Actinorhodopsin: an efficient and robust light-driven proton pump for bionanotechnological applications
Abstract Actinorhodopsins are encoded by a distinct group of microbial rhodopsin (MR) genes predominant in non-marine actinobacteria. Despite their role in the global energy cycle and potential for bionanotechnological applications, our understanding of actinorhodopsin proteins is limited. Here, we...
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Nature Portfolio
2025-02-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-025-88055-8 |
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| author | Nooraldeen Ayoub Nadia Djabeur Daniel Harder Jean-Marc Jeckelmann Zöhre Ucurum Stephan Hirschi Dimitrios Fotiadis |
| author_facet | Nooraldeen Ayoub Nadia Djabeur Daniel Harder Jean-Marc Jeckelmann Zöhre Ucurum Stephan Hirschi Dimitrios Fotiadis |
| author_sort | Nooraldeen Ayoub |
| collection | DOAJ |
| description | Abstract Actinorhodopsins are encoded by a distinct group of microbial rhodopsin (MR) genes predominant in non-marine actinobacteria. Despite their role in the global energy cycle and potential for bionanotechnological applications, our understanding of actinorhodopsin proteins is limited. Here, we characterized the actinorhodopsin RlActR from the freshwater actinobacterium Rhodoluna lacicola, which conserves amino acid residues critical for light-driven proton pumping found in MRs. RlActR was efficiently overexpressed in Escherichia coli in milligram amounts and isolated with high purity and homogeneity. The purified RlActR absorbed green light and its primary proton acceptor exhibited a mildly acidic apparent pK a . Size-exclusion chromatography of RlActR purified in the relatively mild and harsh detergents 5-cyclohexyl-1-pentyl-β-D-maltoside and n-octyl-β-D-glucopyranoside revealed highly homogeneous oligomers and no disruption into monomers, indicating significant robustness of the RlActR oligomer. Cryo-electron microscopy and 2D classification of protein particles provided a projection structure identifying the oligomeric state of RlActR as a pentamer. Efficient establishment of a proton gradient across lipid membranes upon light illumination was demonstrated using RlActR-overexpressing E. coli cells and reconstituted RlActR proteoliposomes. In summary, these features make RlActR an attractive energizing building block for the bottom-up assembly of molecular systems for bionanotechnological applications. |
| format | Article |
| id | doaj-art-fae29c6ef03745e087f6fb9b0a804815 |
| institution | Kabale University |
| issn | 2045-2322 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Nature Portfolio |
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| series | Scientific Reports |
| spelling | doaj-art-fae29c6ef03745e087f6fb9b0a8048152025-02-09T12:30:00ZengNature PortfolioScientific Reports2045-23222025-02-0115111210.1038/s41598-025-88055-8Actinorhodopsin: an efficient and robust light-driven proton pump for bionanotechnological applicationsNooraldeen Ayoub0Nadia Djabeur1Daniel Harder2Jean-Marc Jeckelmann3Zöhre Ucurum4Stephan Hirschi5Dimitrios Fotiadis6Institute of Biochemistry and Molecular Medicine, University of BernInstitute of Biochemistry and Molecular Medicine, University of BernInstitute of Biochemistry and Molecular Medicine, University of BernInstitute of Biochemistry and Molecular Medicine, University of BernInstitute of Biochemistry and Molecular Medicine, University of BernInstitute of Biochemistry and Molecular Medicine, University of BernInstitute of Biochemistry and Molecular Medicine, University of BernAbstract Actinorhodopsins are encoded by a distinct group of microbial rhodopsin (MR) genes predominant in non-marine actinobacteria. Despite their role in the global energy cycle and potential for bionanotechnological applications, our understanding of actinorhodopsin proteins is limited. Here, we characterized the actinorhodopsin RlActR from the freshwater actinobacterium Rhodoluna lacicola, which conserves amino acid residues critical for light-driven proton pumping found in MRs. RlActR was efficiently overexpressed in Escherichia coli in milligram amounts and isolated with high purity and homogeneity. The purified RlActR absorbed green light and its primary proton acceptor exhibited a mildly acidic apparent pK a . Size-exclusion chromatography of RlActR purified in the relatively mild and harsh detergents 5-cyclohexyl-1-pentyl-β-D-maltoside and n-octyl-β-D-glucopyranoside revealed highly homogeneous oligomers and no disruption into monomers, indicating significant robustness of the RlActR oligomer. Cryo-electron microscopy and 2D classification of protein particles provided a projection structure identifying the oligomeric state of RlActR as a pentamer. Efficient establishment of a proton gradient across lipid membranes upon light illumination was demonstrated using RlActR-overexpressing E. coli cells and reconstituted RlActR proteoliposomes. In summary, these features make RlActR an attractive energizing building block for the bottom-up assembly of molecular systems for bionanotechnological applications.https://doi.org/10.1038/s41598-025-88055-8 |
| spellingShingle | Nooraldeen Ayoub Nadia Djabeur Daniel Harder Jean-Marc Jeckelmann Zöhre Ucurum Stephan Hirschi Dimitrios Fotiadis Actinorhodopsin: an efficient and robust light-driven proton pump for bionanotechnological applications Scientific Reports |
| title | Actinorhodopsin: an efficient and robust light-driven proton pump for bionanotechnological applications |
| title_full | Actinorhodopsin: an efficient and robust light-driven proton pump for bionanotechnological applications |
| title_fullStr | Actinorhodopsin: an efficient and robust light-driven proton pump for bionanotechnological applications |
| title_full_unstemmed | Actinorhodopsin: an efficient and robust light-driven proton pump for bionanotechnological applications |
| title_short | Actinorhodopsin: an efficient and robust light-driven proton pump for bionanotechnological applications |
| title_sort | actinorhodopsin an efficient and robust light driven proton pump for bionanotechnological applications |
| url | https://doi.org/10.1038/s41598-025-88055-8 |
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