Determinants of the assembly, integrity and maintenance of the endoplasmic reticulum‐peroxisome tether. (15th January 2019)

• Record Type: Journal Article
• Authors: Knoblach, Barbara; Rachubinski, Richard A.
• Is Part Of: Traffic. Volume 20:Number 3(2019)
• Page Start: 213
• Page End: 225
• Publication Date: 2019-01-15
• Subjects: endoplasmic reticulum -- Inp1p -- organelle tethering -- peroxisomes -- Pex3p; Biological transport -- Periodicals; 571.6
• DOI: 10.1111/tra.12635
• Languages: English
• ISSNs: 1398-9219

Abstract

Abstract : Organelle tethering and intercommunication are crucial for proper cell function. We previously described a tether between peroxisomes and the endoplasmic reticulum (ER) that acts in peroxisome population control in the yeast, Saccharomyces cerevisiae . Components of this tether are Pex3p, an integral membrane protein of both peroxisomes and the ER and Inp1p, a connector that links peroxisomes to the ER. Here, we report the analysis of random Inp1p mutants that enabled identification of regions in Inp1p required for the assembly and maintenance of the ER‐peroxisome tether. Interaction analysis between Inp1p mutants and known Inp1p‐binding proteins demonstrated that Pex3p and Inp1p do not constitute the sole components of the ER‐peroxisome tether. Deletion of these Inp1p interactors whose steady‐state localization is outside of ER‐peroxisome tethers affected peroxisome dynamics. Our findings are consistent with the presence of regulatory cues that act on ER‐peroxisome tethers and point to the existence of membrane contact sites between peroxisomes and organelles other than the ER. Abstract : Tethering between organelles is crucial for interorganellar communication and overall cell function. The yeast ER‐peroxisome tether contains Pex3p, a membrane protein of peroxisomes and the ER, and Inp1p, a connector linking peroxisomes to the ER. We defined regions in Inp1p required for tether assembly and maintenance, and showed that proteins that interact with Inp1p but localize primarily outside of ER‐peroxisome tethers affect peroxisome dynamics. Peroxisomes move on actin tracks, driven by the Myo2p motor that interacts through its cargo‐binding domain to its receptor on the peroxisomal membrane, Inp2p. Our findings suggest the presence of regulatory cues acting on ER‐peroxisome tethers and the existence of membrane contact sites between peroxisomes and organelles other than the ER.