Structural insights into the molecular mechanism of phytoplasma immunodominant membrane protein.
Chang Yi Liu, Han Pin Cheng, Chan Pin Lin, Yi Ting Liao, Tzu Ping Ko, Shin Jen Lin, Shih Shun Lin, Hao Ching Wang
Author Information
Chang Yi Liu: The PhD Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University and Academia Sinica, Taipei, Taiwan. ORCID
Han Pin Cheng: Institute of Biotechnology, National Taiwan University, Taipei, Taiwan.
Chan Pin Lin: Institute of Biotechnology, National Taiwan University, Taipei, Taiwan.
Yi Ting Liao: Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan. ORCID
Tzu Ping Ko: Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan. ORCID
Shin Jen Lin: International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan.
Shih Shun Lin: Institute of Biotechnology, National Taiwan University, Taipei, Taiwan.
Hao Ching Wang: The PhD Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University and Academia Sinica, Taipei, Taiwan. ORCID
Immunodominant membrane protein (IMP) is a prevalent membrane protein in phytoplasma and has been confirmed to be an F-actin-binding protein. However, the intricate molecular mechanisms that govern the function of IMP require further elucidation. In this study, the X-ray crystallographic structure of IMP was determined and insights into its interaction with plant actin are provided. A comparative analysis with other proteins demonstrates that IMP shares structural homology with talin rod domain-containing protein 1 (TLNRD1), which also functions as an F-actin-binding protein. Subsequent molecular-docking studies of IMP and F-actin reveal that they possess complementary surfaces, suggesting a stable interaction. The low potential energy and high confidence score of the IMP-F-actin binding model indicate stable binding. Additionally, by employing immunoprecipitation and mass spectrometry, it was discovered that IMP serves as an interaction partner for the phytoplasmal effector causing phyllody 1 (PHYL1). It was then shown that both IMP and PHYL1 are highly expressed in the S2 stage of peanut witches' broom phytoplasma-infected Catharanthus roseus. The association between IMP and PHYL1 is substantiated through in vivo immunoprecipitation, an in vitro cross-linking assay and molecular-docking analysis. Collectively, these findings expand the current understanding of IMP interactions and enhance the comprehension of the interaction of IMP with plant F-actin. They also unveil a novel interaction pathway that may influence phytoplasma pathogenicity and host plant responses related to PHYL1. This discovery could pave the way for the development of new strategies to overcome phytoplasma-related plant diseases.
