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Baker BA, Gutiérrez-Preciado A, Rodríguez Del Río Á, McCarthy CGP, López-García P, Huerta-Cepas J, Susko E, Roger AJ, Eme L, Moreira D. Expanded phylogeny of extremely halophilic archaea shows multiple independent adaptations to hypersaline environments. Nat Microbiol 2024; 9:964-975. [PMID: 38519541 DOI: 10.1038/s41564-024-01647-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 02/20/2024] [Indexed: 03/25/2024]
Abstract
Extremely halophilic archaea (Haloarchaea, Nanohaloarchaeota, Methanonatronarchaeia and Halarchaeoplasmatales) thrive in saturating salt concentrations where they must maintain osmotic equilibrium with their environment. The evolutionary history of adaptations enabling salt tolerance remains poorly understood, in particular because the phylogeny of several lineages is conflicting. Here we present a resolved phylogeny of extremely halophilic archaea obtained using improved taxon sampling and state-of-the-art phylogenetic approaches designed to cope with the strong compositional biases of their proteomes. We describe two uncultured lineages, Afararchaeaceae and Asbonarchaeaceae, which break the long branches at the base of Haloarchaea and Nanohaloarchaeota, respectively. We obtained 13 metagenome-assembled genomes (MAGs) of these archaea from metagenomes of hypersaline aquatic systems of the Danakil Depression (Ethiopia). Our phylogenomic analyses including these taxa show that at least four independent adaptations to extreme halophily occurred during archaeal evolution. Gene-tree/species-tree reconciliation suggests that gene duplication and horizontal gene transfer played an important role in this process, for example, by spreading key genes (such as those encoding potassium transporters) across extremely halophilic lineages.
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Affiliation(s)
- Brittany A Baker
- Ecologie Systématique Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France
| | - Ana Gutiérrez-Preciado
- Ecologie Systématique Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France
| | - Álvaro Rodríguez Del Río
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CSIC), Madrid, Spain
| | - Charley G P McCarthy
- Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Purificación López-García
- Ecologie Systématique Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France
| | - Jaime Huerta-Cepas
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CSIC), Madrid, Spain
| | - Edward Susko
- Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Andrew J Roger
- Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Laura Eme
- Ecologie Systématique Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France.
| | - David Moreira
- Ecologie Systématique Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France.
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2
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Saliminasab M, Yamazaki Y, Palmateer A, Harris A, Schubert L, Langner P, Heberle J, Bondar AN, Brown LS. A Proteorhodopsin-Related Photosensor Expands the Repertoire of Structural Motifs Employed by Sensory Rhodopsins. J Phys Chem B 2023; 127:7872-7886. [PMID: 37694950 PMCID: PMC10519204 DOI: 10.1021/acs.jpcb.3c04032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/09/2023] [Indexed: 09/12/2023]
Abstract
Microbial rhodopsins are light-activated retinal-binding membrane proteins that perform a variety of ion transport and photosensory functions. They display several cases of convergent evolution where the same function is present in unrelated or very distant protein groups. Here we report another possible case of such convergent evolution, describing the biophysical properties of a new group of sensory rhodopsins. The first representative of this group was identified in 2004 but none of the members had been expressed and characterized. The well-studied haloarchaeal sensory rhodopsins interacting with methyl-accepting Htr transducers are close relatives of the halobacterial proton pump bacteriorhodopsin. In contrast, the sensory rhodopsins we describe here are relatives of proteobacterial proton pumps, proteorhodopsins, but appear to interact with Htr-like transducers likewise, even though they do not conserve the residues important for the interaction of haloarchaeal sensory rhodopsins with their transducers. The new sensory rhodopsins display many unusual amino acid residues, including those around the retinal chromophore; most strikingly, a tyrosine in place of a carboxyl counterion of the retinal Schiff base on helix C. To characterize their unique sequence motifs, we augment the spectroscopy and biochemistry data by structural modeling of the wild-type and three mutants. Taken together, the experimental data, bioinformatics sequence analyses, and structural modeling suggest that the tyrosine/aspartate complex counterion contributes to a complex water-mediated hydrogen-bonding network that couples the protonated retinal Schiff base to an extracellular carboxylic dyad.
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Affiliation(s)
- Maryam Saliminasab
- Department
of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Yoichi Yamazaki
- Division
of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Alyssa Palmateer
- Department
of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Andrew Harris
- Department
of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Luiz Schubert
- Experimental
Molecular Biophysics Group, Department of Physics, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Pit Langner
- Experimental
Molecular Biophysics Group, Department of Physics, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Joachim Heberle
- Experimental
Molecular Biophysics Group, Department of Physics, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Ana-Nicoleta Bondar
- University
of Bucharest, Faculty of Physics, Atomiştilor 405, Măgurele 077125, Romania
- Forschungszentrum
Jülich, Institute for Neuroscience and Medicine and Institute
for Advanced Simulations (IAS-5/INM-9), Computational Biomedicine, Wilhelm-Johnen Straße, 52428 Jülich, Germany
| | - Leonid S. Brown
- Department
of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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3
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Brück P, Wasser D, Soppa J. One Advantage of Being Polyploid: Prokaryotes of Various Phylogenetic Groups Can Grow in the Absence of an Environmental Phosphate Source at the Expense of Their High Genome Copy Numbers. Microorganisms 2023; 11:2267. [PMID: 37764113 PMCID: PMC10536925 DOI: 10.3390/microorganisms11092267] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 08/30/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
Genomic DNA has high phosphate content; therefore, monoploid prokaryotes need an external phosphate source or an internal phosphate storage polymer for replication and cell division. For two polyploid prokaryotic species, the halophilic archaeon Haloferax volcanii and the cyanobacterium Synechocystis PCC 6803, it has been reported that they can grow in the absence of an external phosphate source by reducing the genome copy number per cell. To unravel whether this feature might be widespread in and typical for polyploid prokaryotes, three additional polyploid prokaryotic species were analyzed in the present study, i.e., the alphaproteobacterium Zymomonas mobilis, the gammaproteobacterium Azotobacter vinelandii, and the haloarchaeon Halobacterium salinarum. Polyploid cultures were incubated in the presence and in the absence of external phosphate, growth was recorded, and genome copy numbers per cell were quantified. Limited growth in the absence of phosphate was observed for all three species. Phosphate was added to phosphate-starved cultures to verify that the cells were still viable and growth-competent. Remarkably, stationary-phase cells grown in the absence or presence of phosphate did not become monoploid but stayed oligoploid with about five genome copies per cell. As a negative control, it was shown that monoploid Escherichia coli cultures did not exhibit any growth in the absence of phosphate. Taken together, all five polyploid prokaryotic species that have been characterized until now can grow in the absence of environmental phosphate by reducing their genome copy numbers, indicating that cell proliferation outperforms other evolutionary advantages of polyploidy.
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Affiliation(s)
| | | | - Jörg Soppa
- Biocentre, Institute for Molecular Biosciences, Goethe University, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany (D.W.)
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Low Salt Influences Archaellum-Based Motility, Glycerol Metabolism, and Gas Vesicles Biogenesis in Halobacterium salinarum. Microorganisms 2022; 10:microorganisms10122442. [PMID: 36557695 PMCID: PMC9786353 DOI: 10.3390/microorganisms10122442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/05/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022] Open
Abstract
Halobacterium salinarum NRC-1 is an extremophile that grows optimally at 4.3 M NaCl concentration. In spite of being an established model microorganism for the archaea domain, direct comparisons between its proteome and transcriptome during osmotic stress are still not available. Through RNA-seq-based transcriptomics, we compared a low salt (2.6 M NaCl) stress condition with 4.3 M of NaCl and found 283 differentially expressed loci. The more commonly found classes of genes were: ABC-type transporters and transcription factors. Similarities, and most importantly, differences between our findings and previously published datasets in similar experimental conditions are discussed. We validated three important biological processes differentially expressed: gas vesicles production (due to down-regulation of gvpA1b, gvpC1b, gvpN1b, and gvpO1b); archaellum formation (due to down-regulation of arlI, arlB1, arlB2, and arlB3); and glycerol metabolism (due to up-regulation of glpA1, glpB, and glpC). Direct comparison between transcriptomics and proteomics showed 58% agreement between mRNA and protein level changes, pointing to post-transcriptional regulation candidates. From those genes, we highlight rpl15e, encoding for the 50S ribosomal protein L15e, for which we hypothesize an ionic strength-dependent conformational change that guides post-transcriptional processing of its mRNA and, thus, possible salt-dependent regulation of the translation machinery.
