%0 Journal Article
%T Structural insights into the assembly pathway of the Helicobacter pylori CagT4SS outer membrane core complex.
%A Mok CY
%A Chu HY
%A Lam WWL
%A Au SWN
%J Structure
%V 0
%N 0
%D 2024 Jul 10
%M 39032488
%F 5.871
%R 10.1016/j.str.2024.06.019
%X Cag type IV secretion system (CagT4SS) translocates oncoprotein cytotoxin-associated gene A (CagA) into host cells and plays a key role in the pathogenesis of Helicobacter pylori. The structure of the outer membrane core complex (OMCC) in CagT4SS consists of CagX, CagY, CagM, CagT, and Cag3 in a stoichiometric ratio of 1:1:2:2:5 with 14-fold symmetry. However, the assembly pathway of OMCC remains elusive. Here, we report the crystal structures of CagT and Cag3-CagT complex, and the structural dynamics of Cag3 and CagT using hydrogen deuterium exchange-mass spectrometry (HDX-MS). The interwoven interaction of Cag3 and CagT involves conformational changes of CagT and β strand swapping. In conjunction with biochemical and biophysical assays, we further demonstrate the different oligomerization states of Cag3 and Cag3-CagT complex. Additionally, the association with CagM requires the pre-formation of Cag3-CagT complex. These results demonstrate the generation of different intermediate sub-assemblies and their structural flexibility, potentially representing different building blocks for OMCC assembly.