| Autor: |
Lanz, Nicholas D., Ming, Shonoi A., Thon, Vireak, Veeramachineni, Vamsee M., Azurmendi, Hugo F., Vann, Willie F. |
| Zdroj: |
Biochemistry; June 2021, Vol. 60 Issue: 25 p2044-2054, 11p |
| Abstrakt: |
Antiphagocytic capsular polysaccharides are key components of effective vaccines against pathogenic bacteria. Neisseria meningitidisgroups B and C, as well as Escherichia coliserogroups K1 and K92, are coated with polysialic acid capsules. Although the chemical structure of these polysaccharides and the organization of the associated gene clusters have been described for many years, only recently have the details of the biosynthetic pathways been discovered. The polysialic acid chains are synthesized by polysialyltransferases on a proposed phosphatidylglycerol lipid acceptor with a poly keto-deoxyoctulosonate (KDO) linker. Synthesis of this acceptor requires at least three enzymes in E. coliK1: KpsS, KpsC, and NeuE. In this report, we have characterized the β-KDO glycosyltransferase KpsS, the first enzyme in the pathway for lipid acceptor synthesis. After purification of KpsS in a soluble active form, we investigated its function and substrate specificity and showed that KpsS can transfer a KDO residue to a fluorescently labeled phosphatidylglycerol lipid. The enzyme tolerated various lengths of fatty acid acyl chains on the phosphatidylglycerol, including fluorescent tags, but exhibited a preference for phosphatidylglycerol diacylated with longer fatty acid chains as indicated by the smaller Kdand Kmvalues for substrates with chains with more than 14 members. Additional structural analysis of the KpsS product confirmed that KpsS transfers KDO from CMP-KDO to the 1-hydroxyl of phosphatidylglycerol to form a β-KDO linkage. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