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Govorunova EG, Sineshchekov OA, Spudich JL. Emerging Diversity of Channelrhodopsins and Their Structure-Function Relationships. Front Cell Neurosci 2022; 15:800313. [PMID: 35140589 PMCID: PMC8818676 DOI: 10.3389/fncel.2021.800313] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/28/2021] [Indexed: 12/12/2022] Open
Abstract
Cation and anion channelrhodopsins (CCRs and ACRs, respectively) from phototactic algae have become widely used as genetically encoded molecular tools to control cell membrane potential with light. Recent advances in polynucleotide sequencing, especially in environmental samples, have led to identification of hundreds of channelrhodopsin homologs in many phylogenetic lineages, including non-photosynthetic protists. Only a few CCRs and ACRs have been characterized in detail, but there are indications that ion channel function has evolved within the rhodopsin superfamily by convergent routes. The diversity of channelrhodopsins provides an exceptional platform for the study of structure-function evolution in membrane proteins. Here we review the current state of channelrhodopsin research and outline perspectives for its further development.
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Lokiarchaeota archaeon schizorhodopsin-2 (LaSzR2) is an inward proton pump displaying a characteristic feature of acid-induced spectral blue-shift. Sci Rep 2020; 10:20857. [PMID: 33257762 PMCID: PMC7704677 DOI: 10.1038/s41598-020-77936-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 10/29/2020] [Indexed: 11/25/2022] Open
Abstract
The photoreactive protein rhodopsin is widespread in microorganisms and has a variety of photobiological functions. Recently, a novel phylogenetically distinctive group named ‘schizorhodopsin (SzR)’ has been identified as an inward proton pump. We performed functional and spectroscopic studies on an uncharacterised schizorhodopsin from the phylum Lokiarchaeota archaeon. The protein, LaSzR2, having an all-trans-retinal chromophore, showed inward proton pump activity with an absorption maximum at 549 nm. The pH titration experiments revealed that the protonated Schiff base of the retinal chromophore (Lys188, pKa = 12.3) is stabilised by the deprotonated counterion (presumably Asp184, pKa = 3.7). The flash-photolysis experiments revealed the presence of two photointermediates, K and M. A proton was released and uptaken from bulk solution upon the formation and decay of the M intermediate. During the M-decay, the Schiff base was reprotonated by the proton from a proton donating residue (presumably Asp172). These properties were compared with other inward (SzRs and xenorhodopsins, XeRs) and outward proton pumps. Notably, LaSzR2 showed acid-induced spectral ‘blue-shift’ due to the protonation of the counterion, whereas outward proton pumps showed opposite shifts (red-shifts). Thus, we can distinguish between inward and outward proton pumps by the direction of the acid-induced spectral shift.
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Yamamoto A, Tsukamoto T, Suzuki K, Hashimoto E, Kobashigawa Y, Shibasaki K, Uchida T, Inagaki F, Demura M, Ishimori K. Spectroscopic Characterization of Halorhodopsin Reconstituted into Nanodisks Using Native Lipids. Biophys J 2020; 118:2853-2865. [PMID: 32396848 DOI: 10.1016/j.bpj.2020.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 04/06/2020] [Accepted: 04/22/2020] [Indexed: 10/24/2022] Open
Abstract
We successfully reconstituted single Natronomonas pharaonis halorhodopsin (NpHR) trimers into a nanodisk (ND) using the native archaeal lipid (NL) and an artificial lipid having a zwitterionic headgroup, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Incorporation of single trimeric NpHR into NDs was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, size-exclusion chromatography, and visible circular dichroism spectroscopy. The Cl- binding affinity of NpHR in NDs using NL (NL-ND NpHR) or POPC (POPC-ND NpHR) was examined by absorption spectroscopy, showing that the Cl--releasing affinities (Kd,N↔O) of these ND-reconstituted NpHRs are more than 10 times higher than that obtained from native NpHR membrane fragments (MFs) harvested from a NpHR-overexpressing archaeal strain (MF NpHR). The photoreaction kinetics of these ND-reconstituted NpHRs revealed that the Cl- uptake was faster than that of MF NpHR. These differences in the Cl--releasing and uptake properties of ND-reconstituted NpHRs and MF NpHR may arise from suppression of protein conformational changes associated with Cl- release from the trimeric NpHR caused by ND reconstitution, conformational perturbation in the trimeric state, and loss of the trimer-trimer interactions. On the other hand, POPC-ND NpHR demonstrated accelerated Cl- uptake compared to NL-ND NpHR, suggesting that the negative charge on the archaeal membrane surface regulates the photocycle of NpHR. Although NL-ND NpHR and MF NpHR are embedded in the same lipid, the lower Cl--binding affinity at the initial state (Kd,initial) and faster recovering from the NpHR' state to the original state of the photoreaction cycle were observed for NL-ND NpHR, probably because of insufficient interactions with a chromophore in the native membrane, bacterioruberin in reconstituted NDs. Our results indicate that specific interactions of NpHR with surrounding lipids and bacterioruberin, structural flexibility of the membrane, and interactions between trimeric NpHRs may be necessary for efficient Cl- pumping.
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Affiliation(s)
- Ayumi Yamamoto
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | - Takashi Tsukamoto
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan
| | - Kenshiro Suzuki
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | - Eri Hashimoto
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | | | - Kousuke Shibasaki
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Takeshi Uchida
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Fuyuhiko Inagaki
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Makoto Demura
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan.
| | - Koichiro Ishimori
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Japan.
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8
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Abstract
Microbial rhodopsins (MRs) are a large family of photoactive membrane proteins, found in microorganisms belonging to all kingdoms of life, with new members being constantly discovered. Among the MRs are light-driven proton, cation and anion pumps, light-gated cation and anion channels, and various photoreceptors. Due to their abundance and amenability to studies, MRs served as model systems for a great variety of biophysical techniques, and recently found a great application as optogenetic tools. While the basic aspects of microbial rhodopsins functioning have been known for some time, there is still a plenty of unanswered questions. This chapter presents and summarizes the available knowledge, focusing on the functional and structural studies.
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Affiliation(s)
- Ivan Gushchin
- Moscow Institute of Physics and Technology, Dolgoprudniy, Russia.
| | - Valentin Gordeliy
- Moscow Institute of Physics and Technology, Dolgoprudniy, Russia.
- University of Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France.
- Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Jülich, Jülich, Germany.
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9
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Kim SY, Yoon SR, Han S, Yun Y, Jung KH. A role of Anabaena sensory rhodopsin transducer (ASRT) in photosensory transduction. Mol Microbiol 2014; 93:403-14. [PMID: 24798792 DOI: 10.1111/mmi.12635] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2014] [Indexed: 12/13/2022]
Abstract
In 2003, Anabaena sensory rhodopsin (ASR), a membrane-bound light sensor protein, was discovered in cyanobacteria. Since then, a large number of functions have been described for ASR, based on protein biochemical and biophysical studies. However, no study has determined the in vivo mechanism of photosensory transduction for ASR and its transducer protein (ASRT). Here, we aimed to determine the role of ASRT in physiological photo-regulation. ASRT is known to be related to photochromism, because it regulates the expression of phycocyanin (cpc-gene) and phycoerythrocyanin (pec gene), two major proteins of the phycobilisome in cyanobacteria. By examining wild type and knockout mutant Anabaena cells, we showed that ASRT repressed the expression of these two genes. We also demonstrated physical interactions between ASRT, ASR, and the promoter regions of cpc, pec, kaiABC (circadian clock gene) and the asr operon, both in vitro and in vivo. Binding assays indicated that ASRT had different sites of interaction for binding to ASR and DNA promoter regions. ASRT also influenced the retinal re-isomerization rate in dark through a physical interaction with ASR, and it regulated reporter gene expression in vivo. These results suggested that ASRT relayed the photosignal from ASR and directly regulated gene expression.
