Characterization of a Unique Tetrasaccharide and Distinct Glycoproteome in the O-Linked Protein Glycosylation System of Neisseria elongata subsp glycolytica
Characterization of a Unique Tetrasaccharide and Distinct Glycoproteome in the O-Linked Protein Glycosylation System of Neisseria elongata subsp glycolytica
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DOI：
10.1128/jb.00620-15
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发表时间：
2016-01-01
影响因子：
3.2
通讯作者：
Koomey, Michael
中科院分区：
文献类型：
--
作者：
Anonsen, Jan Haug;Vik, Ashild;Koomey, Michael
广谱O-连接蛋白糖基化在对人类健康和疾病具有重要意义的主要奈瑟氏菌属物种中得到了很好的表征。淋病奈瑟菌（Neisseria gonorrhoeae）、淋病奈瑟菌（N. meningitidis和N.尽管菌株内和菌株间存在变异性，但内酰胺、蛋白糖基化（PGL）基因内容和相应的寡糖结构相当保守。然而，这种系统在远亲物种中的地位在很大程度上仍未被探索。使用一株深分枝的长奈瑟氏球菌亚种（Neisseria elongata subsp.糖酵解菌，一种迄今未被认识的由二-N-乙酰基杆菌胺-葡萄糖-二-N-乙酰基己糖醛酸-N-乙酰基己糖胺（diNAcBac-Glc-diNAcHexA-HexNAc）组成的四糖糖型。定向诱变、质谱分析和聚糖血清分型证实，该寡糖是N.淋病奈瑟菌和淋病奈瑟菌。由PglB、PglC和PglD以及葡糖基转移酶PglH直向同源物的连续作用产生的脑膜炎。此外，在广泛保守但神秘的pglG基因的直向同源物中的无效突变阻止了扩展糖型的表达，提供了其产物是功能性糖基转移酶的第一个证据。尽管有大量的糖蛋白底物的明确证据，内源性IV型菌毛的主要菌毛蛋白亚基没有糖基化。后者的发现提出了明显的问题，菌毛蛋白糖基化的相对分布内的属，蛋白质糖基化底物是如何选择的，以及广谱蛋白质糖基化的整体结构-功能关系。总之，本研究的结果提供了一个基础上，以评估奈瑟球菌O-连接蛋白糖基化的多样性在属的水平。
Broad-spectrum O-linked protein glycosylation is well characterized in the major Neisseria species of importance to human health and disease. Within strains of Neisseria gonorrhoeae, N. meningitidis, and N. lactamica, protein glycosylation (pgl) gene content and the corresponding oligosaccharide structure are fairly well conserved, although intra-and interstrain variability occurs. The status of such systems in distantly related commensal species, however, remains largely unexplored. Using a strain of deeply branching Neisseria elongata subsp. glycolytica, a heretofore unrecognized tetrasaccharide glycoform consisting of di-Nacetylbacillosamine- glucose-di-N-acetyl hexuronic acid-N-acetylhexosamine (diNAcBac-Glc-diNAcHexA-HexNAc) was identified. Directed mutagenesis, mass spectrometric analysis, and glycan serotyping confirmed that the oligosaccharide is an extended version of the diNAcBac-Glc-based structure seen in N. gonorrhoeae and N. meningitidis generated by the successive actions of PglB, PglC, and PglD and glucosyltransferase PglH orthologues. In addition, a null mutation in the orthologue of the broadly conserved but enigmatic pglG gene precluded expression of the extended glycoform, providing the first evidence that its product is a functional glycosyltransferase. Despite clear evidence for a substantial number of glycoprotein substrates, the major pilin subunit of the endogenous type IV pilus was not glycosylated. The latter finding raises obvious questions as to the relative distribution of pilin glycosylation within the genus, how protein glycosylation substrates are selected, and the overall structure-function relationships of broad-spectrum protein glycosylation. Together, the results of this study provide a foundation upon which to assess neisserial O-linked protein glycosylation diversity at the genus level.