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Unconventional vesicle transport driven by formin-actin-myosin working system during pollen germination
Tonghui Li1, Chang Liu1, Tongtong Shen1
1Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
Science Advances
|July 10, 2026
Summary
Myosin XI (Myo11C) proteins facilitate directional transport of secretory vesicles crucial for pollen germination. They interact with formin-nucleated actin filaments and vesicle-associated SEC5B to drive vesicle movement.
Area of Science:
- Plant cell biology
- Molecular plant physiology
- Cytoskeletal dynamics
Background:
- Directional transport of massive secretory vesicles to the germination site is essential for pollen germination.
- The precise molecular mechanisms governing this process remain largely unelucidated.
Purpose of the Study:
- To investigate the molecular mechanism of directional secretory vesicle transport during pollen germination.
- To identify the roles of Myosin XI (Myo11C) proteins in this process.
Main Methods:
- Analysis of *myo11c1 myo11c2* double mutants to assess functional redundancy.
- Colocalization studies of Myo11C1 with secretory vesicles and actin filaments.
- Simulated modeling and truncation mutation analyses to determine protein interactions.
- Identification of critical residues for Myo11C1 binding to F-actin and SEC5B.
Main Results:
- Myosin XI (Myo11C) proteins, Myo11C1 and Myo11C2, exhibit functional redundancy in pollen germination.
- Myo11C1 colocalizes with AtFH5-nucleated actin filaments and secretory vesicles (AtFH5-SVs).
- Myo11C binds actin filaments, moves towards the plus-end, and subsequently interacts with AtFH5-SVs to promote their aggregation.
- Specific residues (E447, R1377, R1452) are identified as critical for Myo11C1's interactions with F-actin and SEC5B.
Conclusions:
- The formin-actin-myosin system orchestrates directional transport of massive secretory vesicles during pollen germination.
- Myosin XI (Myo11C) plays a pivotal role in linking actin dynamics to vesicle movement and aggregation.
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