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Affiliation(s)
- So Young Kim
- Department of Life Science and Institute of Biological Interfaces, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul, 121-742, Korea
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10
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Natarajan J, Schultz A, Kurz U, Schultz JE. Biochemical characterization of the tandem HAMP domain fromNatronomonas pharaonisas an intraprotein signal transducer. FEBS J 2014; 281:3218-27. [DOI: 10.1111/febs.12855] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 04/17/2014] [Accepted: 05/16/2014] [Indexed: 01/21/2023]
Affiliation(s)
- Janani Natarajan
- Pharmazeutische Biochemie, Pharmazeutisches Institut, Universität Tübingen, Germany
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11
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Spudich JL, Sineshchekov OA, Govorunova EG. Mechanism divergence in microbial rhodopsins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:546-52. [PMID: 23831552 DOI: 10.1016/j.bbabio.2013.06.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 06/15/2013] [Accepted: 06/17/2013] [Indexed: 10/26/2022]
Abstract
A fundamental design principle of microbial rhodopsins is that they share the same basic light-induced conversion between two conformers. Alternate access of the Schiff base to the outside and to the cytoplasm in the outwardly open "E" conformer and cytoplasmically open "C" conformer, respectively, combined with appropriate timing of pKa changes controlling Schiff base proton release and uptake make the proton path through the pumps vectorial. Phototaxis receptors in prokaryotes, sensory rhodopsins I and II, have evolved new chemical processes not found in their proton pump ancestors, to alter the consequences of the conformational change or modify the change itself. Like proton pumps, sensory rhodopsin II undergoes a photoinduced E→C transition, with the C conformer a transient intermediate in the photocycle. In contrast, one light-sensor (sensory rhodopsin I bound to its transducer HtrI) exists in the dark as the C conformer and undergoes a light-induced C→E transition, with the E conformer a transient photocycle intermediate. Current results indicate that algal phototaxis receptors channelrhodopsins undergo redirected Schiff base proton transfers and a modified E→C transition which, contrary to the proton pumps and other sensory rhodopsins, is not accompanied by the closure of the external half-channel. The article will review our current understanding of how the shared basic structure and chemistry of microbial rhodopsins have been modified during evolution to create diverse molecular functions: light-driven ion transport and photosensory signaling by protein-protein interaction and light-gated ion channel activity. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.
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Affiliation(s)
- John L Spudich
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, 6431 Fannin St., MSB6.130, Houston, TX 77030, USA.
| | - Oleg A Sineshchekov
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, 6431 Fannin St., MSB6.130, Houston, TX 77030, USA
| | - Elena G Govorunova
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, 6431 Fannin St., MSB6.130, Houston, TX 77030, USA
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12
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Sudo Y, Okazaki A, Ono H, Yagasaki J, Sugo S, Kamiya M, Reissig L, Inoue K, Ihara K, Kandori H, Takagi S, Hayashi S. A blue-shifted light-driven proton pump for neural silencing. J Biol Chem 2013; 288:20624-32. [PMID: 23720753 DOI: 10.1074/jbc.m113.475533] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ion-transporting rhodopsins are widely utilized as optogenetic tools both for light-induced neural activation and silencing. The most studied representative is Bacteriorhodopsin (BR), which absorbs green/red light (∼570 nm) and functions as a proton pump. Upon photoexcitation, BR induces a hyperpolarization across the membrane, which, if incorporated into a nerve cell, results in its neural silencing. In this study, we show that several residues around the retinal chromophore, which are completely conserved among BR homologs from the archaea, are involved in the spectral tuning in a BR homolog (HwBR) and that the combination mutation causes a large spectral blue shift (λmax = 498 nm) while preserving the robust pumping activity. Quantum mechanics/molecular mechanics calculations revealed that, compared with the wild type, the β-ionone ring of the chromophore in the mutant is rotated ∼130° because of the lack of steric hindrance between the methyl groups of the retinal and the mutated residues, resulting in the breakage of the π conjugation system on the polyene chain of the retinal. By the same mutations, similar spectral blue shifts are also observed in another BR homolog, archearhodopsin-3 (also called Arch). The color variant of archearhodopsin-3 could be successfully expressed in the neural cells of Caenorhabditis elegans, and illumination with blue light (500 nm) led to the effective locomotory paralysis of the worms. Thus, we successfully produced a blue-shifted proton pump for neural silencing.
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Affiliation(s)
- Yuki Sudo
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan.
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13
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Wand A, Gdor I, Zhu J, Sheves M, Ruhman S. Shedding New Light on Retinal Protein Photochemistry. Annu Rev Phys Chem 2013; 64:437-58. [DOI: 10.1146/annurev-physchem-040412-110148] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Amir Wand
- Institute of Chemistry and the Farkas Center for Light-Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel;
| | - Itay Gdor
- Institute of Chemistry and the Farkas Center for Light-Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel;
| | - Jingyi Zhu
- Institute of Chemistry and the Farkas Center for Light-Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel;
| | - Mordechai Sheves
- Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sanford Ruhman
- Institute of Chemistry and the Farkas Center for Light-Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel;
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14
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Salt bridge in the conserved His-Asp cluster inGloeobacterrhodopsin contributes to trimer formation. FEBS Lett 2013; 587:322-7. [DOI: 10.1016/j.febslet.2012.12.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 12/12/2012] [Accepted: 12/13/2012] [Indexed: 12/18/2022]
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15
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Gehring WJ. The evolution of vision. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 3:1-40. [DOI: 10.1002/wdev.96] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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16
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Nishikata K, Ikeguchi M, Kidera A. Comparative simulations of the ground state and the M-intermediate state of the sensory rhodopsin II-transducer complex with a HAMP domain model. Biochemistry 2012; 51:5958-66. [PMID: 22757657 DOI: 10.1021/bi300696b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The complex of sensory rhodopsin II (SRII) and its cognate transducer HtrII (2:2 SRII-HtrII complex) consists of a photoreceptor and its signal transducer, respectively, associated with negative phototaxis in extreme halophiles. In this study to investigate how photoexcitation in SRII affects the structures of the complex, we conducted two series of molecular dynamics simulations of the complex of SRII and truncated HtrII (residues 1-136) of Natronomonas pharaonis linked with a modeled HAMP domain in the lipid bilayer using the two crystal structures of the ground state and the M-intermediate state as the starting structures. The simulation results showed significant enhancements of the structural differences observed between the two crystal structures. Helix F of SRII showed an outward motion, and the C-terminal end of transmembrane domain 2 (TM2) in HtrII rotated by ∼10°. The most significant structural changes were observed in the overall orientations of the two SRII molecules, closed in the ground state and open in the M-state. This change was attributed to substantial differences in the structure of the four-helix bundle of the HtrII dimer causing the apparent rotation of TM2. These simulation results established the structural basis for the various experimental observations explaining the structural differences between the ground state and the M-intermediate state.
