Cytoplasmic and mitochondrial forms of yeast adenylate kinase 2 are N-acetylated.
Yeast major adenylate kinase (Aky2p), encoded by a single gene, occurs in two subcellular compartments, mitochondria and cytoplasm. Only 6-8% of the protein which has no cleavable presequence is imported into the organelle (Bandlow et al. (1988) Eur. J. Biochem. 178, 451-457). In the wild type two AKY2-derived signals (a major and a minor one) were detected by a monospecific antibody after two-dimensional gel electrophoresis and Western blotting. The signals reflected identical electrophoretic mobilities and were absent from an AKY2-disrupted strain suggesting that they were due to differently modified forms of Aky2p. Two similar signals were found in a mutant defective in protein N-acetylation, however, the pI values of both spots were shifted towards alkaline pH by one charge. This indicated that both forms of Aky2p were N-acetylated in the wild type and that their charge difference was not caused by incomplete N-acetylation. This observation furthermore suggested that, in the wild type, two different modifications exist one of which is N-acetylation. The second modification remains unidentified. We analysed the influence of protein N-acetylation on mitochondrial import. Both versions of Aky2p occurred in the cytoplasm and in mitochondria. Their proportion was unchanged in the N-acetylation mutant showing that neither modification affected the efficiency of import of adenylate kinase into mitochondria. It is discussed that N-acetylation occurs during or immediately after translation in the cytoplasm so that import of adenylate kinase may ensue co-translationally.
Klier
H
H
Max-Planck-Institut für Biochemie, Martinsried, Germany.
Magdolen
V
V
Schricker
R
R
Strobel
G
G
Lottspeich
F
F
Bandlow
W
W
D000107:Acetylation; D000263:Adenylate Kinase / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D003593:Cytoplasm / Q000201:enzymology*; D015180:Electrophoresis, Gel, Two-Dimensional; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
D007527:Isoenzymes; D000263:Adenylate Kinase