Acyl-CoA-binding protein, Acb1p, is required for normal vacuole function and ceramide synthesis in Saccharomyces cerevisiae.
In the present study, we show that depletion of acyl-CoA-binding protein, Acb1p, in yeast affects ceramide levels, protein trafficking, vacuole fusion and structure. Vacuoles in Acb1p-depleted cells are multi-lobed, contain significantly less of the SNAREs (soluble N -ethylmaleimide-sensitive fusion protein attachment protein receptors) Nyv1p, Vam3p and Vti1p, and are unable to fuse in vitro. Mass spectrometric analysis revealed a dramatic reduction in the content of ceramides in whole-cell lipids and in vacuoles isolated from Acb1p-depleted cells. Maturation of yeast aminopeptidase I and carboxypeptidase Y is slightly delayed in Acb1p-depleted cells, whereas the maturation of alkaline phosphatase and Gas1p is unaffected. The fact that Gas1p maturation is unaffected by Acb1p depletion, despite the lowered ceramide content in these cells, indicates that ceramide synthesis in yeast could be compartmentalized. We suggest that the reduced ceramide synthesis in Acb1p-depleted cells leads to severely altered vacuole morphology, perturbed vacuole assembly and strong inhibition of homotypic vacuole fusion.
Faergeman
Nils J
NJ
Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
Feddersen
Søren
S
Christiansen
Janne K
JK
Larsen
Morten K
MK
Schneiter
Roger
R
Ungermann
Christian
C
Mutenda
Kudzai
K
Roepstorff
Peter
P
Knudsen
Jens
J
D002352:Carrier Proteins / Q000502:physiology*; D002518:Ceramides / Q000096:biosynthesis* / Q000172:deficiency / Q000378:metabolism; D026261:Diazepam Binding Inhibitor / Q000378:metabolism*; D008561:Membrane Fusion / Q000502:physiology; D009154:Mutation / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism / Q000502:physiology*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D014617:Vacuoles / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*
C492820:ACB1 protein, S cerevisiae; D002352:Carrier Proteins; D002518:Ceramides; D026261:Diazepam Binding Inhibitor; D029701:Saccharomyces cerevisiae Proteins