Amanda Koenig

Date: March 5, 2024

Time: 12:00 pm

In-person location: 168 PLB

Zoom: https://bit.ly/prltuesnoon
Meeting ID: 957 9659 6975
Passcode: 420205

Speaker: Amanda Koenig

Lab: Hu lab

Title: The mechanisms of actin-dependent peroxisome motility during biotic stress and photorespiration

Abstract: Peroxisomes are highly dynamic organelles in eukaryotic cells, essential in lipid metabolism and ROS homeostasis, among other processes. In plant cells, they also operate in close coordination with other organelles, such as chloroplasts and mitochondria, to carry out critical energy related metabolism, like photorespiration. Proximity for their collaborative functions necessitates subcellular translocation and redistribution of organelles in response to internal and external cues. In plants, Myosin XI motors are the primary drivers for organelle motility along actin filaments, however the molecular mechanisms which dictate specificity and the signals and stimuli that initiate organelle movement remain elusive. We have uncovered several Myosin XI-K interactors that contribute to peroxisome motility, likely as adaptors or receptors for peroxisome-specific myosin recruitment. Using spinning disk confocal microscopy, we captured peroxisomes in high-speed intervals to evaluate peroxisome velocity and patterns of motion in Arabidopsis T-DNA mutants of corresponding genes. Our findings support the notion that PEX14, a peroxisome biogenesis factor involved in protein import, and TSA1, a protein previously known to be involved in ER body formation, may serve as the interface of peroxisomes and myosins to regulate plant peroxisome motility. To address the mechanisms by which peroxisomes are involved in stress response, we analyzed peroxisome dynamics in plants under bacterial (P. syringae) infection and in photorespiration-compromised mutants.  Finally, because multi-organellar dynamics are required for many biological processes, including immunity and photorespiration, we imaged fluorescently-tagged peroxisomes, mitochondria, chloroplasts, and actin filaments simultaneously in live cells to evaluate peroxisome motility in the context of its interaction with the other energy organelles. Our data suggest that peroxisome mobility may play a critical role in plant biotic stress response and photorespiration. The discovery of novel elements for the fundamental mechanics of peroxisome movement during stress and metabolism has vast potential to support plant health and resilience.

This work was supported by funding from The National Science Foundation to Jianping Hu (MCB 2148206) & Bo Liu (MCB 2148207).