Eeyarestatin Compounds Selectively Enhance Sec61-Mediated Ca2+ Leakage from the Endoplasmic Reticulum

• Published in: Cell chemical biology Vol. 26; no. 4; pp. 571 - 583.e6
• Main Authors: Gamayun, Igor, O'Keefe, Sarah, Pick, Tillman, Klein, Marie-Christine, Nguyen, Duy, McKibbin, Craig, Piacenti, Michela, Williams, Helen M., Flitsch, Sabine L., Whitehead, Roger C., Swanton, Eileithyia, Helms, Volkhard, High, Stephen, Zimmermann, Richard, Cavalié, Adolfo
• Format: Journal Article
• Language: English
• Published: Cell Press 18.04.2019
• ISSN: 2451-9456; 2451-9456
• DOI: 10.1016/j.chembiol.2019.01.010

Eeyarestatin 1 (ES1) inhibits p97-dependent protein degradation, Sec61-dependent protein translocation into the endoplasmic reticulum (ER), and vesicular transport within the endomembrane system. Here, we show that ES1 impairs Ca 2+ homeostasis by enhancing the Ca 2+ leakage from mammalian ER. A comparison of various ES1 analogs suggested that the 5-nitrofuran (5-NF) ring of ES1 is crucial for this effect. Accordingly, the analog ES24, which conserves the 5-NF domain of ES1, selectively inhibited protein translocation into the ER, displayed the highest potency on ER Ca 2+ leakage of ES1 analogs studied and induced Ca 2+ -dependent cell death. Using small interfering RNA-mediated knockdown of Sec61α, we identified Sec61 complexes as the targets that mediate the gain of Ca 2+ leakage induced by ES1 and ES24. By interacting with the lateral gate of Sec61α, ES1 and ES24 likely capture Sec61 complexes in a Ca 2+ -permeable, open state, in which Sec61 complexes allow Ca 2+ leakage but are translocation incompetent. • ES1, ES2, and ES24 deplete Ca 2+ in ER • ESR35 and ES47 do not affect cellular Ca 2+ homeostasis • The most potent eeyarestatin, ES24, comprises only the 5-nitrofuran domain • ES1 and ES24 target Sec61 complexes in ER Gamayun et al. discovered that eeyarestatins (ESs) interfere with closing mechanisms of Sec61 complexes of the ER and, as a “foot in the door,” stabilize Sec61 complexes in a Ca 2+ -permeable, open state. Specifically, ES24 enhances strongly the Sec61-mediated Ca 2+ leakage from ER and induces Ca 2+ -dependent cell death.