Svp1p defines a family of phosphatidylinositol 3,5-bisphosphate effectors.
Phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2), made by Fab1p, is essential for vesicle recycling from vacuole/lysosomal compartments and for protein sorting into multivesicular bodies. To isolate PtdIns(3,5)P2 effectors, we identified Saccharomyces cerevisiae mutants that display fab1delta-like vacuole enlargement, one of which lacked the SVP1/YFR021w/ATG18 gene. Expressed Svp1p displays PtdIns(3,5)P2 binding of exquisite specificity, GFP-Svp1p localises to the vacuole membrane in a Fab1p-dependent manner, and svp1delta cells fail to recycle a marker protein from the vacuole to the Golgi. Cells lacking Svp1p accumulate abnormally large amounts of PtdIns(3,5)P2. These observations identify Svp1p as a PtdIns(3,5)P2 effector required for PtdIns(3,5)P2-dependent membrane recycling from the vacuole. Other Svp1p-related proteins, including human and Drosophila homologues, bind PtdIns(3,5)P2 similarly. Svp1p and related proteins almost certainly fold as beta-propellers, and the PtdIns(3,5)P2-binding site is on the beta-propeller. It is likely that many of the Svp1p-related proteins that are ubiquitous throughout the eukaryotes are PtdIns(3,5)P2 effectors. Svp1p is not involved in the contributions of FAB1/PtdIns(3,5)P2 to MVB sorting or to vacuole acidification and so additional PtdIns(3,5)P2 effectors must exist.
Dove
Stephen K
SK
School of Biosciences, University of Birmingham, Birmingham, UK. s.k.dove@bham.ac.uk
Piper
Robert C
RC
McEwen
Robert K
RK
Yu
Jong W
JW
King
Megan C
MC
Hughes
David C
DC
Thuring
Jan
J
Holmes
Andrew B
AB
Cooke
Frank T
FT
Michell
Robert H
RH
Parker
Peter J
PJ
Lemmon
Mark A
MA
D000595:Amino Acid Sequence; D000071183:Autophagy-Related Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D011992:Endosomes / Q000378:metabolism*; D004926:Escherichia coli; D040461:Gene Components; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011485:Protein Binding; D017510:Protein Folding; D021381:Protein Transport / Q000502:physiology; D012229:Rhinovirus; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014617:Vacuoles / Q000378:metabolism*
C441008:ATG18 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D008565:Membrane Proteins; D018129:Phosphatidylinositol Phosphates; D029701:Saccharomyces cerevisiae Proteins; C106336:phosphatidylinositol 3,5-diphosphate; D049452:Green Fluorescent Proteins; C095504:FAB1 protein, S cerevisiae; D017853:Phosphotransferases (Alcohol Group Acceptor)