Revisiting N-glycosylation in Halobacterium salinarum: Characterizing a dolichol phosphate- and glycoprotein-bound tetrasaccharide.
Revisiting N-glycosylation in Halobacterium salinarum: Characterizing a dolichol phosphate- and glycoprotein-bound tetrasaccharide.
复制标题
重新审视盐杆菌中的 N-糖基化：表征磷酸多醇和糖蛋白结合的四糖。
DOI：
10.1093/glycob/cwab080
复制
发表时间：
2021
期刊：
影响因子：
4.3
通讯作者：
Eichler,Jerry
中科院分区：
文献类型：
--
作者：
Vershinin,Zlata;Zaretsky,Marianna;Guan,Ziqiang;Eichler,Jerry
虽然盐生盐杆菌提供了真核生物外的第一个N-糖基化的例子，但在这种嗜盐古菌中，关于这种翻译后修饰的许多情况仍然不清楚或未知。修饰S层糖蛋白和古菌素的N-连接聚糖的组成提供了一个这样的例子。最初描述于大约40年前，从那时起的报告已经提出了关于这种聚糖的组成的矛盾发现，以及蛋白质结合聚糖和连接到其组装的脂质上的聚糖版本之间的差异。为了澄清这些问题，本文采用液相色谱-电喷雾电离质谱法重新研究了该聚糖在与靶蛋白的选定天冬酰胺残基连接时以及与组装聚糖的脂质多萜醇磷酸结合时的组成。这些努力揭示了N-连接的聚糖对应于包含己糖、硫酸化己糖醛酸、己糖醛酸和第二硫酸化己糖醛酸的四糖。当连接到多萜醇磷酸而不是蛋白质时，相同的四糖在最终的糖上被甲基化。此外，在寡糖基转移酶AglB不存在的情况下，存在多萜醇磷酸连接的甲基化和二硫酸化四糖的积累。了解这种聚糖在脂质和蛋白质结合阶段的组成，以及操纵Hbt的基因缺失方法的可用性。salinarum，将允许描绘该生物体中的N-糖基化途径。
AlthoughHalobacterium salinarumprovided the first example of N-glycosylation outside the Eukarya, much regarding such post-translational modification in this halophilic archaea remains either unclear or unknown. The composition of anN-linked glycan decorating both the S-layer glycoprotein and archaellins offers one such example. Originally described some 40 years ago, reports from that time on have presented conflicted findings regarding the composition of this glycan, as well as differences between the protein-bound glycan and that version of the glycan attached to the lipid upon which it is assembled. To clarify these points, liquid chromatography-electrospray ionization mass spectrometry was employed here to revisit the composition of this glycan both when attached to selected asparagine residues of target proteins and when bound to the lipid dolichol phosphate upon which the glycan is assembled. Such efforts revealed theN-linked glycan as corresponding to a tetrasaccharide comprising a hexose, a sulfated hexuronic acid, a hexuronic acid and a second sulfated hexuronic acid. When attached to dolichol phosphate but not to proteins, the same tetrasaccharide is methylated on the final sugar. Moreover, in the absence of the oligosaccharyltransferase AglB, there is an accumulation of the dolichol phosphate-linked methylated and disulfated tetrasaccharide. Knowing the composition of this glycan at both the lipid- and protein-bound stages, together with the availability of gene deletion approaches for manipulatingHbt. salinarum, will allow delineation of the N-glycosylation pathway in this organism.