biostudies-literatureUnknownDutka PNIAID NIH HHSMedical Research CouncilThe <i>Legionella pneumophila</i> Dot/Icm type IV secretion system (T4SS) delivers effector proteins into host cells during infection. Despite its significance as a potential drug target, our current understanding of its atomic structure is limited to isolated subcomplexes. In this study, we used subtomogram averaging and integrative modeling to construct a nearly-complete model of the Dot/Icm T4SS accounting for seventeen protein components. We locate and provide insights into the structure and function of six new components including DotI, DotJ, DotU, IcmF, IcmT, and IcmX. We find that the cytosolic N-terminal domain of IcmF, a key protein forming a central hollow cylinder, interacts with DotU, providing insight into previously uncharacterized density. Furthermore, our model, in combinatbioRxiv : the preprint server for biology2023.03.22.533729https://www.ebi.ac.uk/biostudies/studies/S-EPMC10055428biostudies-literatureStructure and Function of the Dot/Icm T4SS.PMC10055428R01 AI127401MR/W010690/1Liu YJensen GJGhosal DCarter SDVijayrajratnam SZhao WMaggi SDutka PWang JVogel JPfalseStructure and Function of the Dot/Icm T4SS.The <i>Legionella pneumophila</i> Dot/Icm type IV secretion system (T4SS) delivers effector proteins into host cells during infection. Despite its significance as a potential drug target, our current understanding of its atomic structure is limited to isolated subcomplexes. In this study, we used subtomogram averaging and integrative modeling to construct a nearly-complete model of the Dot/Icm T4SS accounting for seventeen protein components. We locate and provide insights into the structure and function of six new components including DotI, DotJ, DotU, IcmF, IcmT, and IcmX. We find that the cytosolic N-terminal domain of IcmF, a key protein forming a central hollow cylinder, interacts with DotU, providing insight into previously uncharacterized density. Furthermore, our model, in combinat2023-01-01T00:00:00Z2023 Mar2026-04-08T13:25:28.903Z2025-02-19T04:46:18.133ZS-EPMC100554283699369910.1101/2023.03.22.533729