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Mai1p is essential for maturation of proaminopeptidase I but not for autophagy
Author(s) -
Barth Henning,
Meiling-Wesse Khuyen,
Epple Ulrike D.,
Thumm Michael
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)02252-4
Subject(s) - phenylmethylsulfonyl fluoride , autophagy , microbiology and biotechnology , vacuole , biology , immunofluorescence , nucleus , chemistry , biochemistry , genetics , antibody , apoptosis , phosphorylation , serine , cytoplasm
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 mai1 Δ cells mature vacuolar proteinases are detectable and vacuolar acidification is normal. In mai1 Δ 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 mai1 Δ 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.