Atg18 regulates organelle morphology and Fab1 kinase activity independent of its membrane recruitment by phosphatidylinositol 3,5-bisphosphate.
The lipid kinase Fab1 governs yeast vacuole homeostasis by generating PtdIns(3,5)P(2) on the vacuolar membrane. Recruitment of effector proteins by the phospholipid ensures precise regulation of vacuole morphology and function. Cells lacking the effector Atg18p have enlarged vacuoles and high PtdIns(3,5)P(2) levels. Although Atg18 colocalizes with Fab1p, it likely does not directly interact with Fab1p, as deletion of either kinase activator-VAC7 or VAC14-is epistatic to atg18Delta: atg18Deltavac7Delta cells have no detectable PtdIns(3,5)P(2). Moreover, a 2xAtg18 (tandem fusion) construct localizes to the vacuole membrane in the absence of PtdIns(3,5)P(2), but requires Vac7p for recruitment. Like the endosomal PtdIns(3)P effector EEA1, Atg18 membrane binding may require a protein component. When the lipid requirement is bypassed by fusing Atg18 to ALP, a vacuolar transmembrane protein, vac14Delta vacuoles regain normal morphology. Rescue is independent of PtdIns(3,5)P(2), as mutation of the phospholipid-binding site in Atg18 does not prevent vacuole fission and properly regulates Fab1p activity. Finally, the vacuole-specific type-V myosin adapter Vac17p interacts with Atg18p, perhaps mediating cytoskeletal attachment during retrograde transport. Atg18p is likely a PtdIns(3,5)P(2)"sensor," acting as an effector to remodel membranes as well as regulating its synthesis via feedback that might involve Vac7p.
Efe
Jem A
JA
Department of Cellular and Molecular Medicine, Cornell Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA.
Botelho
Roberto J
RJ
Emr
Scott D
SD
D000071183:Autophagy-Related Proteins; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004789:Enzyme Activation; D005420:Flavoproteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D017930:Genes, Reporter / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D015388:Organelles / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism
C441008:ATG18 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D005420:Flavoproteins; D008565:Membrane Proteins; D018129:Phosphatidylinositol Phosphates; D029701:Saccharomyces cerevisiae Proteins; C452435:VAC14 protein, S cerevisiae; C106336:phosphatidylinositol 3,5-diphosphate; C095504:FAB1 protein, S cerevisiae; D017853:Phosphotransferases (Alcohol Group Acceptor); C110669:FIG4 protein, S cerevisiae; D010744:Phosphoric Monoester Hydrolases
J Biol Chem. 2000 Feb 4;275(5):3699-705
10652369
Nature. 1997 Nov 13;390(6656):187-92
9367158
EMBO J. 2000 Sep 1;19(17):4577-88
10970851
Yeast. 2001 Sep 15;18(12):1155-71
11536337
Traffic. 2003 Apr;4(4):201-13
12694559
Dev Cell. 2003 Sep;5(3):499-511
12967568
J Biol Chem. 2003 Oct 3;278(40):38786-95
12878588
Annu Rev Genet. 2003;37:435-60
14616069
Mol Biol Cell. 2004 Jan;15(1):24-36
14528018
Dev Cell. 2004 Jan;6(1):79-90
14723849
EMBO J. 2004 May 5;23(9):1922-33
15103325
Mol Biol Cell. 2004 Jun;15(6):2652-63
15020712
Mol Cell Biol. 1997 Dec;17(12):6847-58
9372916
Microbiol Mol Biol Rev. 1998 Mar;62(1):230-47
9529893
Nature. 1998 Jul 30;394(6692):494-8
9697774
Mol Cell. 1998 Jul;2(1):157-62
9702203
Yeast. 1998 Jul;14(10):953-61
9717241
J Cell Biol. 1998 Oct 5;143(1):65-79
9763421
Curr Biol. 1998 Nov 5;8(22):1219-22
9811604
J Biol Chem. 1999 Jul 30;274(31):21589-97
10419465
Eukaryot Cell. 2005 Feb;4(2):281-8
15701790
J Cell Sci. 2005 May 15;118(Pt 10):2093-104
15890985
Curr Opin Cell Biol. 2005 Aug;17(4):402-8
15975782
Traffic. 2005 Dec;6(12):1070-7
16262719
Nature. 2005 Dec 1;438(7068):597-604
16319879
J Biol Chem. 2005 Dec 23;280(51):41785-8
16230342
J Cell Biol. 2006 Feb 27;172(5):693-704
16492811
Eukaryot Cell. 2006 Apr;5(4):723-31
16607019
IUBMB Life. 2006 May-Jun;58(5-6):296-303
16754321
Autophagy. 2005 Jul;1(2):101-9
16874040
FEBS Lett. 2006 Aug 21;580(19):4632-8
16876790
Nature. 2006 Oct 12;443(7112):651-7
17035995
FEBS Lett. 2001 Nov 9;508(1):23-8
11707261
Mol Biol Cell. 2001 Dec;12(12):3821-38
11739783
J Cell Biol. 2002 Mar 18;156(6):1015-28
11889142
Mol Biol Cell. 2002 Apr;13(4):1238-51
11950935
Curr Biol. 2002 Jun 4;12(11):885-93
12062051
J Cell Biol. 2003 Mar 17;160(6):887-97
12642614
Nat Cell Biol. 2004 Jun;6(6):469-72
15170453
Mol Biol Cell. 2004 Jul;15(7):3031-41
15107463
Mol Biol Cell. 2004 Aug;15(8):3553-66
15155809
J Bacteriol. 1983 Jan;153(1):163-8
6336730
Gene. 1987;57(2-3):267-72
3319781
Genetics. 1989 May;122(1):19-27
2659436
EMBO J. 1989 Aug;8(8):2241-50
2676517
Science. 1993 Apr 2;260(5104):88-91
8385367
J Cell Biol. 1994 Nov;127(3):653-65
7962050
J Cell Biol. 1995 Mar;128(5):779-92
7533169
Mol Biol Cell. 1995 May;6(5):525-39
7663021
J Cell Biol. 1997 Aug 11;138(3):517-29
9245783
Mol Biol Cell. 1997 Nov;8(11):2307-27
9362071
Biochem Soc Trans. 1999 Aug;27(4):662-6
10917662