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Crystal structures of sialyltransferase from Photobacterium damselae
- Huynh, Nhung, Li, Yanhong, Yu, Hai, Huang, Shengshu, Lau, Kam, Chen, Xi, Fisher, Andrew J.
- FEBS letters 2014 v.588 no.24 pp. 4720-4729
- Photobacterium damselae, crystal structure, immunoglobulin A
- Sialyltransferase structures fall into either GT-A or GT-B glycosyltransferase fold. Some sialyltransferases from the Photobacterium genus have been shown to contain an additional N-terminal immunoglobulin (Ig)-like domain. Photobacterium damselae α2–6-sialyltransferase has been used efficiently in enzymatic and chemoenzymatic synthesis of α2–6-linked sialosides. Here we report three crystal structures of this enzyme. Two structures with and without a donor substrate analog CMP-3F(a)Neu5Ac contain an immunoglobulin (Ig)-like domain and adopt the GT-B sialyltransferase fold. The binary structure reveals a non-productive pre-Michaelis complex, which are caused by crystal lattice contacts that prevent the large conformational changes. The third structure lacks the Ig-domain. Comparison of the three structures reveals small inherent flexibility between the two Rossmann-like domains of the GT-B fold.