In Vivo Quantification of Peroxisome Tethering to Chloroplasts in Tobacco Epidermal Cells Using Optical Tweezers

Abstract

Peroxisomes are highly motile organelles that display a range of motions within a short time frame. In static snapshots, they can be juxtaposed to chloroplasts, which has led to the hypothesis that they are physically interacting. Here, using optical tweezers, we tested the dynamic physical interaction in vivo. Using near-infrared optical tweezers combined with TIRF microscopy, we were able to trap peroxisomes and approximate the forces involved in chloroplast association in vivo in tobacco (Nicotiana tabacum) and observed weaker tethering to additional unknown structures within the cell. We show that chloroplasts and peroxisomes are physically tethered through peroxules, a poorly described structure in plant cells. We suggest that peroxules have a novel role in maintaining peroxisome-organelle interactions in the dynamic environment. This could be important for fatty acid mobilization and photorespiration through the interaction with oil bodies and chloroplasts, highlighting a fundamentally important role for organelle interactions for essential biochemistry and physiological processes.

Peroxisomes Extend Peroxules in a Fast Response to Stress via a Reactive Oxygen Species-Mediated Induction of the Peroxin PEX11a

“…These findings indicate that PEX11a is an important component of rapid ROS-mediated stress perception, with peroxules possibly being involved in regulating ROS accumulation to protect cells against oxidative stress. Peroxules have been reported to be associated with chloroplasts (Sinclair et al, 2009;Oikawa et al, 2015;Gao et al, 2016) and mitochondria , suggesting that they may contribute to the regulation of the excess H 2 O 2 produced in these organelles and may also favor interorganelle communication and transport. Peroxisomes contain enzymatic and nonenzymatic defense mechanisms to deal with different types of ROS such as O 2 .2 and H 2 O 2 .…”

“…After using optical tweezers to investigate peroxule functionality, Gao et al (2016) have suggested that peroxules play a role in establishing and maintaining connections and communication between organelles in the intracellular environment, particularly with those that have different motilities or are spatially separated. However, we believe that the functionality of these extensions could be also specifically related to the ROS metabolism.…”

Molecular Mechanisms and Physiological Significance of Organelle Interactions and Cooperation

“…This is quite different to optical tweezers which uses submicron precision to specifically "pull" rather than "push" an organelle. Both approaches have been used to establish physical connections between peroxisomes and chloroplasts (Oikawa et al, 2015;Gao et al, 2016).…”

“…More recently, Gao et al (2016) developed a quantifiable platform for using optical tweezers to measure organelle interactions in intact cells, more specifically the interaction between peroxisomes and chloroplasts. Here, using an automated platform to trap a peroxisome, users moved it a set distance at a set speed, and then monitored and quantified the effects on the organelle during this process; was it trapped?…”

Peroxisome Function, Biogenesis, and Dynamics in Plants

“…Peroxules can mediate interorganellar contacts, such as among peroxisomes and ER (Sinclair et al, 2009), oil bodies (Thazar-Poulot et al, 2015), mitochondria (Jaipargas et al, 2016), and chloroplasts (Gao et al, 2016). Moreover, peroxules can respond to environmental signals.…”