Mai1p is essential for maturation of proaminopeptidase I but not for autophagy.
We here identify Mai1p, a homologue of the autophagy protein Aut10p, as a novel component essential for proaminopeptidase I (proAPI) maturation under non-starvation conditions. In mai1Delta cells mature vacuolar proteinases are detectable and vacuolar acidification is normal. In mai1Delta cells autophagy occurs, though at a somewhat reduced level. This is indicated by proAPI maturation during starvation and accumulation of autophagic bodies during starvation with phenylmethylsulfonyl fluoride. Homozygous diploid mai1Delta cells sporulate, but with a slightly reduced frequency. Biologically active Ha-tagged Mai1p, chromosomally expressed under its native promoter, is at least in part peripherally membrane-associated. In indirect immunofluorescence it localizes to the vacuolar membrane or structures nearby. In some cells Ha-tagged Mai1p appears concentrated at regions adjacent to the nucleus.
Barth
Henning
H
University of Stuttgart, Institute of Biochemistry, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
Meiling-Wesse
Khuyen
K
Epple
Ulrike D
UD
Thumm
Michael
M
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000378:metabolism*; D001343:Autophagy / Q000502:physiology*; D000071183:Autophagy-Related Proteins; D002451:Cell Compartmentation; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014617:Vacuoles / Q000201:enzymology
C441008:ATG18 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D008565:Membrane Proteins; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; C450423:ATG21 protein, S cerevisiae; D010450:Endopeptidases; D000626:Aminopeptidases; C450422:proaminopeptidase I