Schoenhofen Ian C, Vinogradov Evgeny, Whitfield Dennis M, Brisson Jean-Robert, Logan Susan M
Institute for Biological Sciences, National Research Council, Ottawa, Ontario, K1A 0R6 Canada.
Glycobiology. 2009 Jul;19(7):715-25. doi: 10.1093/glycob/cwp039. Epub 2009 Mar 12.
The sialic acid-like sugar 5,7-diacetamido-3,5,7,9-tetradeoxy-D-glycero-D-galacto-nonulosonic acid, or legion-aminic acid, is found as a virulence-associated cell-surface glycoconjugate in the Gram-negative bacteria Legionella pneumophila and Campylobacter coli. L. pneumophila serogroup 1 strains, causative agents of Legionnaire's disease, contain an alpha2,4-linked homopolymer of legionaminic acid within their lipopolysaccharide O-chains, whereas the gastrointestinal pathogen C. coli modifies its flagellin with this monosaccharide via O-linkage. In this work, we have purified and biochemically characterized 11 candidate biosynthetic enzymes from Campylobacter jejuni, thereby fully reconstituting the biosynthesis of legionaminic acid and its CMP-activated form, starting from fructose-6-P. This pathway involves unique GDP-linked intermediates, likely providing a cellular mechanism for differentiating between this and similar UDP-linked pathways, such as UDP-2,4-diacetamido-bacillosamine biosynthesis involved in N-linked protein glycosylation. Importantly, these findings provide a facile method for efficient large-scale synthesis of legionaminic acid, and since legionaminic acid and sialic acid share the same D-glycero-D-galacto absolute configuration, this sugar may now be evaluated for its potential as a sialic acid mimic.
唾液酸样糖5,7-二乙酰氨基-3,5,7,9-四脱氧-D-甘油-D-半乳糖壬酮糖酸，即军团氨糖酸，在革兰氏阴性菌嗜肺军团菌和空肠弯曲菌中作为一种与毒力相关的细胞表面糖缀合物被发现。嗜肺军团菌血清1型菌株是军团病的病原体，在其脂多糖O链中含有α2,4-连接的军团氨糖酸同聚物，而肠道病原体空肠弯曲菌则通过O-连接用这种单糖修饰其鞭毛蛋白。在这项工作中，我们从空肠弯曲菌中纯化并对11种候选生物合成酶进行了生化表征，从而从6-磷酸果糖开始完全重建了军团氨糖酸及其CMP活化形式的生物合成。该途径涉及独特的GDP连接中间体，可能为区分该途径与类似的UDP连接途径提供一种细胞机制，例如参与N-连接蛋白糖基化的UDP-2,4-二乙酰氨基杆菌糖胺生物合成。重要的是，这些发现为军团氨糖酸的高效大规模合成提供了一种简便方法。而且由于军团氨糖酸和唾液酸具有相同的D-甘油-D-半乳糖绝对构型，现在可以评估这种糖作为唾液酸模拟物的潜力。
