State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, China.
Centre for Infectious Diseases Research, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China; Center for Structural Biology, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, China.
Mol Cell. 2014 Sep 18;55(6):931-937. doi: 10.1016/j.molcel.2014.08.001. Epub 2014 Sep 4.
Cyclic dinucleotides are a newly expanded class of second messengers that contribute to the regulation of multiple different pathways in bacterial, eukaryotic, and archaeal cells. The recently identified Vibrio cholerae dinucleotide cyclase (DncV, the gene product of VC0179) can generate three different cyclic dinucleotides and preferentially synthesize a hybrid cyclic-GMP-AMP. Here, we report the crystal structural and functional studies of DncV. We unexpectedly observed a 5-methyltetrahydrofolate diglutamate (5MTHFGLU2) molecule bound in a surface pocket opposite the nucleotide substrate-binding groove of DncV. Subsequent mutagenesis and functional studies showed that the enzymatic activity of DncV is regulated by folate-like molecules, suggesting the existence of a signaling pathway that links folate-like metabolism cofactors to the regulation of cyclic dinucleotide second messenger synthesis. Sequence analysis showed that the residues involved in 5MTHFGLU2 binding are highly conserved in DncV orthologs, implying the presence of this regulation mechanism in a wide variety of bacteria.
环二核苷酸是一类新发现的第二信使，参与细菌、真核生物和古菌细胞中多种不同途径的调节。最近发现的霍乱弧菌环二核苷酸环化酶（DncV，即 VC0179 基因产物）可以生成三种不同的环二核苷酸，并优先合成一种混合环-GMP-AMP。在这里，我们报告了 DncV 的晶体结构和功能研究。我们出人意料地观察到一个 5-甲基四氢叶酸二谷氨酸盐（5MTHFGLU2）分子结合在 DncV 的核苷酸底物结合槽对面的表面口袋中。随后的突变和功能研究表明，DncV 的酶活性受叶酸样分子的调节，这表明存在一种信号通路，将叶酸样代谢辅因子与环二核苷酸第二信使合成的调节联系起来。序列分析表明，参与 5MTHFGLU2 结合的残基在 DncV 同源物中高度保守，这意味着这种调节机制存在于各种各样的细菌中。
