A steep phosphoinositide bis-phosphate gradient forms during fungal filamentous growth.
Membrane lipids have been implicated in many critical cellular processes, yet little is known about the role of asymmetric lipid distribution in cell morphogenesis. The phosphoinositide bis-phosphate PI(4,5)P(2) is essential for polarized growth in a range of organisms. Although an asymmetric distribution of this phospholipid has been observed in some cells, long-range gradients of PI(4,5)P(2) have not been observed. Here, we show that in the human pathogenic fungus Candida albicans a steep, long-range gradient of PI(4,5)P(2) occurs concomitant with emergence of the hyphal filament. Both sufficient PI(4)P synthesis and the actin cytoskeleton are necessary for this steep PI(4,5)P(2) gradient. In contrast, neither microtubules nor asymmetrically localized mRNAs are critical. Our results indicate that a gradient of PI(4,5)P(2), crucial for filamentous growth, is generated and maintained by the filament tip-localized PI(4)P-5-kinase Mss4 and clearing of this lipid at the back of the cell. Furthermore, we propose that slow membrane diffusion of PI(4,5)P(2) contributes to the maintenance of such a gradient.
Institute of Biology Valrose, Université Nice - Sophia Antipolis, 06108 Nice Cedex 2, France.
Aurélia
A
Vernay
Sébastien
S
Schaub
Isabelle
I
Guillas
Martine
M
Bassilana
Robert A
RA
Arkowitz
D019870:1-Phosphatidylinositol 4-Kinase / Q000096:biosynthesis / Q000235:genetics; D008841:Actin Cytoskeleton / Q000201:enzymology / Q000502:physiology*; D002176:Candida albicans / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity*; D016764:Cell Polarity / Q000502:physiology; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics; D025301:Hyphae / Q000201:enzymology / Q000254:growth & development*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000096:biosynthesis* / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000096:biosynthesis / Q000235:genetics
D005656:Fungal Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); D019870:1-Phosphatidylinositol 4-Kinase