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Affiliation(s)
- Koro Nishikata
- Graduate School of Nanobioscience, Yokohama City University, Yokohama 230-0045, Japan
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17
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Wang J, Sasaki J, Tsai AL, Spudich JL. HAMP domain signal relay mechanism in a sensory rhodopsin-transducer complex. J Biol Chem 2012; 287:21316-25. [PMID: 22511775 DOI: 10.1074/jbc.m112.344622] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The phototaxis receptor complex composed of sensory rhodopsin II (SRII) and the transducer subunit HtrII mediates photorepellent responses in haloarchaea. Light-activated SRII transmits a signal through two HAMP switch domains (HAMP1 and HAMP2) in HtrII that bridge the photoreceptive membrane domain of the complex and the cytoplasmic output kinase-modulating domain. HAMP domains, widespread signal relay modules in prokaryotic sensors, consist of four-helix bundles composed of two helices, AS1 and AS2, from each of two dimerized transducer subunits. To examine their molecular motion during signal transmission, we incorporated SRII-HtrII dimeric complexes in nanodiscs to allow unrestricted probe access to the cytoplasmic side HAMP domains. Spin-spin dipolar coupling measurements confirmed that in the nanodiscs, SRII photoactivation induces helix movement in the HtrII membrane domain diagnostic of transducer activation. Labeling kinetics of a fluorescein probe in monocysteine-substituted HAMP1 mutants revealed a light-induced shift of AS2 against AS1 by one-half α-helix turn with minimal other changes. An opposite shift of AS2 against AS1 in HAMP2 at the corresponding positions supports the proposal from x-ray crystal structures by Airola et al. (Airola, M. V., Watts, K. J., Bilwes, A. M., and Crane, B. R. (2010) Structure 18, 436-448) that poly-HAMP chains undergo alternating opposite interconversions to relay the signal. Moreover, we found that haloarchaeal cells expressing a HAMP2-deleted SRII-HtrII exhibit attractant phototaxis, opposite from the repellent phototaxis mediated by the wild-type di-HAMP SRII-HtrII complex. The opposite conformational changes and corresponding opposite output signals of HAMP1 and HAMP2 imply a signal transmission mechanism entailing small shifts in helical register between AS1 and AS2 alternately in opposite directions in adjacent HAMPs.
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Affiliation(s)
- Jihong Wang
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, Houston, Texas 77030, USA
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18
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A transporter converted into a sensor, a phototaxis signaling mutant of bacteriorhodopsin at 3.0 Å. J Mol Biol 2012; 415:455-63. [PMID: 22123198 PMCID: PMC3628824 DOI: 10.1016/j.jmb.2011.11.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 11/14/2011] [Accepted: 11/15/2011] [Indexed: 01/07/2023]
Abstract
Bacteriorhodopsin (BR) and sensory rhodopsin II (SRII), homologous photoactive proteins in haloarchaea, have different molecular functions. BR is a light-driven proton pump, whereas SRII is a phototaxis receptor that transmits a light-induced conformational change to its transducer HtrII. Despite these distinctly different functions, a single residue substitution, Ala215 to Thr215 in the BR retinal-binding pocket, enables its photochemical reactions to transmit signals to HtrII and mediate phototaxis. We pursued a crystal structure of the signaling BR mutant (BR_A215T) to determine the structural changes caused by the A215T mutation and to assess what new photochemistry is likely to be introduced into the BR photoactive site. We crystallized BR_A215T from bicelles and solved its structure to 3.0 Å resolution to enable an atomic-level comparison. The analysis was complemented by molecular dynamics simulation of BR mutated in silico. Three main conclusions regarding the roles of photoactive site residues in signaling emerge from the comparison of BR_A215T, BR, and SRII structures: (i) the Thr215 residue in signaling BR is positioned nearly identically with respect to the retinal chromophore as in SRII, consistent with its role in producing a steric conflict with the retinal C₁₄ group during photoisomerization, proposed earlier to be essential for SRII signaling from vibrational spectroscopy and motility measurements; (ii) Tyr174-Thr204 hydrogen bonding, critical in SRII signaling and mimicked in signaling BR, is likely auxiliary, for example, to maintain Thr204 in the proper position for the steric trigger to occur; and (iii) the primary role of Arg72 in SRII is spectral tuning and not signaling.
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19
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Bayraktar H, Fields AP, Kralj JM, Spudich JL, Rothschild KJ, Cohen AE. Ultrasensitive measurements of microbial rhodopsin photocycles using photochromic FRET. Photochem Photobiol 2012; 88:90-7. [PMID: 22010969 PMCID: PMC3253248 DOI: 10.1111/j.1751-1097.2011.01011.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microbial rhodopsins are an important class of light-activated transmembrane proteins whose function is typically studied on bulk samples. Herein, we apply photochromic fluorescence resonance energy transfer to investigate the dynamics of these proteins with sensitivity approaching the single-molecule limit. The brightness of a covalently linked organic fluorophore is modulated by changes in the absorption spectrum of the endogenous retinal chromophore that occur as the molecule undergoes a light-activated photocycle. We studied the photocycles of blue-absorbing proteorhodopsin and sensory rhodopsin II (SRII). Clusters of 2-3 molecules of SRII clearly showed a light-induced photocycle. Single molecules of SRII showed a photocycle upon signal averaging over several illumination cycles.
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Affiliation(s)
| | | | | | - John L. Spudich
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, Texas
| | - Kenneth J. Rothschild
- Department of Physics and Photonics Center, Boston University, Boston, Massachusetts
| | - Adam E. Cohen
- Department of Chemistry and Chemical Biology
- Department of Physics, Harvard University, Cambridge, Massachusetts
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20
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Gushchin I, Reshetnyak A, Borshchevskiy V, Ishchenko A, Round E, Grudinin S, Engelhard M, Bldt G, Gordeliy V. Active State of Sensory Rhodopsin II: Structural Determinants for Signal Transfer and Proton Pumping. J Mol Biol 2011; 412:591-600. [DOI: 10.1016/j.jmb.2011.07.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 06/23/2011] [Accepted: 07/13/2011] [Indexed: 10/17/2022]
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21
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Sasaki J, Takahashi H, Furutani Y, Kandori H, Spudich JL. Sensory rhodopsin-I as a bidirectional switch: opposite conformational changes from the same photoisomerization. Biophys J 2011; 100:2178-83. [PMID: 21539785 DOI: 10.1016/j.bpj.2011.03.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 03/21/2011] [Accepted: 03/22/2011] [Indexed: 11/29/2022] Open
Abstract
The phototaxis receptor sensory rhodopsin I (SRI) exists in two protein conformations, each of which is converted to the other by light absorption by the protein's retinylidene chromophore. One conformer inhibits a histidine-kinase attached to its bound transducer HtrI and its formation induces attractant motility responses, whereas the other conformer activates the kinase and its formation induces repellent responses. We performed Fourier transform infrared spectroscopy with temperature, pH, and mutation-induced shifts in the conformer equilibrium, and found that both conformers when present in the unphotolyzed dark state contain an all-trans retinal configuration that is photoisomerized to 13-cis, i.e., the same photoisomerization causes the opposite conformational change in the photointerconvertible pair of conformers depending on which conformer is present in the dark. Therefore, switching between the protein global conformations that define the two conformers is independent of the direction of isomerization. Insights into this phenomenon are gained from analysis of the evolution of the receptor from light-driven proton pumps, which use similar conformers for transport. The versatility of the conformational changes of microbial rhodopsins, including conformer interexchangeability in the photocycle as shown here, is likely a significant factor in the evolution of the diverse functionality of this protein family.
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Affiliation(s)
- Jun Sasaki
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston, Texas, USA
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22
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Sasaki J, Tsai AL, Spudich JL. Opposite displacement of helix F in attractant and repellent signaling by sensory rhodopsin-Htr complexes. J Biol Chem 2011; 286:18868-77. [PMID: 21454480 DOI: 10.1074/jbc.m110.200345] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two forms of the phototaxis receptor sensory rhodopsin I distinguished by differences in its photoactive site have been shown to be directly correlated with attractant and repellent signaling by the dual-signaling protein. In prior studies, differences in the photoactive site defined the two forms, namely the direction of light-induced proton transfer from the chromophore and the pK(a) of an Asp counterion to the protonated chromophore. Here, we show by both in vivo and in vitro measurements that the two forms are distinct protein conformers with structural similarities to two conformers seen in the light-driven proton transport cycle of the related protein bacteriorhodopsin. Measurements of spontaneous cell motility reversal frequencies, an in vivo measure of histidine kinase activity in the phototaxis system, indicate that the two forms are a photointerconvertible pair, with one conformer activating and the other inhibiting the kinase. Protein conformational changes in these photoconversions monitored by site-directed spin labeling show that opposite structural changes in helix F, distant from the photoactive site, correspond to the opposite phototaxis signals. The results provide the first direct evidence that displacements of helix F are directly correlated with signaling and impact our understanding of the sensory rhodopsin I signaling mechanism and the evolution of diverse functionality in this protein family.
