Crystal Structure of Legionella DotD: Insights into the Relationship between Type IVB and Type II/III Secretion Systems

PLoS Pathogens

Tomoko Kubori¹  Miki Kinoshita¹  Katsumi Imada¹  Hiroki Nagai²  Noboru Nakano² 

[1] Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan;Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan

关键词: Outer membrane proteins;    Secretion systems;    Secretin;    Crystal structure;    Legionella pneumophila;    Bacterial pathogens;    Membrane protein complexes;    Sucrose;   

DOI  :  10.1371/journal.ppat.1001129

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

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 Å 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 β-segment in the otherwise disordered N-terminal region, located on the hydrophobic cleft of the C-terminal domain, is essential for outer membrane targeting of DotH and Dot/Icm T4BSS core complex formation. These findings uncover an intriguing link between T4BSS and T2SS/T3SS.

【 授权许可】

CC BY