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Ritz S, Hulko M, Zerfass C, May S, Hospach I, Krasteva N, Nelles G, Sinner EK. Cell-free expression of a mammalian olfactory receptor and unidirectional insertion into small unilamellar vesicles (SUVs). Biochimie 2013; 95:1909-16. [PMID: 23816872 DOI: 10.1016/j.biochi.2013.06.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 06/20/2013] [Indexed: 01/29/2023]
Abstract
Although the identification of the multigene family encoding mammalian olfactory receptors were identified more than 20 years ago, we are far from understanding olfactory perception because of the difficulties in functional expression of these receptors in heterologous cell systems. Cell-free (CF) or in vitro expression systems offer an elegant alternative route to cell based protein expression, as the functional expression of membrane proteins can be directly achieved from the genetic template without the need of cell cultivation and protein isolation. Here we investigated in detail the cell-free expression and membrane insertion of the olfactory receptor OR5 in dependence of different experimental conditions like probing different origins of the cell-free expression system (from bacteria, via plants and insects toward mammalian system) and lipid composition of the respective extracts. We provided substantial biochemical indications by radioactive labeling based on [(35)S]-methionine, followed by proteolytic digestion, and we found that the insertion of the olfactory receptor OR5 into liposomes resulted in an unidirectional orientation with the binding side exposed into the aqueous space, resembling the native orientation in the cilia of the olfactory neurons. We report the different results in synthesis capacity for the different in vitro systems employed as we like to demonstrate the first in vitro kit toward and ex situ and ex vivo odorant receptor array.
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Affiliation(s)
- Sandra Ritz
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany.
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52
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Wang M, Ge B, Li R, Wang X, Lao J, Huang F. Milligram production and biological activity characterization of the human chemokine receptor CCR3. PLoS One 2013; 8:e65500. [PMID: 23755240 PMCID: PMC3670934 DOI: 10.1371/journal.pone.0065500] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 04/26/2013] [Indexed: 01/05/2023] Open
Abstract
Human chemokine receptor CCR3 (hCCR3) belongs to the G protein-coupled receptors (GPCRs) superfamily of membrane proteins and plays major roles in allergic diseases and angiogenesis. In order to study the structural and functional mechanism of hCCR3, it is essential to produce pure protein with biological functions on a milligram scale. Here we report the expression of hCCR3 gene in a tetracycline-inducible stable mammalian cell line. A cell clone with high hCCR3 expression was selected from 46 stably transfected cell clones and from this cell line pure hCCR3 on a milligram scale was obtained after two-step purification. Circular dichroism spectrum with a characteristic shape and magnitude for α-helix indicated proper folding of hCCR3 after purification. The biological activity of purified hCCR3 was verified by its high binding affinity with its endogenous ligands CCL11 and CCL24, with K D in the range of 10(-8) M to 10(-6) M.
