them fail to separate after cytokinesis. Interestingly, some isolated rod-like G1 cells of similar sizes are present in the grr1Delta culture. Time-lapse microscopy revealed that the rod-shaped G1 cells first grew exclusively in width before budding and then the bud grew exclusively by apical extension until after cytokinesis, yielding rod-like daughter cells. Consistently, actin patches persistently localize to the bud tip until around the time of cytokinesis. Despite the pseudohyphal phenotype, grr1Delta cells respond normally to hyphal induction. Hyperphosphorylated Cln3 isoforms accumulate in grr1Delta cells, indicating that Grr1 selectively mediates their degradation in wild-type cells. grr1Delta pseudohyphal growth requires neither Hgc1 nor Swel, two important regulators of cell morphogenesis. Furthermore, the cellular level of Hof1, a protein having a role in cytokinesis, is also significantly increased in grr1Delta cells.
authors.affiliation: Institute of Life Sciences, Beijing Normal University, Beijing 100875, China.
authors.forename: Wan Jie
authors.initials: WJ
authors.lastname: Li
authors.forename: Yan Ming
authors.initials: YM
authors.lastname: Wang
authors.forename: Xin De
authors.initials: XD
authors.lastname: Zheng
authors.forename: Qing Mei
authors.initials: QM
authors.lastname: Shi
authors.forename: Ting Ting
authors.initials: TT
authors.lastname: Zhang
authors.forename: Chen
authors.initials: C
authors.lastname: Bai
authors.forename: Di
authors.initials: D
authors.lastname: Li
authors.forename: Jian Li
authors.initials: JL
authors.lastname: Sang
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000199:Actins / Q000378:metabolism; D002176:Candida albicans / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D016213:Cyclins / Q000235:genetics* / Q000378:metabolism; D044783:F-Box Proteins / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D018797:Cell Cycle Proteins; D016213:Cyclins; D044783:F-Box Proteins; D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins; C077337:CLN1 protein, Candida albicans; D005947:Glucose; D005690:Galactose