November 1, 2023
The Zhang Lab recently published Cryo-EM structures in the Journal of Cell Biology that elucidate how mastigonemes – thread-like structures adorning the flagella of protists – assemble to respond toenvironmental signal changes. Led by Yue Wang, Jun Yang, Fangheng Hu, and Yucheng Yang, the work explores the atomic details of the mastigoneme structure and its mysterious roles in sensing environmental signals and regulation of flagellar motility.
Mastigonemes are believed to play important roles in external signal sensing by protists. In the model organism Chlamydomonas reinhardtii, these filamentous structures are closely associated with the transient receptor potential (TRP) channel protein PKD2, suggesting a role in the control of flagellar motility in response to environmental cues.The study presents structures of mastigoneme at up to 3.4-Å resolution determined by a combination of cryo-electron tomography and single-particle cryo-electron microscopy. These high-resolution structures reveal an intricate organization of the major unit of this filament, MST1. MST1 subunits assemble periodically to form a centrosymmetric, non-polar filament, highlighting the precision of their architecture. Intriguingly, the structures highlight numerous clustered disulfide bonds arrangedin a ladder-like spiral configuration. This remarkable feature underlines the mastigoneme’s potentialroles in its resilience to environmental changes.
The authors found that while defects in the mastigoneme structure did not significantly impact the general swimming attributes of Chlamydomonas reinhardtii, they did affect specific swimming properties, particularly under varying environmental conditions such as redox changes and increased viscosity. This points to the potential role of mastigonemes in flagellar motility and their involvement in diverse environmental responses.
The full details and figures of the study can be found on JCB.