Dhariwal K R, Liav A, Vatter A E, Dhariwal G, Goren M B
J Bacteriol. 1986 Oct;168(1):283-93. doi: 10.1128/jb.168.1.283-293.1986.
The simple apolar C-mycosides, i.e., structurally well-defined hydrophobic glycopeptidolipids of several Mycobacterium species (see diagram below), were earlier shown to behave as receptors for adsorption of mycobacteriophage D4. This phage is usually virulent for Mycobacterium smegmatis. More complex, polar C-mycosides with additional carbohydrate substituents attached solely to the deoxytalose have recently been described. They are the highly specific serotyping antigens discovered by W. B. Schaefer--lipids which characterize members of the Mycobacterium avium-Mycobacterium intracellulare-Mycobacterium scrofulaceum (MAIS) complex. Both kinds are depicted in the structure below: (Formula: see text) where X equals H (for simple, apolar C-mycosides) and X equals small oligosaccharides (for antigenic forms; more complex, polar C-mycosides). The present investigations showed that the purified polar antigenic lipids exhibit considerably less adsorptive activity for D4 than do the apolar C-mycosides. Thus, the haptenic oligosaccharides are believed to shield the site in the molecule that the phage recognizes, and the blocking is reinforced by the specific antibodies that the antigens elicit. Although the MAIS serovars usually also produce the phage-reactive apolar C-mycosides, they are not permissive hosts for D4, nor do whole cells adsorb the phage. We suggest that in these species the apolar forms are probably "covered" at the cell surface by the antigenic lipids. Therefore, these antigenic mycosides may play a putative role in virulence of the MAIS members by protecting these mycobacteria from their own potential pathogen. The results of chemical transformations at specific sites of the mycoside core coupled with studies of simple synthetic lipid glycosides indicated that the principal phage receptor activity resides in the terminal methylated rhamnose (see diagram). It is this sugar which is evidently masked by the (seemingly remote) haptenic oligosaccharides.
简单的非极性C-霉菌糖苷，即几种分枝杆菌属结构明确的疏水糖肽脂（见下图），早期研究表明其可作为吸附分枝杆菌噬菌体D4的受体。这种噬菌体通常对耻垢分枝杆菌具有毒性。最近还描述了更复杂的极性C-霉菌糖苷，其额外的碳水化合物取代基仅连接到脱氧塔罗糖上。它们是W. B. 谢弗发现的高度特异性血清分型抗原——这些脂质是鸟分枝杆菌-胞内分枝杆菌-瘰疬分枝杆菌（MAIS）复合体成员的特征。两种类型如下所示：（分子式：见正文）其中X等于H（对于简单的非极性C-霉菌糖苷），X等于小寡糖（对于抗原形式；更复杂的极性C-霉菌糖苷）。目前的研究表明，纯化的极性抗原脂质对D4的吸附活性远低于非极性C-霉菌糖苷。因此，推测半抗原寡糖屏蔽了噬菌体识别的分子位点，并且抗原引发的特异性抗体增强了这种阻断作用。尽管MAIS血清型通常也产生与噬菌体反应的非极性C-霉菌糖苷，但它们不是D4的允许宿主，全细胞也不吸附该噬菌体。我们认为，在这些物种中，非极性形式可能在细胞表面被抗原脂质“覆盖”。因此，这些抗原性霉菌糖苷可能通过保护这些分枝杆菌免受自身潜在病原体的侵害，在MAIS成员的毒力中发挥假定作用。霉菌糖苷核心特定位点的化学转化结果以及简单合成脂质糖苷的研究表明，主要的噬菌体受体活性存在于末端甲基化鼠李糖中（见下图）。显然正是这种糖被（看似遥远的）半抗原寡糖所掩盖。
