Glycopeptide-preferring Polypeptide GalNAc Transferase 10 (ppGalNAc T10), Involved in Mucin-type O-Glycosylation, Has a Unique GalNAc-O-Ser/Thr-binding Site in Its Catalytic Domain Not Found in ppGalNAc T1 or T2
Glycopeptide-preferring Polypeptide GalNAc Transferase 10 (ppGalNAc T10), Involved in Mucin-type O-Glycosylation, Has a Unique GalNAc-O-Ser/Thr-binding Site in Its Catalytic Domain Not Found in ppGalNAc T1 or T2
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DOI：
10.1074/jbc.m109.017236
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发表时间：
2009-07-24
影响因子：
4.8
通讯作者：
Gerken, Thomas A.
中科院分区：
文献类型：
--
作者：
Perrine, Cynthia L.;Ganguli, Anjali;Gerken, Thomas A.
粘蛋白型0-糖基化由UDP-GalNAc：多肽α-N-乙酰半乳糖胺转移酶（ppGalNAc Ts）的大家族起始，其将GalNAc从UDP-GalNAc转移到多肽受体的Ser和Thr残基。该家族的一些成员更喜欢先前糖基化的肽（ppGalNAc T7和T10），而其他成员则受到邻近糖基化的抑制（ppGalNAc T1和T2）。表征它们的肽和糖肽底物特异性对于理解每种亚型的生物学作用和意义至关重要。利用一系列随机肽和糖肽底物，我们已经获得了肽和糖肽特异性的ppGalNAc T10与ppGalNAc T1和T2的比较。对于糖肽底物，ppGalNAc T10在相对于Ser或Thr受体位点的+1（C-末端）位置处表现出对Ser/Thr-O-GalNAc的单一大偏好。ppGalNAc T1和T2显示没有显著的增强，表明Ser/Thr-O-GalNAc在大多数位置对这些亚型具有抑制作用。对随机肽底物，ppGalNAc T10显示没有显着的疏水性或亲水性残基的增强，与以往报道的ppGalNAc T1和T2。我们的研究结果表明，这些转移酶具有独特的肽和糖肽的偏好，证明了它们的底物多样性和它们可能的作用范围从启动转移酶到填充转移酶。
Mucin-type O-glycosylation is initiated by a large family of UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases (ppGalNAc Ts) that transfer GalNAc from UDP-GalNAc to the Ser and Thr residues of polypeptide acceptors. Some members of the family prefer previously glycosylated peptides (ppGalNAc T7 and T10), whereas others are inhibited by neighboring glycosylation (ppGalNAc T1 and T2). Characterizing their peptide and glycopeptide substrate specificity is critical for understanding the biological role and significance of each isoform. Utilizing a series of random peptide and glycopeptide substrates, we have obtained the peptide and glycopeptide specificities of ppGalNAc T10 for comparison with ppGalNAc T1 and T2. For the glycopeptide substrates, ppGalNAc T10 exhibited a single large preference for Ser/Thr-O-GalNAc at the +1 (C-terminal) position relative to the Ser or Thr acceptor site. ppGalNAc T1 and T2 revealed no significant enhancements suggesting Ser/Thr-O-GalNAc was inhibitory at most positions for these isoforms. Against random peptide substrates, ppGalNAc T10 revealed no significant hydrophobic or hydrophilic residue enhancements, in contrast to what has been reported previously for ppGalNAc T1 and T2. Our results reveal that these transferases have unique peptide and glycopeptide preferences demonstrating their substrate diversity and their likely roles ranging from initiating transferases to filling-in transferases.