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Affiliation(s)
- Jun Sasaki
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston, Texas 77030, USA
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23
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Mizuno M, Sudo Y, Homma M, Mizutani Y. Direct Observation of the Structural Change of Tyr174 in the Primary Reaction of Sensory Rhodopsin II. Biochemistry 2011; 50:3170-80. [DOI: 10.1021/bi101817y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yuki Sudo
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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24
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Sudo Y, Yuasa Y, Shibata J, Suzuki D, Homma M. Spectral tuning in sensory rhodopsin I from Salinibacter ruber. J Biol Chem 2011; 286:11328-36. [PMID: 21288897 DOI: 10.1074/jbc.m110.187948] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Organisms utilize light as energy sources and as signals. Rhodopsins, which have seven transmembrane α-helices with retinal covalently linked to a conserved Lys residue, are found in various organisms as distant in evolution as bacteria, archaea, and eukarya. One of the most notable properties of rhodopsin molecules is the large variation in their absorption spectrum. Sensory rhodopsin I (SRI) and sensory rhodopsin II (SRII) function as photosensors and have similar properties (retinal composition, photocycle, structure, and function) except for their λ(max) (SRI, ∼560 nm; SRII, ∼500 nm). An expression system utilizing Escherichia coli and the high protein stability of a newly found SRI-like protein, SrSRI, enables studies of mutant proteins. To determine the residue contributing to the spectral shift from SRI to SRII, we constructed various SRI mutants, in which individual residues were substituted with the corresponding residues of SRII. Three such mutants of SrSRI showed a large spectral blue-shift (>14 nm) without a large alteration of their retinal composition. Two of them, A136Y and A200T, are newly discovered color tuning residues. In the triple mutant, the λ(max) was 525 nm. The inverse mutation of SRII (F134H/Y139A/T204A) generated a spectral-shifted SRII toward longer wavelengths, although the effect is smaller than in the case of SRI, which is probably due to the lack of anion binding in the SRII mutant. Thus, half of the spectral shift from SRI to SRII could be explained by only those three residues taking into account the effect of Cl(-) binding.
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Affiliation(s)
- Yuki Sudo
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan.
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25
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Gushchin IY, Gordeliy VI, Grudinin S. Role of the HAMP domain region of sensory rhodopsin transducers in signal transduction. Biochemistry 2010; 50:574-80. [PMID: 21162553 DOI: 10.1021/bi101032a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Archaea are able to sense light via the complexes of sensory rhodopsins I and II and their corresponding chemoreceptor-like transducers HtrI and HtrII. Though generation of the signal has been studied in detail, the mechanism of its propagation to the cytoplasm remains obscured. The cytoplasmic part of the transducer consists of adaptation and kinase activity modulating regions, connected to transmembrane helices via two HAMP (histidine kinases, adenylyl cyclases, methyl-accepting chemotaxis proteins, phosphatases) domains. The inter-HAMP region of Natronomonas pharaonis HtrII (NpHtrII) was found to be α-helical [Hayashi, K., et al. (2007) Biochemistry 46, 14380-14390]. We studied the inter-HAMP regions of NpHtrII and other phototactic signal transducers by means of molecular dynamics. Their structure is found to be a bistable asymmetric coiled coil, in which the protomers are longitudinally shifted by ~1.3 Å. The free energy penalty for the symmetric structure is estimated to be 1.2-1.5 kcal/mol depending on the molarity of the solvent. Both flanking HAMP domains are mechanistically coupled to the inter-HAMP region and are asymmetric. The longitudinal shift in the inter-HAMP region is coupled with the in-plane displacement of the cytoplasmic part by 8.6 Å relative to the transmembrane part. The established properties suggest that (1) the signal may be transduced through the inter-HAMP domain switching and (2) the inter-HAMP region may allow cytoplasmic parts of the transducers to come sufficiently close to each other to form oligomers.
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Affiliation(s)
- Ivan Yu Gushchin
- Research-educational Centre Bionanophysics, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia
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26
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Abstract
HAMP domains mediate input-output signaling in histidine kinases, adenylyl cyclases, methyl-accepting chemotaxis proteins, and some phosphatases. HAMP subunits have two 16-residue amphiphilic helices (AS1, AS2) joined by a 14- to 15-residue connector segment. Two alternative HAMP structures in these homodimeric signaling proteins have been described: HAMP(A), a tightly packed, parallel, four-helix bundle; and HAMP(B), a more loosely packed bundle with an altered AS2/AS2' packing arrangement. Stimulus-induced conformational changes probably modulate HAMP signaling by shifting the relative stabilities of these opposing structural states. Changes in AS2/AS2' packing, in turn, modulate output signals by altering structural interactions between output helices through heptad repeat stutters that produce packing phase clashes. Output helices that are too tightly or too loosely packed most likely produce kinase-off output states, whereas kinase-on states require an intermediate range of HAMP stabilities and dynamic behaviors. A three-state, dynamic bundle signaling model best accounts for the signaling properties of chemoreceptor mutants and may apply to other transducers as well.
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Affiliation(s)
- John S Parkinson
- Biology Department, University of Utah, Salt Lake City, Utah 84112, USA.
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27
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Sudo Y, Ihara K, Kobayashi S, Suzuki D, Irieda H, Kikukawa T, Kandori H, Homma M. A microbial rhodopsin with a unique retinal composition shows both sensory rhodopsin II and bacteriorhodopsin-like properties. J Biol Chem 2010; 286:5967-76. [PMID: 21135094 DOI: 10.1074/jbc.m110.190058] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Rhodopsins possess retinal chromophore surrounded by seven transmembrane α-helices, are widespread in prokaryotes and in eukaryotes, and can be utilized as optogenetic tools. Although rhodopsins work as distinctly different photoreceptors in various organisms, they can be roughly divided according to their two basic functions, light-energy conversion and light-signal transduction. In microbes, light-driven proton transporters functioning as light-energy converters have been modified by evolution to produce sensory receptors that relay signals to transducer proteins to control motility. In this study, we cloned and characterized two newly identified microbial rhodopsins from Haloquadratum walsbyi. One of them has photochemical properties and a proton pumping activity similar to the well known proton pump bacteriorhodopsin (BR). The other, named middle rhodopsin (MR), is evolutionarily transitional between BR and the phototactic sensory rhodopsin II (SRII), having an SRII-like absorption maximum, a BR-like photocycle, and a unique retinal composition. The wild-type MR does not have a light-induced proton pumping activity. On the other hand, a mutant MR with two key hydrogen-bonding residues located at the interaction surface with the transducer protein HtrII shows robust phototaxis responses similar to SRII, indicating that MR is potentially capable of the signaling. These results demonstrate that color tuning and insertion of the critical threonine residue occurred early in the evolution of sensory rhodopsins. MR may be a missing link in the evolution from type 1 rhodopsins (microorganisms) to type 2 rhodopsins (animals), because it is the first microbial rhodopsin known to have 11-cis-retinal similar to type 2 rhodopsins.
