Effect of cardiolipin on aquaporin Z: a cryo-EM study

Aquaporins are a family of transmembrane channel proteins responsible for osmoregulation in biological systems. Despite their important physiological role, modulators of aquaporin activity are still not available. An anionic lipid, cardiolipin, was found to stabilize aquaporin Z (AqpZ), an aquaporin...

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Main Author: Leo, Zhenn Yi
Other Authors: Jaume Torres
Format: Final Year Project (FYP)
Language:English
Published: Nanyang Technological University 2023
Subjects:
Online Access:https://hdl.handle.net/10356/166518
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author Leo, Zhenn Yi
author2 Jaume Torres
author_facet Jaume Torres
Leo, Zhenn Yi
author_sort Leo, Zhenn Yi
collection NTU
description Aquaporins are a family of transmembrane channel proteins responsible for osmoregulation in biological systems. Despite their important physiological role, modulators of aquaporin activity are still not available. An anionic lipid, cardiolipin, was found to stabilize aquaporin Z (AqpZ), an aquaporin found in E. coli, and increase its water permeability. This paper focuses on the cryo-EM structural determination of AqpZ in nanodiscs, with and without added E. coli cardiolipin, to understand the mechanism by which cardiolipin stabilizes and increases the activity of AqpZ. This understanding could facilitate the development of drugs capable of modulating aquaporin activity. Single particle analysis (SPA) of cryo-EM data yielded a 6.3 Å structure of AqpZ in lipid environment. Comparison of this structure with the X-ray crystal structure of AqpZ in octyl glucoside detergent revealed minor structural differences. The resolution of the structure obtained was likely limited due to the high symmetry of the tetrameric molecule resulting in poor alignment of particles during SPA. A fusion protein construct of maltose-binding protein (MBP) and AqpZ was designed to introduce asymmetry to the molecule. The purified protein was shown to tetramerize in mild detergents, indicating that MBP-AqpZ is a suitable candidate for reconstitution into nanodiscs for cryo-EM data collection.
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spelling ntu-10356/1665182023-05-08T15:33:57Z Effect of cardiolipin on aquaporin Z: a cryo-EM study Leo, Zhenn Yi Jaume Torres School of Biological Sciences JTorres@ntu.edu.sg Science::Biological sciences::Molecular biology Aquaporins are a family of transmembrane channel proteins responsible for osmoregulation in biological systems. Despite their important physiological role, modulators of aquaporin activity are still not available. An anionic lipid, cardiolipin, was found to stabilize aquaporin Z (AqpZ), an aquaporin found in E. coli, and increase its water permeability. This paper focuses on the cryo-EM structural determination of AqpZ in nanodiscs, with and without added E. coli cardiolipin, to understand the mechanism by which cardiolipin stabilizes and increases the activity of AqpZ. This understanding could facilitate the development of drugs capable of modulating aquaporin activity. Single particle analysis (SPA) of cryo-EM data yielded a 6.3 Å structure of AqpZ in lipid environment. Comparison of this structure with the X-ray crystal structure of AqpZ in octyl glucoside detergent revealed minor structural differences. The resolution of the structure obtained was likely limited due to the high symmetry of the tetrameric molecule resulting in poor alignment of particles during SPA. A fusion protein construct of maltose-binding protein (MBP) and AqpZ was designed to introduce asymmetry to the molecule. The purified protein was shown to tetramerize in mild detergents, indicating that MBP-AqpZ is a suitable candidate for reconstitution into nanodiscs for cryo-EM data collection. Bachelor of Science in Biological Sciences 2023-05-03T08:30:27Z 2023-05-03T08:30:27Z 2023 Final Year Project (FYP) Leo, Z. Y. (2023). Effect of cardiolipin on aquaporin Z: a cryo-EM study. Final Year Project (FYP), Nanyang Technological University, Singapore. https://hdl.handle.net/10356/166518 https://hdl.handle.net/10356/166518 en application/pdf Nanyang Technological University
spellingShingle Science::Biological sciences::Molecular biology
Leo, Zhenn Yi
Effect of cardiolipin on aquaporin Z: a cryo-EM study
title Effect of cardiolipin on aquaporin Z: a cryo-EM study
title_full Effect of cardiolipin on aquaporin Z: a cryo-EM study
title_fullStr Effect of cardiolipin on aquaporin Z: a cryo-EM study
title_full_unstemmed Effect of cardiolipin on aquaporin Z: a cryo-EM study
title_short Effect of cardiolipin on aquaporin Z: a cryo-EM study
title_sort effect of cardiolipin on aquaporin z a cryo em study
topic Science::Biological sciences::Molecular biology
url https://hdl.handle.net/10356/166518
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