Mechanism and cellular function of direct membrane binding by the ESCRT and ERES- associated Ca2+- sensor ALG-2

• 成果类型: Article
• 署名作者: Shukla, Sankalp; Chen, Wei; Rao, Shanlin; Yang, Serim; Ou, Chenxi; Larsen, Kevin P.; Hummer, Gerhard; Hanson, Phyllis I.; Hurley, James H.
• 署名单位: University of California System; University of California Berkeley; University of California System; University of California Berkeley; University of Michigan System; University of Michigan; Max Planck Society; Goethe University Frankfurt; University of California System; University of California Berkeley
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8888
• DOI: 10.1073/pnas.2318046121
• 发表日期: 2024-02-27
• 关键词: reticulum exit sites; particle mesh ewald; structural basis; protein alg-2; sec31a; RECOGNITION; domain; electrostatics; insights; complex

摘要

Apoptosis linked Gene - 2 (ALG-2) is a multifunctional intracellular Ca2+ sensor and the archetypal member of the penta-EF hand protein family. ALG-2 functions in the repair of damage to both the plasma and lysosome membranes and in COPII- dependent budding at endoplasmic reticulum exit sites (ERES). In the presence of Ca2+, ALG-2 binds to ESCRT-I and ALIX in membrane repair and to SEC31A at ERES. ALG-2 also binds directly to acidic membranes in the presence of Ca2+ by a combination of electrostatic and hydrophobic interactions. By combining giant unilamellar vesicle - based experiments and molecular dynamics simulations, we show that charge- reversed mutants of ALG-2 at these locations disrupt membrane recruitment. ALG-2 membrane binding mutants have reduced or abrogated ERES localization in response to Thapsigargin- induced Ca2+ release but still localize to lysosomes following lysosomal Ca2+ release. In vitro reconstitution shows that the ALG-2 membrane- binding defect can be rescued by binding to ESCRT-I. These data thus reveal the nature of direct Ca2+- dependent membrane binding and its interplay with Ca2+- dependent protein binding in the cellular functions of ALG-2.