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Affiliation(s)
- Yuki Sudo
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
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28
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Sineshchekov OA, Sasaki J, Wang J, Spudich JL. Attractant and repellent signaling conformers of sensory rhodopsin-transducer complexes. Biochemistry 2010; 49:6696-704. [PMID: 20590098 PMCID: PMC2914491 DOI: 10.1021/bi100798w] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Attractant and repellent signaling conformers of the dual-signaling phototaxis receptor sensory rhodopsin I and its transducer subunit (SRI−HtrI) have recently been distinguished experimentally by the opposite connection of their retinylidene protonated Schiff bases to the outwardly located periplasmic side and inwardly located cytoplasmic side. Here we show that the pKa of the outwardly located Asp76 counterion in the outwardly connected conformer is lowered by ∼1.5 units from that of the inwardly connected conformer. The pKa difference enables quantitative determination of the relative amounts of the two conformers in wild-type cells and behavioral mutants prior to photoexcitation, comparison of their absorption spectra, and determination of their relative signaling efficiency. We have shown that the one-photon excitation of the SRI−HtrI attractant conformer causes a Schiff base connectivity switch from inwardly connected to outwardly connected states in the attractant signaling photoreaction. Conversely, a second near-UV photon drives the complex back to the inwardly connected conformer in the repellent signaling photoreaction. The results suggest a model of the color-discriminating dual-signaling mechanism in which phototaxis responses (his-kinase modulation) result from the photointerconversion of the two oppositely connected SRI−HtrI conformers by one-photon and two-photon activation. Furthermore, we find that the related repellent phototaxis SRII−HtrII receptor complex has an outwardly connected retinylidene Schiff base like the repellent signaling forms of the SRI−HtrI complex, indicating the general applicability of macro conformational changes, which can be detected by the connectivity switch, to phototaxis signaling by sensory rhodopsin−transducer complexes.
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Affiliation(s)
- Oleg A Sineshchekov
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston, Texas 77030, USA
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29
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Abstract
Microbial rhodopsins, a diverse group of photoactive proteins found in Archaea, Bacteria, and Eukarya, function in photosensing and photoenergy harvesting and may have been present in the resource-limited early global environment. Four different physiological functions have been identified and characterized for nearly 5,000 retinal-binding photoreceptors, these being ion transporters that transport proton or chloride and sensory rhodopsins that mediate light-attractant and/or -repellent responses. The greatest number of rhodopsins previously observed in a single archaeon had been four. Here, we report a newly discovered six-rhodopsin system in a single archaeon, Haloarcula marismortui, which shows a more diverse absorbance spectral distribution than any previously known rhodopsin system, and, for the first time, two light-driven proton transporters that respond to the same wavelength. All six rhodopsins, the greatest number ever identified in a single archaeon, were first shown to be expressed in H. marismortui, and these were then overexpressed in Escherichia coli. The proteins were purified for absorption spectra and photocycle determination, followed by measurement of ion transportation and phototaxis. The results clearly indicate the existence of a proton transporter system with two isochromatic rhodopsins and a new type of sensory rhodopsin-like transducer in H. marismortui.
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30
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Etzkorn M, Seidel K, Li L, Martell S, Geyer M, Engelhard M, Baldus M. Complex formation and light activation in membrane-embedded sensory rhodopsin II as seen by solid-state NMR spectroscopy. Structure 2010; 18:293-300. [PMID: 20223212 DOI: 10.1016/j.str.2010.01.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2009] [Revised: 12/23/2009] [Accepted: 01/22/2010] [Indexed: 11/18/2022]
Abstract
Microbial rhodopsins execute diverse biological functions in the cellular membrane. A mechanistic understanding of their functional profile is, however, still limited. We used solid-state NMR (ssNMR) spectroscopy to study structure and dynamics of a 2 x 400 amino acid sensory rhodopsin/transducer (SRII/HtrII) complex from Natronomonas pharaonis in a natural membrane environment. We found a receptor-transducer binding interface in the ground state that significantly extends beyond the available X-ray structure. This binding domain involves the EF loop of the receptor and stabilizes the functionally relevant, directly adjacent HAMP domain of the transducer. Using 2D ssNMR difference spectroscopy, we identified protein residues that may act as a functional module around the retinal binding site during the early events of protein activation. These latter protein segments, the inherent plasticity of the HAMP domain, and the observation of an extended SRII/HtrII membrane-embedded interface may be crucial components for optimal signal relay efficiency across the cell membrane.
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Affiliation(s)
- Manuel Etzkorn
- Department for NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen, Germany
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31
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Suzuki D, Irieda H, Homma M, Kawagishi I, Sudo Y. Phototactic and chemotactic signal transduction by transmembrane receptors and transducers in microorganisms. SENSORS 2010; 10:4010-39. [PMID: 22319339 PMCID: PMC3274258 DOI: 10.3390/s100404010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 03/29/2010] [Accepted: 04/09/2010] [Indexed: 12/17/2022]
Abstract
Microorganisms show attractant and repellent responses to survive in the various environments in which they live. Those phototaxic (to light) and chemotaxic (to chemicals) responses are regulated by membrane-embedded receptors and transducers. This article reviews the following: (1) the signal relay mechanisms by two photoreceptors, Sensory Rhodopsin I (SRI) and Sensory Rhodopsin II (SRII) and their transducers (HtrI and HtrII) responsible for phototaxis in microorganisms; and (2) the signal relay mechanism of a chemoreceptor/transducer protein, Tar, responsible for chemotaxis in E. coli. Based on results mainly obtained by our group together with other findings, the possible molecular mechanisms for phototaxis and chemotaxis are discussed.
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Affiliation(s)
- Daisuke Suzuki
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan; E-Mails: (D.S.); (H.I.); (M.H.)
| | - Hiroki Irieda
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan; E-Mails: (D.S.); (H.I.); (M.H.)
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan; E-Mails: (D.S.); (H.I.); (M.H.)
| | - Ikuro Kawagishi
- Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, 184-8584, Japan; E-Mail: (I.K.)
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, 184-8584, Japan
| | - Yuki Sudo
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan; E-Mails: (D.S.); (H.I.); (M.H.)
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama, 332-0012, Japan
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +81-52-789-2993; Fax: +81-52-789-3001
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32
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Transmembrane polar interactions are required for signaling in the Escherichia coli sensor kinase PhoQ. Proc Natl Acad Sci U S A 2010; 107:8141-6. [PMID: 20404199 DOI: 10.1073/pnas.1003166107] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PhoQ is the transmembrane sensor histidine kinase of the bacterial phoPQ two-component system, which detects and responds to divalent cations and to antimicrobial peptides, and can trigger virulence. Despite their ubiquitous importance in bacterial signaling, the structure and mechanism of the sensor kinases are not fully understood. In particular, the mechanism by which the signal is propagated through the transmembrane (TM) region remains unclear. We have identified a critical asparagine residue in the second TM helix of PhoQ. Replacement of this Asn202 with a variety of hydrophobic amino acids results in a protein that is blind to signal, fails to activate transcription of PhoQ-dependent genes, and abrogates transcription when coexpressed with wild-type PhoQ. Analysis of other two-component kinase sequences indicated that many such proteins contain similarly conserved polar residues, and the structure of one such domain shows a polar residue proximal to an extended cavity near the center of the TM bundle. We therefore examined the role of Asn202 in PhoQ. Our analysis indicated that its kinase function is dependent on the polarity of Asn202, rather than its precise structure or position in the TM region; it can be displaced up or down one turn of TM helix 2, or even moved to the adjacent TM helix 1. The presence of polar TM amino acids among many diverse sensor kinases suggest a widespread mechanism of two-component signal transduction; we speculate that they might stabilize underpacked water-containing cavities that can accommodate conformational changes required for switching from phosphatase to kinase-competent conformations.
