title: Phosphatidylinositol 4,5-bisphosphate is required for invasive growth in Saccharomyces cerevisiae.
abstract: Phosphatidylinositol phosphates are important regulators of processes such as the cytoskeleton organization, membrane trafficking and gene transcription, which are all crucial for polarized cell growth. In particular, phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] has essential roles in polarized growth as well as in cellular responses to stress. In the yeast Saccharomyces cerevisiae, the sole phosphatidylinositol-4-phosphate 5-kinase (PI4P5K) Mss4p is essential for generating plasma membrane PtdIns(4,5)P2. Here, we show that Mss4p is required for yeast invasive growth in low-nutrient conditions. We isolated specific mss4 mutants that were defective in cell elongation, induction of the Flo11p flocculin, adhesion and cell wall integrity. We show that mss4-f12 cells have reduced plasma membrane PtdIns(4,5)P2 levels as well as a defect in its polarized distribution, yet Mss4-f12p is catalytically active in vitro. In addition, the Mss4-f12 protein was defective in localizing to the plasma membrane. Furthermore, addition of cAMP, but not an activated MAPKKK allele, partially restored the invasive growth defect of mss4-f12 cells. Taken together, our results indicate that plasma membrane PtdIns(4,5)P2 is crucial for yeast invasive growth and suggest that this phospholipid functions upstream of the cAMP-dependent protein kinase A signaling pathway.
authors.affiliation: Université Nice - Sophia Antipolis, Institute of Biology Valrose, 06108 Nice Cedex 2, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Guillas
authors.forename: Aurélia
authors.initials: A
authors.lastname: Vernay
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Vitagliano
authors.forename: Robert A
authors.initials: RA
authors.lastname: Arkowitz
mesh_terms: D002448:Cell Adhesion / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: C110690:FLO11 protein, S cerevisiae; D008562:Membrane Glycoproteins; D018129:Phosphatidylinositol Phosphates; D010743:Phospholipids; D029701:Saccharomyces cerevisiae Proteins; C106336:phosphatidylinositol 3,5-diphosphate
keywords: Invasive growth; PI4P5K; Phospholipids; Polarized growth; PtdIns(4,5)P2; Yeast