The distribution of phosphatidylinositol 4,5-bisphosphate in the budding yeast plasma membrane

• Published in: Histochemistry and cell biology Vol. 156; no. 2; pp. 109 - 121
• Main Authors: Kurokawa, Yuna, Konishi, Rikako, Tomioku, Kanna, Tanabe, Kenji, Fujita, Akikazu
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-08-2021; Springer Nature B.V
• Subjects: 1-Phosphatidylinositol 4-Kinase - metabolism; Biochemistry; Biomedical and Life Sciences; Biomedicine; Cell Biology; Cell Membrane - chemistry; Cell Membrane - metabolism; Developmental Biology; Electron microscopy; Golgi apparatus; Mutants; Original Paper; Phosphatidylinositol 4,5-diphosphate; Phosphatidylinositol 4,5-Diphosphate - analysis; Phosphatidylinositol 4,5-Diphosphate - metabolism; Phosphatidylinositol 4-phosphate; Phosphorylation; Plasma; Saccharomyces cerevisiae Proteins - metabolism; Saccharomycetales - chemistry; Saccharomycetales - metabolism; Yeast; Nanometer scale; Electron microscopy; Membrane domain; Lipid; Freeze-fracture; Plasma membrane
• ISSN: 0948-6143; 1432-119X
• DOI: 10.1007/s00418-021-01989-8

Phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P
2
) is generated through phosphorylation of phosphatidylinositol 4-phosphate (PtdIns(4)P) by Mss4p, the only PtdIns phosphate 5-kinase in yeast cells. PtdIns(4,5)P
2
is involved in various kinds of yeast functions. PtdIns(4)P is not only the immediate precursor of PtdIns(4,5)P
2
, but also an essential signaling molecule in the plasma membrane, Golgi, and endosomal system. To analyze the distribution of PtdIns(4,5)P
2
and PtdIns(4)P in the yeast plasma membrane at a nanoscale level, we employed a freeze–fracture electron microscopy (EM) method that physically immobilizes lipid molecules in situ. It has been reported that the plasma membrane of budding yeast can be divided into three distinct areas: furrowed, hexagonal, and undifferentiated flat. Previously, using the freeze–fracture EM method, we determined that PtdIns(4)P is localized in the undifferentiated flat area, avoiding the furrowed and hexagonal areas of the plasma membrane. In the present study, we found that PtdIns(4,5)P
2
was localized in the cytoplasmic leaflet of the plasma membrane, and concentrated in the furrowed area. There are three types of PtdIns 4-kinases which are encoded by
stt4
,
pik1
, and
lsb6
. The labeling density of PtdIns(4)P in the plasma membrane significantly decreased in both
pik1
ts
and
stt4
ts
mutants. However, the labeling densities of PtdIns(4,5)P
2
in the plasma membrane of both the
pik1
ts
and
stt4
ts
mutants were comparable to that of the wild type yeast. These results suggest that PtdIns(4)P produced by either Pik1p or Stt4p is immediately phosphorylated by Mss4p and converted to PtdIns(4,5)P
2
at the plasma membrane.