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Signal sequence–independent SRP-SR complex formation at the membrane suggests an alternative targeting pathway within the SRP cycle

Protein targeting by the signal recognition particle (SRP) and the bacterial SRP receptor FtsY requires a series of closely coordinated steps that monitor the presence of a substrate, the membrane, and a vacant translocon. Although the influence of substrate binding on FtsY-SRP complex formation is...

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Autores principales: Braig, David, Mircheva, Miryana, Sachelaru, Ilie, van der Sluis, Eli O., Sturm, Lukas, Beckmann, Roland, Koch, Hans-Georg
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3128533/
https://www.ncbi.nlm.nih.gov/pubmed/21551068
http://dx.doi.org/10.1091/mbc.E11-02-0152
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author Braig, David
Mircheva, Miryana
Sachelaru, Ilie
van der Sluis, Eli O.
Sturm, Lukas
Beckmann, Roland
Koch, Hans-Georg
author_facet Braig, David
Mircheva, Miryana
Sachelaru, Ilie
van der Sluis, Eli O.
Sturm, Lukas
Beckmann, Roland
Koch, Hans-Georg
author_sort Braig, David
collection PubMed
description Protein targeting by the signal recognition particle (SRP) and the bacterial SRP receptor FtsY requires a series of closely coordinated steps that monitor the presence of a substrate, the membrane, and a vacant translocon. Although the influence of substrate binding on FtsY-SRP complex formation is well documented, the contribution of the membrane is largely unknown. In the current study, we found that negatively charged phospholipids stimulate FtsY-SRP complex formation. Phospholipids act on a conserved positively charged amphipathic helix in FtsY and induce a conformational change that strongly enhances the FtsY-lipid interaction. This membrane-bound, signal sequence–independent FtsY-SRP complex is able to recruit RNCs to the membrane and to transfer them to the Sec translocon. Significantly, the same results were also observed with an artificial FtsY-SRP fusion protein, which was tethered to the membrane via a transmembrane domain. This indicates that substrate recognition by a soluble SRP is not essential for cotranslational targeting in Escherichia coli. Our findings reveal a remarkable flexibility of SRP-dependent protein targeting, as they indicate that substrate recognition can occur either in the cytosol via ribosome-bound SRP or at the membrane via a preassembled FtsY-SRP complex.
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spelling pubmed-31285332011-09-16 Signal sequence–independent SRP-SR complex formation at the membrane suggests an alternative targeting pathway within the SRP cycle Braig, David Mircheva, Miryana Sachelaru, Ilie van der Sluis, Eli O. Sturm, Lukas Beckmann, Roland Koch, Hans-Georg Mol Biol Cell Articles Protein targeting by the signal recognition particle (SRP) and the bacterial SRP receptor FtsY requires a series of closely coordinated steps that monitor the presence of a substrate, the membrane, and a vacant translocon. Although the influence of substrate binding on FtsY-SRP complex formation is well documented, the contribution of the membrane is largely unknown. In the current study, we found that negatively charged phospholipids stimulate FtsY-SRP complex formation. Phospholipids act on a conserved positively charged amphipathic helix in FtsY and induce a conformational change that strongly enhances the FtsY-lipid interaction. This membrane-bound, signal sequence–independent FtsY-SRP complex is able to recruit RNCs to the membrane and to transfer them to the Sec translocon. Significantly, the same results were also observed with an artificial FtsY-SRP fusion protein, which was tethered to the membrane via a transmembrane domain. This indicates that substrate recognition by a soluble SRP is not essential for cotranslational targeting in Escherichia coli. Our findings reveal a remarkable flexibility of SRP-dependent protein targeting, as they indicate that substrate recognition can occur either in the cytosol via ribosome-bound SRP or at the membrane via a preassembled FtsY-SRP complex. The American Society for Cell Biology 2011-07-01 /pmc/articles/PMC3128533/ /pubmed/21551068 http://dx.doi.org/10.1091/mbc.E11-02-0152 Text en © 2011 Braig et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0). “ASCB®,” “The American Society for Cell Biology®,” and “Molecular Biology of the Cell®” are registered trademarks of The American Society of Cell Biology.
spellingShingle Articles
Braig, David
Mircheva, Miryana
Sachelaru, Ilie
van der Sluis, Eli O.
Sturm, Lukas
Beckmann, Roland
Koch, Hans-Georg
Signal sequence–independent SRP-SR complex formation at the membrane suggests an alternative targeting pathway within the SRP cycle
title Signal sequence–independent SRP-SR complex formation at the membrane suggests an alternative targeting pathway within the SRP cycle
title_full Signal sequence–independent SRP-SR complex formation at the membrane suggests an alternative targeting pathway within the SRP cycle
title_fullStr Signal sequence–independent SRP-SR complex formation at the membrane suggests an alternative targeting pathway within the SRP cycle
title_full_unstemmed Signal sequence–independent SRP-SR complex formation at the membrane suggests an alternative targeting pathway within the SRP cycle
title_short Signal sequence–independent SRP-SR complex formation at the membrane suggests an alternative targeting pathway within the SRP cycle
title_sort signal sequence–independent srp-sr complex formation at the membrane suggests an alternative targeting pathway within the srp cycle
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3128533/
https://www.ncbi.nlm.nih.gov/pubmed/21551068
http://dx.doi.org/10.1091/mbc.E11-02-0152
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