The cell wall of many pathogenic Gram-positive bacteria contains ribitol-phosphate wall teichoic acid (WTA), a polymer that is linked to virulence and regulation of essential physiological processes including cell division. CDP-ribitol, the activated precursor for ribitol-phosphate polymerization, is synthesized by a cytidylyltransferase and reductase pair known as TarI and TarJ, respectively. In this study, we present crystal structures of Staphylococcus aureus TarI and TarJ in their apo forms and in complex with substrates and products. The TarI structures illustrate the mechanism of CDP-ribitol synthesis from CTP and ribitol-phosphate and reveal structural changes required for substrate binding and catalysis. Insights into the upstream step of ribulose-phosphate reduction to ribitol-phosphate is provided by the structures of TarJ. Furthermore, we propose a general topology of the enzymes in a heterotetrameric form built using restraints from crosslinking mass spectrometry analysis. Together, our data present molecular details of CDP-ribitol production that may aid in the design of inhibitors against WTA biosynthesis.

许多致病性革兰氏阳性细菌的细胞壁含有核糖醇-磷酸壁磷壁酸 (WTA)，这是一种与毒力和包括细胞分裂在内的基本生理过程的调节有关的聚合物。CDP-核糖醇是核糖醇-磷酸聚合的活化前体，由胞苷酰转移酶和还原酶对分别称为 TarI 和 TarJ 合成。在这项研究中，我们介绍了金黄色葡萄球菌的晶体结构TarI 和 TarJ 的载脂蛋白形式并与底物和产物复合。TarI 结构说明了从 CTP 和核糖醇-磷酸酯合成 CDP-核糖醇的机制，并揭示了底物结合和催化所需的结构变化。TarJ 的结构提供了对磷酸核酮糖还原为磷酸核糖醇的上游步骤的见解。此外，我们提出了使用交联质谱分析的限制构建的异四聚体形式的酶的一般拓扑结构。总之，我们的数据提供了 CDP-核糖醇生产的分子细节，可能有助于设计 WTA 生物合成抑制剂。