BioDesign 2023; 11(2): 21-27
Published online June 30, 2023
https://doi.org/10.34184/kssb.2023.11.2.21
© Korean Society for Structural Biology
Yeongjin Baek1, Jinwook Lee1, Dukwon Lee1, Yongbin Xu2,3,4,* and Nam-Chul Ha1,2,*
1Department of Agricultural Biotechnology, Research Institute of Agriculture and Life Sciences, CALS, Seoul National University, Seoul 08826, Republic of Korea
2Center for Food and Bioconvergence, Seoul National University, Seoul 08826, Republic of Korea
3Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, Liaoning, China
4Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, Dalian 116600, Liaoning, China
Correspondence to: *yongbinxu@dlnu.edu.cn, hanc210@snu.ac.kr
The HlyBD-TolC complex, belonging to the type I secretion system (T1SS), is found in many pathogenic Gram-negative bacteria. This complex comprises three components: the ABC-type inner membrane transporter HlyB, the periplasmic adaptor HlyD, and the outer membrane channel TolC. Recent crystal and cryo-EM structures have shed light on the stoichiometry of the HlyB hexamer and HlyD hexamer in the functional complex. In this study, we performed a modeling study using the AI-based structure prediction program Alphafold-multimer to gain a deeper understanding of the assembly of the T1SS system. The program predicted a funnel-like hexameric model of the HlyD, which was stable in a molecular dynamics simulation, and the HlyD hexamer would intermesh with the TolC trimer in a cogwheel structure. Combining the modeled and docked structures, we built an assembly model of HlyBD-TolC, showing a central channel spanning the complex. These observations suggest a mechanism reminiscent of the DNA helicase.