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Yagasaki J, Suzuki D, Ihara K, Inoue K, Kikukawa T, Sakai M, Fujii M, Homma M, Kandori H, Sudo Y. Spectroscopic studies of a sensory rhodopsin I homologue from the archaeon Haloarcula vallismortis. Biochemistry 2010; 49:1183-90. [PMID: 20067303 DOI: 10.1021/bi901824a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sensory rhodopsin I (SRI) functions as a dual receptor regulating both negative and positive phototaxis. It transmits light signals through changes in protein-protein interactions with its transducer protein, HtrI. The phototaxis function of Halobacterium salinarum SRI (HsSRI) has been well characterized using genetic and molecular techniques, whereas that of Salinibacter ruber SRI (SrSRI) has not. SrSRI has the advantage of high protein stability compared with HsSRI and, therefore, provided new information about structural changes and Cl(-) binding of SRI. However, nothing is known about the functional role of SrSRI in phototaxis behavior. In this study, we expressed a SRI homologue from the archaeon Haloarcula vallismortis (HvSRI) as a recombinant protein which uses all-trans-retinal as a chromophore. Functionally important residues of HsSRI are completely conserved in HvSRI (unlike in SrSRI), and HvSRI is extremely stable in buffers without Cl(-). Taking advantage of the high stability, we characterized the photochemical properties of HvSRI under acidic and basic conditions and observed the effects of Cl(-) on the protein under both conditions. Fourier transform infrared results revealed that the structural changes in HvSRI were quite similar to those in HsSRI and SrSRI. Thus, HvSRI can become a useful protein model for improving our understanding of the molecular mechanism of the dual photosensing by SRI.
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Affiliation(s)
- Jin Yagasaki
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
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Streif S, Oesterhelt D, Marwan W. A predictive computational model of the kinetic mechanism of stimulus-induced transducer methylation and feedback regulation through CheY in archaeal phototaxis and chemotaxis. BMC SYSTEMS BIOLOGY 2010; 4:27. [PMID: 20298562 PMCID: PMC2857822 DOI: 10.1186/1752-0509-4-27] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 03/18/2010] [Indexed: 11/10/2022]
Abstract
Background Photo- and chemotaxis of the archaeon Halobacterium salinarum is based on the control of flagellar motor switching through stimulus-specific methyl-accepting transducer proteins that relay the sensory input signal to a two-component system. Certain members of the transducer family function as receptor proteins by directly sensing specific chemical or physical stimuli. Others interact with specific receptor proteins like the phototaxis photoreceptors sensory rhodopsin I and II, or require specific binding proteins as for example some chemotaxis transducers. Receptor activation by light or a change in receptor occupancy by chemical stimuli results in reversible methylation of glutamate residues of the transducer proteins. Both, methylation and demethylation reactions are involved in sensory adaptation and are modulated by the response regulator CheY. Results By mathematical modeling we infer the kinetic mechanisms of stimulus-induced transducer methylation and adaptation. The model (deterministic and in the form of ordinary differential equations) correctly predicts experimentally observed transducer demethylation (as detected by released methanol) in response to attractant and repellent stimuli of wildtype cells, a cheY deletion mutant, and a mutant in which the stimulated transducer species is methylation-deficient. Conclusions We provide a kinetic model for signal processing in photo- and chemotaxis in the archaeon H. salinarum suggesting an essential role of receptor cooperativity, antagonistic reversible methylation, and a CheY-dependent feedback on transducer demethylation.
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Affiliation(s)
- Stefan Streif
- Max Planck Institute for Dynamics of Complex Technical Systems, Molecular Network Analysis Group, Sandtorstr, 1, Magdeburg, Germany.
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Nishikata K, Fuchigami S, Ikeguchi M, Kidera A. Molecular modeling of the HAMP domain of sensory rhodopsin II transducer from Natronomonas pharaonis. Biophysics (Nagoya-shi) 2010; 6:27-36. [PMID: 27857583 PMCID: PMC5036668 DOI: 10.2142/biophysics.6.27] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 02/16/2010] [Indexed: 12/02/2022] Open
Abstract
The halobacterial transducer of sensory rhodopsin II (HtrII) is a photosignal transducer associated with phototaxis in extreme halophiles. The HAMP domain, a linker domain in HtrII, is considered to play an important role in transferring the signal from the membrane to the cytoplasmic region, although its structure in the complex remains undetermined. To establish the structural basis for understanding the mechanism of signal transduction, we present an atomic model of the structure of the N-terminal HAMP domain from Natronomonas pharaonis (HtrII: 84–136), based on molecular dynamics (MD) simulations. The model was built by homology modeling using the NMR structure of Af1503 from Archaeoglobus fulgidus as a template. The HAMP domains of Af1503 and HtrII were stable during MD simulations over 100 ns. Quantitative analyses of inter-helical packing indicated that the Af1503 HAMP domain stably maintained unusual knobs-to-knobs packing, as observed in the NMR structure, while the bulky side-chains of HtrII shifted the packing state to canonical knobs-into-holes. The role of the connector loop in maintaining structural stability was also discussed using MD simulations of loop deletion mutants.
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Affiliation(s)
- Koro Nishikata
- Graduate School of Nanobioscience, Yokohama City University, Yokohama 230-0045, Japan
| | - Sotaro Fuchigami
- Graduate School of Nanobioscience, Yokohama City University, Yokohama 230-0045, Japan
| | - Mitsunori Ikeguchi
- Graduate School of Nanobioscience, Yokohama City University, Yokohama 230-0045, Japan
| | - Akinori Kidera
- Graduate School of Nanobioscience, Yokohama City University, Yokohama 230-0045, Japan; Research Program for Computational Science, RIKEN, Wako 351-0198, Japan
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Dai G, Ohno Y, Ikeda Y, Tamogami J, Kikukawa T, Kamo N, Iwasa T. Photoreaction Cycle of Phoborhodopsin (Sensory Rhodopsin II) from Halobacterium salinarum Expressed in Escherichia coli. Photochem Photobiol 2010; 86:571-9. [DOI: 10.1111/j.1751-1097.2009.00687.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Möglich A, Yang X, Ayers RA, Moffat K. Structure and function of plant photoreceptors. ANNUAL REVIEW OF PLANT BIOLOGY 2010; 61:21-47. [PMID: 20192744 DOI: 10.1146/annurev-arplant-042809-112259] [Citation(s) in RCA: 334] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Signaling photoreceptors use the information contained in the absorption of a photon to modulate biological activity in plants and a wide range of organisms. The fundamental-and as yet imperfectly answered-question is, how is this achieved at the molecular level? We adopt the perspective of biophysicists interested in light-dependent signal transduction in nature and the three-dimensional structures that underpin signaling. Six classes of photoreceptors are known: light-oxygen-voltage (LOV) sensors, xanthopsins, phytochromes, blue-light sensors using flavin adenine dinucleotide (BLUF), cryptochromes, and rhodopsins. All are water-soluble proteins except rhodopsins, which are integral membrane proteins; all are based on a modular architecture except cryptochromes and rhodopsins; and each displays a distinct, light-dependent chemical process based on the photochemistry of their nonprotein chromophore, such as isomerization about a double bond (xanthopsins, phytochromes, and rhodopsins), formation or rupture of a covalent bond (LOV sensors), or electron transfer (BLUF sensors and cryptochromes).
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Affiliation(s)
- Andreas Möglich
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, USA.
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Abstract
Phototaxis in the broadest sense means positive or negative displacement along a light gradient or vector. Prokaryotes most often use a biased random walk strategy, employing type I sensory rhodopsin photoreceptors and two-component signalling to regulate flagellar reversal. This strategy only allows phototaxis along steep light gradients, as found in microbial mats or sediments. Some filamentous cyanobacteria evolved the ability to steer towards a light vector. Even these cyanobacteria, however, can only navigate in two dimensions, gliding on a surface. In contrast, eukaryotes evolved the capacity to follow a light vector in three dimensions in open water. This strategy requires a polarized organism with a stable form, helical swimming with cilia and a shading or focusing body adjacent to a light sensor to allow for discrimination of light direction. Such arrangement and the ability of three-dimensional phototactic navigation evolved at least eight times independently in eukaryotes. The origin of three-dimensional phototaxis often followed a transition from a benthic to a pelagic lifestyle and the acquisition of chloroplasts either via primary or secondary endosymbiosis. Based on our understanding of the mechanism of phototaxis in single-celled eukaryotes and animal larvae, it is possible to define a series of elementary evolutionary steps, each of potential selective advantage, which can lead to pelagic phototactic navigation. We can conclude that it is relatively easy to evolve phototaxis once cell polarity, ciliary swimming and a stable cell shape are present.
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Affiliation(s)
- Gáspár Jékely
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany.
