Campagnaro Gustavo D, Elati Hamza A A, Balaska Sofia, Martin Abril Maria Esther, Natto Manal J, Hulpia Fabian, Lee Kelly, Sheiner Lilach, Van Calenbergh Serge, de Koning Harry P
Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, UK.
Laboratory for Medicinal Chemistry, Campus Heymans, Ghent University, Ottergemsesteenweg 460, B-9000 Gent, Belgium.
Int J Mol Sci. 2022 Jan 10;23(2):710. doi: 10.3390/ijms23020710.
is unable to synthesize purines de novo, instead salvages them from its environment, inside the host cell, for which they need high affinity carriers. Here, we report the expression of a Equilibrative Nucleoside Transporter, Tg244440, in a strain from which nucleobase transporters have been deleted. Tg244440 transported hypoxanthine and guanine with similar affinity ( ~1 µM), while inosine and guanosine displayed values of 4.05 and 3.30 µM, respectively. Low affinity was observed for adenosine, adenine, and pyrimidines, classifying Tg244440 as a high affinity oxopurine transporter. Purine analogues were used to probe the substrate-transporter binding interactions, culminating in quantitative models showing different binding modes for oxopurine bases, oxopurine nucleosides, and adenosine. Hypoxanthine and guanine interacted through protonated N1 and N9, and through unprotonated N3 and N7 of the purine ring, whereas inosine and guanosine mostly employed the ribose hydroxy groups for binding, in addition to N1H of the nucleobase. Conversely, the ribose moiety of adenosine barely made any contribution to binding. is the first gene identified to encode a high affinity oxopurine transporter in and, to the best of our knowledge, the first purine transporter to employ different binding modes for nucleosides and nucleobases.
无法从头合成嘌呤，而是从其环境中，即宿主细胞内挽救嘌呤，为此它们需要高亲和力载体。在此，我们报道了一种平衡核苷转运蛋白Tg244440在一个已缺失核碱基转运蛋白的菌株中的表达。Tg244440以相似的亲和力（约1μM）转运次黄嘌呤和鸟嘌呤，而肌苷和鸟苷的Kₘ值分别为4.05和3.30μM。对腺苷、腺嘌呤和嘧啶观察到低亲和力，将Tg244440归类为高亲和力氧嘌呤转运蛋白。使用嘌呤类似物来探测底物 - 转运蛋白的结合相互作用，最终得到定量模型，该模型显示了氧嘌呤碱基、氧嘌呤核苷和腺苷的不同结合模式。次黄嘌呤和鸟嘌呤通过嘌呤环的质子化N1和N9以及未质子化的N3和N7相互作用，而肌苷和鸟苷除了碱基的N1H外，大多利用核糖羟基进行结合。相反，腺苷的核糖部分对结合几乎没有任何贡献。Tg244440是在[具体物种名称未给出]中鉴定出的第一个编码高亲和力氧嘌呤转运蛋白的基因，据我们所知，也是第一个对核苷和核碱基采用不同结合模式的嘌呤转运蛋白。
