crystal structure of legionella dotd insights into the relationship between type ivb and type iiiii secretion systems晶体结构的军团dotd洞察ivb和类型iiiii司长委任型分泌系统之间的关系.pdfVIP

Crystal Structure of Legionella DotD: Insights into the Relationship between Type IVB and Type II/III Secretion Systems 1 2 2 2 1 Noboru Nakano , Tomoko Kubori , Miki Kinoshita , Katsumi Imada *, Hiroki Nagai * 1 Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan, 2 Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan Abstract The Dot/Icm type IVB secretion system (T4BSS) is a pivotal determinant of Legionella pneumophila pathogenesis. L. pneumophila translocate more than 100 effector proteins into host cytoplasm using Dot/Icm T4BSS, modulating host cellular functions to establish a replicative niche within host cells. The T4BSS core complex spanning the inner and outer membranes is thought to be made up of at least five proteins: DotC, DotD, DotF, DotG and DotH. DotH is the outer membrane protein; its targeting depends on lipoproteins DotC and DotD. However, the core complex structure and ˚ assembly mechanism are still unknown. Here, we report the crystal structure of DotD at 2.0 A resolution. The structure of DotD is distinct from that of VirB7, the outer membrane lipoprotein of the type IVA secretion system. In contrast, the C- terminal domain of DotD is remarkably similar to the N-terminal subdomain of secretins, the integral outer membrane proteins that form substrate conduits for the type II and the type III secretion systems (T2SS and T3SS). A short b-segment in the otherwise disordered N-terminal region, located on the hydrophobic cleft of the C-terminal domain, is essential for oute