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39
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Sudo Y, Okada A, Suzuki D, Inoue K, Irieda H, Sakai M, Fujii M, Furutani Y, Kandori H, Homma M. Characterization of a Signaling Complex Composed of Sensory Rhodopsin I and Its Cognate Transducer Protein from the Eubacterium Salinibacter ruber. Biochemistry 2009; 48:10136-45. [DOI: 10.1021/bi901338d] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yuki Sudo
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Akiko Okada
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Daisuke Suzuki
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Keiichi Inoue
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Hiroki Irieda
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Makoto Sakai
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Yuji Furutani
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Hideki Kandori
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
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40
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Verhoefen MK, Lenz MO, Amarie S, Klare JP, Tittor J, Oesterhelt D, Engelhard M, Wachtveitl J. Primary Reaction of Sensory Rhodopsin II Mutant D75N and the Influence of Azide. Biochemistry 2009; 48:9677-83. [DOI: 10.1021/bi901197c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mirka-Kristin Verhoefen
- Institute of Physical and Theoretical Chemistry, Institute of Biophysics, Johann Wolfgang Goethe-University Frankfurt, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany
| | - Martin O. Lenz
- Institute of Physical and Theoretical Chemistry, Institute of Biophysics, Johann Wolfgang Goethe-University Frankfurt, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany
| | - Sergiu Amarie
- Institute of Physical and Theoretical Chemistry, Institute of Biophysics, Johann Wolfgang Goethe-University Frankfurt, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany
| | - Johann P. Klare
- Max-Planck-Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44139 Dortmund, Germany
| | - Jörg Tittor
- Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Dieter Oesterhelt
- Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Martin Engelhard
- Max-Planck-Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44139 Dortmund, Germany
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Institute of Biophysics, Johann Wolfgang Goethe-University Frankfurt, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany
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Bergo VB, Spudich EN, Spudich JL, Rothschild KJ. Active water in protein-protein communication within the membrane: the case of SRII-HtrII signal relay. Biochemistry 2009; 48:811-3. [PMID: 19187030 DOI: 10.1021/bi802180a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We detect internal water molecules in a membrane-embedded receptor-transducer complex and demonstrate water structure changes during formation of the signaling state. Time-resolved FTIR spectroscopy reveals stimulus-induced repositioning of one or more structurally active water molecules to a significantly more hydrophobic environment in the signaling state of the sensory rhodopsin II (SRII)-transducer (HtrII) complex. These waters, distinct from bound water molecules within the SRII receptor, appear to be in the middle of the transmembrane interface region near the Tyr199(SRII)-Asn74(HtrII) hydrogen bond. We conclude that water potentially plays an important role in the SRII --> HtrII signal transfer mechanism in the membrane's hydrophobic core.
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Affiliation(s)
- Vladislav B Bergo
- Department of Physics, Molecular Biophysics Laboratory, and Center for Photonics, Boston University, Boston, Massachusetts 02215, USA
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42
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Abstract
Microorganisms have various mechanisms at their disposal to react to (changes in) their ambient light climate (i.e., intensity, color, direction, and degree of polarization). Of these, one of the best studied mechanisms is the process of phototaxis. This process can be described as a behavioral migration-response of an organism toward a change in illumination regime. In this chapter we discuss three of these migration responses, based on swimming, swarming, and twitching motility, respectively. Swimming motility has been studied using a wide range of techniques, usually microscopy based. We present a detailed description of the assays used to study phototaxis in liquid cultures of the phototrophic organisms Halobacterium salinarum, Halorhodospira halophila, and Rhodobacter sphaeroides and briefly describe the molecular basis of these responses. Swarming and twitching motility are processes taking place at the interface between a solid phase and a liquid or gas phase. Although assays to study these processes are relatively straightforward, they are accompanied by technical complications, which we describe. Furthermore, we discuss the molecular processes underlying these forms of motility in Rhodocista centenaria and Synechocystis PCC6803. Recently, it has become clear that also chemotrophic organisms contain photoreceptor proteins that allow them to respond to their ambient light climate. Surprisingly, light-modulated motility responses can also be observed in the chemotrophic organisms Escherichia coli and Acinetobacter calcoaceticus. In the light-modulated surface migration not only "che-like" signal transduction reactions may play a role, but in addition processes as modulation of gene expression and even intermediary metabolism.
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Affiliation(s)
- Wouter D Hoff
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA
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43
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Suzuki D, Sudo Y, Furutani Y, Takahashi H, Homma M, Kandori H. Structural Changes of Salinibacter Sensory Rhodopsin I upon Formation of the K and M Photointermediates. Biochemistry 2008; 47:12750-9. [DOI: 10.1021/bi801358b] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daisuke Suzuki
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
| | - Yuki Sudo
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
| | - Yuji Furutani
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
| | - Hazuki Takahashi
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
| | - Hideki Kandori
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
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Abstract
Sensory rhodopsin I (SRI) in Halobacterium salinarum acts as a receptor for single-quantum attractant and two-quantum repellent phototaxis, transmitting light stimuli via its bound transducer HtrI. Signal-inverting mutations in the SRI-HtrI complex reverse the single-quantum response from attractant to repellent. Fast intramolecular charge movements reported here reveal that the unphotolyzed SRI-HtrI complex exists in two conformational states, which differ by their connection of the retinylidene Schiff base in the SRI photoactive site to inner or outer half-channels. In single-quantum photochemical reactions, the conformer with the Schiff base connected to the cytoplasmic (CP) half-channel generates an attractant signal, whereas the conformer with the Schiff base connected to the extracellular (EC) half-channel generates a repellent signal. In the wild-type complex the conformer equilibrium is poised strongly in favor of that with CP-accessible Schiff base. Signal-inverting mutations shift the equilibrium in favor of the EC-accessible Schiff base form, and suppressor mutations shift the equilibrium back toward the CP-accessible Schiff base form, restoring the wild-type phenotype. Our data show that the sign of the behavioral response directly correlates with the state of the connectivity switch, not with the direction of proton movements or changes in acceptor pK(a). These findings identify a shared fundamental process in the mechanisms of transport and signaling by the rhodopsin family. Furthermore, the effects of mutations in the HtrI subunit of the complex on SRI Schiff base connectivity indicate that the two proteins are tightly coupled to form a single unit that undergoes a concerted conformational transition.
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Hisatomi O, Iwasa T, Kataoka M, Ebrey T. Introduction to the Symposium-in-Print on Photoreceptors and Signal Transduction in Honor of Professor Fumio Tokunaga. Photochem Photobiol 2008. [DOI: 10.1111/j.1751-1097.2008.00391.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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46
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Genomics and functional genomics with haloarchaea. Arch Microbiol 2008; 190:197-215. [PMID: 18493745 DOI: 10.1007/s00203-008-0376-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 04/08/2008] [Accepted: 04/20/2008] [Indexed: 10/22/2022]
Abstract
The first haloarchaeal genome was published in 2000 and today five genome sequences are available. Transcriptome and proteome analyses have been established for two and three haloarchaeal species, respectively, and more than 20 studies using these functional genomic approaches have been published in the last two years. These studies gave global overviews of metabolic regulation (aerobic and anaerobic respiration, phototrophy, carbon source usage), stress response (UV, X-rays, transition metals, osmotic and temperature stress), cell cycle-dependent transcript level regulation, and transcript half-lives. The only translatome analysis available for any prokaryotic species revealed that 10 and 20% of all transcripts are translationally regulated in Haloferax volcanii and Halobacterium salinarum, respectively. Very effective methods for the construction of in frame deletion mutants have been established recently for haloarchaea and are intensively used to unravel the biological roles of genes in this group. Bioinformatic analyses include both cross-genome comparisons as well as integration of genomic data with experimental results. The first systems biology approaches have been performed that used experimental data to construct predictive models of gene expression and metabolism, respectively. In this contribution the current status of genomics, functional genomics, and molecular genetics of haloarchaea is summarized and selected examples are discussed.
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