Communication between organelles gives cells a breath of fresh air
By Professor Maya Schuldiner, tenured associate professor at the Department of Molecular Genetics at the Weizmann Institute of Science, Israel
The endoplasmic reticulum (ER) forms an interconnected network of tubules and has several crucial roles in cells. These include the folding and maturation of proteins, the formation of lipids (fats), the orchestrating of biological activities and the trafficking of small solutes and other compounds necessary for cellular processes. To perform its functions, the ER must communicate with all other organelles; the tiny cellular structures that perform specific functions within a cell.
One example of this required communication is where many compounds have their precursors formed in the ER and then transferred to another organelle. One such metabolite is Coenzyme Q (CoQ). CoQ is a membrane-embedded lipid that is required for cellular respiration in mitochondria – this is the process by which the sugars that we eat are turned into usable energy in the cell. The synthesis of CoQ relies on a protein complex known as the CoQ synthome, located inside mitochondria. However, the building blocks for CoQ are first formed on the ER membrane. So how do ER-bound building blocks find their way to mitochondria?
One way that chemicals like CoQ can move between organelles is through contact sites. Contact sites are areas where two organelles are held close together by tethers (like a molecular zipper). Our research is conducted in a simple cell that resembles human cells very much, and this is the yeast cell. In yeast, the ER forms a contact site with mitochondria using several tethers, one of which is termed the ER-mitochondrial encounter structure (ERMES).
Our research showed that ERMES helps position the complex responsible for making CoQ in proximity to ER-mitochondria contact sites. Using ways to track newly synthesized CoQ, we also showed that yeast cells lacking ERMES complex are less efficient in CoQ production. This may explain why mutants in ERMES have a respiration defect, a phenomenon that has puzzled scientists in the past. Our findings provide insight into the involvement of an ER-mitochondria tether in the regulation of CoQ biogenesis and more broadly into organelle communication and collaboration.
The Endoplasmic Reticulum-Mitochondria Encounter Structure Complex Coordinates Coenzyme Q Biosynthesis
Michal Eisenberg-Bord, Hui S. Tsui, Diana Antunes, Lucía Fernández-del-Río, Michelle C. Bradley, Cory D. Dunn, Theresa P. T. Nguyen, Doron Rapaport, Catherine F. Clarke, Maya Schuldiner
Featured image credit: 201601_Endoplasmic_reticulum.png by DataBase Center for Life Science (DBCLS) is licensed under CC BY 4.0.
Professor Maya Schuldiner is a tenured associate professor at the Department of Molecular Genetics at the Weizmann Institute of Science, Israel, and the 2017 recipient of the EMBO Gold Medal Award.