Non-vesicular glycerolipids transport in plant cells

Phylogenetic and Structural Analyses of VPS13 Proteins in Archaeplastida Reveal Their Complex Evolutionary History in Viridiplantae

“…The origin of VPS13X is puzzling as its sequence and domain organization is highly divergent compared to other paralogs. In agreement with this, VPS13X was only recently identified by remote homology analyses ( Levine, 2022 ) and not in previous studies using BLASTP searches ( Velayos-Baeza et al, 2004 ; Michaud et al, 2017 ; Leterme and Michaud, 2022 ). VPS13X is composed of nine RBG domains, having the smallest number of repeats in currently characterized VPS13s, and is the only group of VPS13 in which a C-term PH domain is absent, amphipathic α-helices are found instead ( Levine, 2022 ).…”

“…This family emerged in Embryophytes after the split with Charophytes and more than 100 genes are currently found in genomes of higher plants, highlighting the extremely rapid expansion of this family ( Edstam et al, 2011 ). Noteworthy, the number of other LTP homologous families, such as the StARTs (steroidogenic acute regulatory protein-related lipid transfer) or the ORPs (Oxysterol-binding protein related proteins), is often higher in plants compared to yeast or animals ( Leterme and Michaud, 2022 ). This is likely linked to the emergence of new cell functions and structures such as chloroplasts, plasmodesmata, or complex cell walls.…”

Membrane contacts with the endoplasmic reticulum modulate plastid morphology and behaviour

“…Since demonstration of interactivity between BnCLIP1-eGFP punctae and ER was carried out only through transient overexpression assays in agroinfiltrated tobacco leaves, a clear estimation of its lipase activity in tobacco has been missing ( Tan et al., 2011 ). Nevertheless, subsequent publications have treated BnCLIP1 as a general TAG lipase and speculated about its role as a membrane contact site (MCS) promoting protein ( Block and Jouhet, 2015 ; Mueller-Schuessele and Michaud, 2018 ; Michaud and Jouhet, 2019 ; Li et al., 2020 ; Leterme and Michaud, 2022 ). Whether the Arabidopsis lines overexpressing BnCLIP1 generated by us have an overall increase in lipase activity has not been investigated.…”

“…An important tool for investigating plastid-ER relationship including the formation of MCS has become available in the form of a putative Brassica napus chloroplast-localized lipase fused to eGFP (BnCLIP1-eGFP; Tan et al., 2011 ). Despite missing unequivocal support for the purported lipase activity of BnCLIP1, several publications have presented it as a general TAG lipase and speculated about its functions ( Block and Jouhet, 2015 ; Mueller-Schuessele and Michaud, 2018 ; Michaud and Jouhet, 2019 ; Li et al., 2020 ; Leterme and Michaud, 2022 ).Transient expression of BnCLIP1-eGFP in tobacco leaf tissue revealed a clear punctate localization on the plastid envelope. Observations of ER membranes in proximity to the BnCLIP1-eGFP punctae strongly suggested it as a potential candidate protein for MCS formation ( Tan et al., 2011 ).…”

“…Here, based on its demonstrated interactivity with the ER ( Tan et al., 2011 ) and its citation as a MCS marker ( Block and Jouhet, 2015 ; Michaud and Jouhet, 2019 ; Leterme and Michaud, 2022 ), we generated stable transgenic lines of Arabidopsis thaliana expressing BnCLIP1-eGFP. As shown here, we have used this important fiducial marker for investigating plastid-ER interactions.…”