Nanodomain remorin oligomerization status fine-tunes formin activity in actin nucleation

• Main Author: Sim, Jia Xin
• Other Authors: Miao Yansong
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Science::Biological sciences
• Online Access: https://hdl.handle.net/10356/157112
• Institution: Nanyang Technological University

Nanodomains are nanometer scale subcompartments in dynamic plasma membrane, enriched in specific lipids and protein components that manage cellular processes. A well-characterized marker for lipid nanodomain, remorin protein has been identified in involving nanodomain clustering. The assembly of nanodomain remorin and actin nucleating formin protein at cell surface act functional roles in promoting actin cytoskeleton polymerization during plant innate response. The biochemical activity of remorin is mostly controlled by N-terminal intrinsically disordered region (IDR), coiled-coil (CC) domain, and C-terminal membrane anchoring region, but less is known about the specificity driven by protein multivalency. Herein, we design multivalent recombinant remorin proteins with different CC oligomerization status and determine the underlying association of remorin oligomerization with formin nucleating protein. Due to multivalent cooperativity, remorin oligomers show self-assembly upon binding on membrane surface. In bulk pyrene actin assay, formin positively regulates actin polymerization, either directly or as mediated by remorin oligomers. This indicates that the degree of remorin oligomerization influences formin to nucleate actin. Furthermore, remorin with trimeric coiled-coil structure is likely to facilitate membrane anchoring and formin-dependent actin polymerization, while a potent inhibition of actin nucleation is detected when guided by higher-order remorin oligomers. Such nanodomain remorin mediated regulation of formin is expected to fine-tune immune signals transduction in plant host.