鼠李糖相关分子引起了人们的注意,因为它们存在于细菌中,而不是哺乳动物中,使它们有可能用作抗菌剂。此外,它们对于肿瘤免疫疗法也很有价值。因此,有关含鼠李糖化合物的功能和生物合成途径的研究正在进行中。在本文中,关于三个鼠李糖供体的生物合成途径的研究,即,脱氧胸苷二磷酸-L-鼠李糖(dTDP-Rha),尿苷二磷酸-鼠李糖(UDP-Rha),和鸟苷二磷酸鼠李糖(GDP-Rha),首先回顾,以及这些相关酶的功能和晶体结构。其中,dTDP-Rha是最常见的鼠李糖供体,和四种酶,包括葡萄糖-1-磷酸胸苷酰转移酶RmlA,dTDP-Glc-4,6-脱水酶RmlB,dTDP-4-酮-6-脱氧-Glc-3,5-差向异构酶RmlC,和dTDP-4-酮-Rha还原酶RmlD,参与其生物合成。其次,来自嗜热脂肪土芽孢杆菌的几种已知的鼠李糖基转移酶,棘囊多孢菌,结核分枝杆菌,铜绿假单胞菌,和肺炎链球菌进行了讨论。在这些研究中,然而,通过使用基因敲除和放射性标记的底物来验证鼠李糖基转移酶的功能,几乎不可能获得和表征酶促反应的产物。最后,简要介绍了含鼠李糖化合物在疾病治疗中的应用。
Rhamnose-associated molecules are attracting attention because they are present in bacteria but not mammals, making them potentially useful as antibacterial agents. Additionally, they are also valuable for tumor immunotherapy. Thus, studies on the functions and biosynthetic pathways of rhamnose-containing compounds are in progress. In this paper, studies on the biosynthetic pathways of three rhamnose donors, i.e., deoxythymidinediphosphate-L-rhamnose (dTDP-Rha), uridine diphosphate-rhamnose (UDP-Rha), and guanosine diphosphate rhamnose (GDP-Rha), are firstly reviewed, together with the functions and crystal structures of those associated enzymes. Among them, dTDP-Rha is the most common rhamnose donor, and four enzymes, including glucose-1-phosphate thymidylyltransferase RmlA, dTDP-Glc-4,6-dehydratase RmlB, dTDP-4-keto-6-deoxy-Glc-3,5-epimerase RmlC, and dTDP-4-keto-Rha reductase RmlD, are involved in its biosynthesis. Secondly, several known rhamnosyltransferases from Geobacillus stearothermophilus, Saccharopolyspora spinosa, Mycobacterium tuberculosis, Pseudomonas aeruginosa, and Streptococcus pneumoniae are discussed. In these studies, however, the functions of rhamnosyltransferases were verified by employing gene knockout and radiolabeled substrates, which were almost impossible to obtain and characterize the products of enzymatic reactions. Finally, the application of rhamnose-containing compounds in disease treatments is briefly described.