title: Dynamic, Rho1p-dependent localization of Pkc1p to sites of polarized growth.
abstract: In eukaryotes, the Rho GTPases and their effectors are key regulators of the actin cytoskeleton, membrane trafficking and secretion, cell growth, cell cycle progression and cytokinesis. Budding yeast Pkc1p, a protein kinase C-like enzyme involved in cell wall biosynthesis and cytoskeletal polarity, is structurally and functionally related to the Rho-associated kinases (PRK/ROCK) of mammalian cells. In this study, localization of Pkc1p was monitored in live cells using a GFP fusion (Pkc1p-GFP). Pkc1p-GFP showed dynamic spatial and temporal localization at sites of polarized growth. Early in the cell cycle, Pkc1p-GFP was found at the pre-bud site and bud tips, becoming delocalized as the cell progressed further and finally relocalizing around the mother-daughter bud neck in an incomplete ring, which persisted until cell separation. Bud localization was actin-dependent but stability of Pkc1p-GFP at the neck was actin-independent, although localization at both sites required functional Rho1p. In addition, Pkc1p-GFP showed rapid relocalization after cell wall damage. These results suggest that the roles of Pkc1p in both polarized growth and the response to cell wall stress are mediated by dynamic changes in its localization, and suggest an additional potential role in cytokinesis.
authors.affiliation: Department of Biochemistry, MSI/Wellcome Trust Biocentre, University of Dundee, Dow Street, Dundee DD1 5EH, UK. p.d.andrews@dundee.ac.uk.
authors.forename: P D
authors.initials: PD
authors.lastname: Andrews
authors.forename: M J
authors.initials: MJ
authors.lastname: Stark
mesh_terms: D000199:Actins / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002453:Cell Cycle / Q000502:physiology; D016764:Cell Polarity / Q000187:drug effects / Q000502:physiology*; D002473:Cell Wall / Q000187:drug effects / Q000201:enzymology; D005656:Fungal Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D007202:Indicators and Reagents / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics; D011493:Protein Kinase C; D011994:Recombinant Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines; D020741:rho GTP-Binding Proteins / Q000032:analysis / Q000378:metabolism*
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005656:Fungal Proteins; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D011994:Recombinant Proteins; D013844:Thiazoles; D053778:Thiazolidines; D049452:Green Fluorescent Proteins; C097993:Pkc1 protein, Trichoderma reesei; D011493:Protein Kinase C; D020741:rho GTP-Binding Proteins; C037067:latrunculin A