A N(alpha)-acetyltransferase selectively transfers an acetyl group to NH2-terminal methionine residues: purification and partial characterization.
Methionine N(alpha)-acetyltransferase (M-N(alpha)AT), which selectively catalyzes the transfer of an acetyl group from acetyl coenzyme A to the alpha-NH2 group of methionine residues in proteins and peptides, was isolated from Saccharomyces cerevisiae. The enzyme was purified 22000-fold to apparent homogeneity by successive purification steps using DEAE-Sepharose, DE-52 cellulose, CM-52 cellulose, Affi-Gel Blue gel and hydroxyapatite. The Mr of the native enzyme was estimated to be 70000 +/- 5000 by gel filtration chromatography. The enzyme has a pI near 8.3 as determined by chromatofocusing on Mono P. The enzyme catalyzed the transfer of an acetyl group to a synthetic peptide mimicking the first 24 residues of yeast proteinase A inhibitor 3 (Met-Asn-Thr...) and 3 of its 19 penultimately substituted analogues ([Asp2], [Glu2], and [Gln2]). Based on the estimated molecular weight and amino-acid sequence, The enzyme is different from two other recently identified methionine N(alpha)-acetyltransferases, NAT2 (Kulkarni, M.S. and Sherman, F. (1994) J. Biol. Chem. 269, 13141-13147) and MAK3 (Tercero, J.C. and Wickner, R.B. (1992) J. Biol. Chem. 267, 20277-20281). Among these three enzymes, M-N(alpha)AT and NAT2 have similar substrate specificity, however, only purified M-N(alpha)AT, but not recombinant NAT2 gene product, can catalyze the transfer of acetyl group to NH2-terminal methionine residues. The availability of this methionine N(alpha)-acetyltransferase will advance the understanding of protein co-translational processing.
Lee
F J
FJ
Department of Molecular Biology, Massachusetts General Hospital, Boston 02114, USA. fangjen@ntumc1.mc.ntu.edu.tw
Lin
L W
LW
Smith
J A
JA
D000107:Acetylation; D000595:Amino Acid Sequence; D001191:Arylamine N-Acetyltransferase / Q000302:isolation & purification / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D005800:Genes, Fungal; D008715:Methionine / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013379:Substrate Specificity
D005656:Fungal Proteins; D010455:Peptides; D008715:Methionine; D001191:Arylamine N-Acetyltransferase