Cytoplasm-to-vacuole targeting and autophagy employ the same machinery to deliver proteins to the yeast vacuole.
The vacuolar protein aminopeptidase I (API) uses a novel cytoplasm-to-vacuole targeting (Cvt) pathway. Complementation analysis of yeast mutants defective for cytoplasm-to-vacuole protein targeting (cvt) and autophagy (apg) revealed seven overlapping complementation groups between these two sets of mutants. In addition, all 14 apg complementation groups are defective in the delivery of API to the vacuole. Similarly, the majority of nonoverlapping cvt complementation groups appear to be at least partially defective in autophagy. Kinetic analyses of protein delivery rates indicate that autophagic protein uptake is induced by nitrogen starvation, whereas Cvt is a constitutive biosynthetic pathway. However, the machinery governing Cvt is affected by nitrogen starvation as targeting defects resulting from API overexpression can be rescued by induction of autophagy.
Section of Microbiology, University of California, Davis, CA 95616, USA.
S V
SV
Scott
A
A
Hefner-Gravink
K A
KA
Morano
T
T
Noda
Y
Y
Ohsumi
D J
DJ
Klionsky
D000626:Aminopeptidases / Q000378:metabolism*; D001343:Autophagy; D003593:Cytoplasm / Q000378:metabolism*; D005816:Genetic Complementation Test; D005838:Genotype; D007700:Kinetics; D009584:Nitrogen / Q000378:metabolism; D010641:Phenotype; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D025262:Vacuolar Proton-Translocating ATPases; D014617:Vacuoles / Q000378:metabolism*
D029701:Saccharomyces cerevisiae Proteins; D000626:Aminopeptidases; C019689:APE1 protein, S cerevisiae; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; D009584:Nitrogen