Department of Biochemistry and Molecular Biology and Centre for Blood Research, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8N 3ZS, Canada.
J Struct Biol. 2021 Jun;213(2):107733. doi: 10.1016/j.jsb.2021.107733. Epub 2021 Apr 2.
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），这是一种与毒力和调节包括细胞分裂在内的基本生理过程相关的聚合物。CDP-核糖醇是核糖醇磷酸聚合的激活前体，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，我们展示了金黄色葡萄球菌 TarI 和 TarJ 的apo 形式以及与底物和产物结合的复合物的晶体结构。TarI 结构说明了从 CTP 和核糖醇磷酸合成 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 的结构提供了关于核糖醇磷酸还原为核糖醇磷酸的上游步骤的见解。此外，我们使用交联质谱分析的约束提出了一个由四聚体形式构建的酶的一般拓扑结构。总之，我们的数据提供了 CDP-核糖醇产生的分子细节，这可能有助于设计针对 WTA 生物合成的抑制剂。
