Cargando…

Binding of the GTPase Sar1 to a Lipid Membrane Monolayer: Insertion and Orientation Studied by Infrared Reflection–Absorption Spectroscopy

Membrane-interacting proteins are polyphilic polymers that engage in dynamic protein–protein and protein–lipid interactions while undergoing changes in conformation, orientation and binding interfaces. Predicting the sites of interactions between such polypeptides and phospholipid membranes is still...

Descripción completa

Detalles Bibliográficos
Autores principales: Schwieger, Christian, Meister, Annette, Daum, Sebastian, Blume, Alfred, Bacia, Kirsten
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418733/
https://www.ncbi.nlm.nih.gov/pubmed/30965916
http://dx.doi.org/10.3390/polym9110612
_version_ 1783403799235264512
author Schwieger, Christian
Meister, Annette
Daum, Sebastian
Blume, Alfred
Bacia, Kirsten
author_facet Schwieger, Christian
Meister, Annette
Daum, Sebastian
Blume, Alfred
Bacia, Kirsten
author_sort Schwieger, Christian
collection PubMed
description Membrane-interacting proteins are polyphilic polymers that engage in dynamic protein–protein and protein–lipid interactions while undergoing changes in conformation, orientation and binding interfaces. Predicting the sites of interactions between such polypeptides and phospholipid membranes is still a challenge. One example is the small eukaryotic GTPase Sar1, which functions in phospholipid bilayer remodeling and vesicle formation as part of the multimeric coat protein complex (COPII). The membrane interaction of Sar1 is strongly dependent on its N-terminal 23 amino acids. By monolayer adsorption experiments and infrared reflection-absorption spectroscopy (IRRAS), we elucidate the role of lipids in inducing the amphipathicity of this N-terminal stretch, which inserts into the monolayer as an amphipathic helix (AH). The AH inserting angle is determined and is consistent with the philicities and spatial distribution of the amino acid monomers. Using an advanced method of IRRAS data evaluation, the orientation of Sar1 with respect to the lipid layer prior to the recruitment of further COPII proteins is determined. The result indicates that only a slight reorientation of the membrane-bound Sar1 is needed to allow coat assembly. The time-course of the IRRAS analysis corroborates a role of slow GTP hydrolysis in Sar1 desorption from the membrane.
format Online
Article
Text
id pubmed-6418733
institution National Center for Biotechnology Information
language English
publishDate 2017
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-64187332019-04-02 Binding of the GTPase Sar1 to a Lipid Membrane Monolayer: Insertion and Orientation Studied by Infrared Reflection–Absorption Spectroscopy Schwieger, Christian Meister, Annette Daum, Sebastian Blume, Alfred Bacia, Kirsten Polymers (Basel) Article Membrane-interacting proteins are polyphilic polymers that engage in dynamic protein–protein and protein–lipid interactions while undergoing changes in conformation, orientation and binding interfaces. Predicting the sites of interactions between such polypeptides and phospholipid membranes is still a challenge. One example is the small eukaryotic GTPase Sar1, which functions in phospholipid bilayer remodeling and vesicle formation as part of the multimeric coat protein complex (COPII). The membrane interaction of Sar1 is strongly dependent on its N-terminal 23 amino acids. By monolayer adsorption experiments and infrared reflection-absorption spectroscopy (IRRAS), we elucidate the role of lipids in inducing the amphipathicity of this N-terminal stretch, which inserts into the monolayer as an amphipathic helix (AH). The AH inserting angle is determined and is consistent with the philicities and spatial distribution of the amino acid monomers. Using an advanced method of IRRAS data evaluation, the orientation of Sar1 with respect to the lipid layer prior to the recruitment of further COPII proteins is determined. The result indicates that only a slight reorientation of the membrane-bound Sar1 is needed to allow coat assembly. The time-course of the IRRAS analysis corroborates a role of slow GTP hydrolysis in Sar1 desorption from the membrane. MDPI 2017-11-14 /pmc/articles/PMC6418733/ /pubmed/30965916 http://dx.doi.org/10.3390/polym9110612 Text en © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Schwieger, Christian
Meister, Annette
Daum, Sebastian
Blume, Alfred
Bacia, Kirsten
Binding of the GTPase Sar1 to a Lipid Membrane Monolayer: Insertion and Orientation Studied by Infrared Reflection–Absorption Spectroscopy
title Binding of the GTPase Sar1 to a Lipid Membrane Monolayer: Insertion and Orientation Studied by Infrared Reflection–Absorption Spectroscopy
title_full Binding of the GTPase Sar1 to a Lipid Membrane Monolayer: Insertion and Orientation Studied by Infrared Reflection–Absorption Spectroscopy
title_fullStr Binding of the GTPase Sar1 to a Lipid Membrane Monolayer: Insertion and Orientation Studied by Infrared Reflection–Absorption Spectroscopy
title_full_unstemmed Binding of the GTPase Sar1 to a Lipid Membrane Monolayer: Insertion and Orientation Studied by Infrared Reflection–Absorption Spectroscopy
title_short Binding of the GTPase Sar1 to a Lipid Membrane Monolayer: Insertion and Orientation Studied by Infrared Reflection–Absorption Spectroscopy
title_sort binding of the gtpase sar1 to a lipid membrane monolayer: insertion and orientation studied by infrared reflection–absorption spectroscopy
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418733/
https://www.ncbi.nlm.nih.gov/pubmed/30965916
http://dx.doi.org/10.3390/polym9110612
work_keys_str_mv AT schwiegerchristian bindingofthegtpasesar1toalipidmembranemonolayerinsertionandorientationstudiedbyinfraredreflectionabsorptionspectroscopy
AT meisterannette bindingofthegtpasesar1toalipidmembranemonolayerinsertionandorientationstudiedbyinfraredreflectionabsorptionspectroscopy
AT daumsebastian bindingofthegtpasesar1toalipidmembranemonolayerinsertionandorientationstudiedbyinfraredreflectionabsorptionspectroscopy
AT blumealfred bindingofthegtpasesar1toalipidmembranemonolayerinsertionandorientationstudiedbyinfraredreflectionabsorptionspectroscopy
AT baciakirsten bindingofthegtpasesar1toalipidmembranemonolayerinsertionandorientationstudiedbyinfraredreflectionabsorptionspectroscopy