Catalytic and glycan-binding abilities of ppGalNAc-T2 are regulated by acetylation

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• 作者：Natacha Zlocowski^a ; Victor G. Sendra^a ; Virginia Lorenz^a ; Marcos A. Villarreal^a ; Alberto Jorge^b ; Yolanda N&#xfa ; ñ ; ez^b ; Eric P. Bennett^c ; Henrik Clausen^c ; Gustavo A. Nores^a ; Fernando J. Irazoqui^a ; ^{irazoqui@dqb.fcq.unc.edu.ar" rel="nofollow}
• 关键词：Acetylation effect ; Glycosyltransferase activity ; Lectin domain
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2011
• 出版时间：24 June 2011
• 年：2011
• 卷：410
• 期：1
• 页码：140-145
• 全文大小：778 K
• ISSN：S0006291X11009004

文摘

Post-translational acetylation is an important molecular regulatory mechanism affecting the biological activity of proteins. Polypeptide GalNAc transferases (ppGalNAc-Ts) are a family of enzymes that catalyze initiation of mucin-type O-glycosylation. All ppGalNAc-Ts in mammals are type II transmembrane proteins having a Golgi lumenal region that contains a catalytic domain with glycosyltransferase activity, and a C-terminal R-type (“ricin-like”) lectin domain. We investigated the effect of acetylation on catalytic activity of glycosyltransferase, and on fine carbohydrate-binding specificity of the R-type lectin domain of ppGalNAc-T2. Acetylation effect on ppGalNAc-T2 biological activity in vitro was studied using a purified human recombinant ppGalNAc-T2. Mass spectrometric analysis of acetylated ppGalNAc-T2 revealed seven acetylated amino acids (K103, S109, K111, K363, S373, K521, and S529); the first five are located in the catalytic domain. Specific glycosyltransferase activity of ppGalNAc-T2 was reduced 95% by acetylation. The last two amino acids, K521 and S529, are located in the lectin domain, and their acetylation results in alteration of the carbohydrate-binding ability of ppGalNAc-T2. Direct binding assays showed that acetylation of ppGalNAc-T2 enhances the recognition to αGalNAc residue of MUC1αGalNAc, while competitive assays showed that acetylation modifies the fine GalNAc-binding form of the lectin domain. Taken together, these findings clearly indicate that biological activity (catalytic capacity and glycan-binding ability) of ppGalNAc-T2 is regulated by acetylation.