A Peptoid Delivers CoQ-derivative to Plant Mitochondria via Endocytosis

Abstract

Controlled delivery of molecules interfering specifically with target activities in a cell of interest can be a powerful tool for experimental manipulation, because it can be administered at a defined time point and does not require genetic transformation, which in some systems is difficult and time consuming. Peptides as versatile tools that can be tailored for binding numerous binding partners, are of special interest. However, their passage through membranes, their intracellular targeting, and their sensitivity to proteases is limiting. The use of peptoids, where cationic amino-acid side chains are linked to nitrogen (rather than to carbon) of the peptide bond, can circumvent these limitations, because they are not cleavable by proteases. In the current work, we provide a proof-of-concept that such Trojan Peptoids, the plant PeptoQ, can be used to target a functional cargo (i.e. a rhodamine-labelled peptoid and a coenzyme Q10 derivative) into mitochondria of tobacco BY-2 cells as experimental model. We show that the uptake is specific for mitochondria, rapid, dose-dependent, and requires clathrin-mediated endocytosis, as well as actin filaments, while microtubules seem to be dispensable. Viability of the treated cells is not affected, and they show better survival under salt stress, a condition that perturbs oxidative homeostasis in mitochondria. In congruence with improved homeostasis, we observe that the salt induced accumulation of superoxide is mitigated and even inverted by pretreatment with PeptoQ. Using double labelling with appropriate fluorescent markers, we show that targeting of this Trojan Peptoid to the mitochondria is not based on a passage through the plasma membrane (as thought hitherto), but on import via endocytotic vesicles and subsequent accumulation in the mitochondrial intermembrane space, from where it can enter the matrix, e.g. when the permeability of the inner membrane is increased under salt stress.

The jasmonate biosynthesis Gene OsOPR7 can mitigate salinity induced mitochondrial oxidative stress

“…In our previous work, we have shown that Plant PeptoQ, a cell penetrating peptoid with a mitochondria-targeting motif and endowed with a semiquinone moiety mimetic of coenzyme Q10, was rapidly and efficiently targeted to the mitochondria of walled tobacco BY-2 cells [35], which conferred improved resilience to salt stress. Subsequently, we could show that this mitigation was caused by a modulation of retrograde signalling culminating in higher expression of the mitochondrial superoxide dismutase [36].…”

A mitochondria-targeted coenzyme Q peptoid induces superoxide dismutase and alleviates salinity stress in plant cells

“…In our previous work 36 , we have developed a construct, plant PeptoQ, composed of a peptoid mediating mitochondrial import, and a functional cargo that mimics coenzyme Q10. We were able to show that this construct was efficiently and specifically accumulating in mitochondria of walled tobacco BY-2 cells and improved their resilience against salinity stress.…”

“…In our previous work, we have shown that plant PeptoQ, a cell penetrating peptoid with a mitochondriatargeting motif and endowed with a semiquinone mimetic of coenzyme Q10 (Fig. 1), was rapidly and efficiently targeted to the mitochondria of walled tobacco BY-2 cells 36 and conferred improved resilience to salt stress. Hence, in our current study, we analyse the mode of action behind this mitigation.…”

Mitochondrion-Targeting Peptides and Peptidomimetics: Recent Progress and Design Principles

“…In another work reported by the same group, TPP was used as a side chain with alternating N lys residues, and surprisingly, this hexameric peptoid did not appear to localize to the mitochondria; instead, it was trapped in the endosomes, which might be attributed to their excessive positive charges. Incorporating guanidinine side chains appeared to be more advantageous than N lys for mitochondrial localization, as demonstrated by Asfaw and co-workers . In this work, they delivered the coenzyme Q10 (CoQ10) derivative named Pepto Q into plant mitochondria by using a polyguanidine peptoid as a delivery apparatus (compound 23 ) .…”

“…Incorporating guanidinine side chains appeared to be more advantageous than N lys for mitochondrial localization, as demonstrated by Asfaw and co-workers . In this work, they delivered the coenzyme Q10 (CoQ10) derivative named Pepto Q into plant mitochondria by using a polyguanidine peptoid as a delivery apparatus (compound 23 ) . Like its peptide counterpart, polyguanidine peptoid also enables the cellular transport of conjugated molecules. − It was proposed that Pepto Q was internalized via clathrin-dependent endocytosis, accumulated first in endosomes and then in the ER, and then transported to the intermembrane space of the mitochondria in two steps.…”