Lipo-chitin oligosaccharides (LCOs) are novel bacterial glycolipid signal molecules that mediate the species--specific symbiosis between rhizobial bacteria and leguminous plants. Nodulation of the legume roots and nitrogen-fixation in the resulting nodules by Rhizobia is controlled by the bacterial nodulation genes that encode the LCO biosynthetic enzymes. The length of the LCO chitin backbone, the length and degree of unsaturation of the fatty acyl chain attached to it, and the combination of different chemical substituents on the reducing- and nonreducing-terminal residues all contribute to the species--specificity of the signal. LCOs are bioactive in the nanomolar and subnanomolar concentration range and are produced as heterogeneous mixtures, making determination of their structures a difficult task, most successfully approached by the application of modern mass spectrometric methods in combination with specific chemical treatments aimed at identifying specific chemical moieties. This review presents an overview of these methods as they are being used for the structural elucidation of LCOs, and discusses the role of structural diversity in mediating species-specificity.

中文翻译：

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脂质甲壳质寡糖的质谱分析-信号分子介导宿主特异性的豆科植物-根瘤菌共生。

脂壳多糖低聚糖（LCO）是新型细菌糖脂信号分子，可介导根瘤菌和豆科植物之间的物种特异性共生。根瘤菌对豆科植物根瘤和根瘤中氮的固定受编码LCO生物合成酶的细菌根瘤基因控制。LCO几丁质骨架的长度，与其相连的脂肪酰基链的不饱和长度和程度，以及还原和非还原末端残基上不同化学取代基的组合均对信号的物种特异性有所贡献。LCO在纳摩尔和亚纳摩尔浓度范围内具有生物活性，并且以异质混合物形式产生，因此很难确定其结构，最成功的方法是将现代质谱方法与旨在识别特定化学部分的特定化学处理相结合。这篇综述概述了这些方法，这些方法正用于LCO的结构阐明，并讨论了结构多样性在介导物种特异性中的作用。