On December 2, 2015. Prof. Delin You’s Group published a research article entitled "DndEi exhibits helicase activity essential for DNA phosphorothioate modification and ATPase activity strongly stimulated by DNA substrate with a GAAC/GTTC motif" in the Journal of Biological Chemistry.

Phosphorothioate (PT) modification of DNA, in which the non-bridging oxygen of the backbone phosphate group is replaced by sulfur, is governed by the DndA-E proteins in prokaryotes. To better understand the biochemical mechanism of PT modification, functional analysis of the recently found PT-modifying enzyme DndEi, which has an additional domain compared to canonical DndE, from Riemerella anatipestifer is performed by Delin You’s Group. The additional domain is identified as a DNA helicase, and functional deletion of this domain in vivo leads to PT modification deficiency, indicating an essential role of helicase activity in PT modification. Subsequent analysis reveals that the additional domain has an ATPase activity. Intriguingly, the ATPase activity is strongly stimulated by DNA substrate containing a GAAC/GTTC motif (i.e., the motif at which PT modifications occur in R. anatipestifer) when the additional domain and the other domain (homologous to canonical DndE) are co-expressed as a full-length DndEi. Prof. Delin You Group’s research results reveal that PT modification is a biochemical process with DNA strands separation and intense ATP hydrolysis.

PhD students Tao Zheng is the first author of this article. Dr. Qinghai Hu from the Chinese Academy of Agricultural Sciences is the corresponding author. This research was supported by grants from the National Science Foundation of China, the Ministry of Science and Technology, Shanghai Pujiang Program from the Shanghai Municipal Council of Science and Technology.