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Affiliation(s)
- Mingqing Wang
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
| | - Baosheng Ge
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
| | - Renmin Li
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, PR China
| | - Xiaoqiang Wang
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
| | - Jun Lao
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
| | - Fang Huang
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
- Center for Bioengineering and Biotechnology, China University of Petroleum (Huadong), Qingdao, Shandong, PR China
- * E-mail:
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Hartmann C, Triller A, Spehr M, Dittrich R, Hatt H, Buettner A. Sperm-Activating Odorous Substances in Human Follicular Fluid and Vaginal Secretion: Identification by Gas Chromatography-Olfactometry and Ca2+Imaging. Chempluschem 2013; 78:695-702. [DOI: 10.1002/cplu.201300008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Revised: 04/24/2013] [Indexed: 01/03/2023]
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Decreased Perception of Bourgeonal May Be Linked to Male Idiopathic Infertility. Chem Senses 2013; 38:439-45. [DOI: 10.1093/chemse/bjt009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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55
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Basu D, Castellano JM, Thomas N, Mishra RK. Cell-free protein synthesis and purification of human dopamine D2 receptor long isoform. Biotechnol Prog 2013; 29:601-8. [PMID: 23424095 DOI: 10.1002/btpr.1706] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 02/06/2013] [Indexed: 02/06/2023]
Abstract
The human dopamine D2 receptor long isoform (D2L) has significant implications in neurological and neuropsychiatric disorders such as Parkinson's disease and schizophrenia. Detailed structural knowledge of this receptor is limited owing to its highly hydrophobic nature, which leads to protein aggregation and host toxicity when expressed in cellular systems. The newly emerging field of cell-free protein expression presents numerous advantages to overcome these challenges. This system utilizes protein synthesis machinery and exogenous DNA to synthesize functional proteins outside of intact cells. This study utilizes two different cell-free systems for the synthesis of human dopamine D2L receptor. These include the Escherichia coli lysate-based system and the wheat-germ lysate-based system. The bacterial cell-free method used pET 100/D-TOPO vector to synthesize hexa-histidine-tagged D2L receptor using a dialysis bag system; the resulting protein was purified using nickel-nitrilotriacetic acid affinity resin. The wheat germ system used pEU-glutathione-S-transferase (GST) vector to synthesize GST-tagged D2L receptor using a bilayer translation method; the resulting protein was purified using a GST affinity resin. The presence and binding capacity of the synthesized D2L receptor was confirmed by immunoblotting and radioligand competition assays, respectively. Additionally, in-gel protein sequencing via Nano LC-MS/MS was used to confirm protein synthesis via the wheat germ system. The results showed both systems to synthesize microgram quantities of the receptor. Improved expression of this highly challenging protein can improve research and understanding of the human dopamine D2L receptor.
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Affiliation(s)
- Dipannita Basu
- Dept. of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada, L8N 3Z5
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56
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Ottaviano G, Zuccarello D, Menegazzo M, Perilli L, Marioni G, Frigo AC, Staffieri A, Foresta C. Human olfactory sensitivity for bourgeonal and male infertility: a preliminary investigation. Eur Arch Otorhinolaryngol 2013; 270:3079-86. [PMID: 23525651 DOI: 10.1007/s00405-013-2441-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 03/08/2013] [Indexed: 10/27/2022]
Abstract
Olfactory receptor (OR) expression is also present in the sperm cells and could mediate sperm chemotaxis. OR1D2 was the first OR expressed in the testis demonstrated to be involved in chemotaxis and to be expressed also in the nose with a similar behavior. Bourgeonal is the OR1D2 most potent known agonist. Infertility affects ~15 % of couples in western countries and sometimes it is unexplained. This pilot study compared the bourgeonal olfactory thresholds, the ability of sperm to sense the bourgeonal and the frequency of 13 single nucleotide polymorphisms (SNPs) of OR1D2 gene in nine males suffering of unexplained infertility with a control group of 15 healthy males. The mean olfactory threshold for bourgeonal was statistically different between the study group (10.5 ± 3.7; median 12.3) and the control group (14.0 ± 2.8; median 15.5) (p = 0.006). Statistical analysis showed a significantly higher percentage of spermatozoa that migrated toward the capillaries filled with bourgeonal in the control group compared to the study group (p < 0.0001). Sperm migration was equally inhibited in both groups of subjects when, together with bourgeonal, capillaries were filled with undecanal, a strong bourgeonal inhibitor (p = 0.42). The 13 SNPs of OR1D2 revealed a statistically significant difference for allele and genotype frequency of rs769423 in study group versus control group (p = 0.02). The present preliminary study seems to confirm the important role of OR1D2 both in nose and spermatozoa and may explain the idiopathic infertility of the study group. Further studies on larger series are mandatory to confirm our preliminary evidence.
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Affiliation(s)
- G Ottaviano
- Department of Neurosciences, Otolaryngology Section, University of Padova, Via Giustiniani 2, 35128, Padua, Italy,
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57
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Expression and purification of functional human mu opioid receptor from E.coli. PLoS One 2013; 8:e56500. [PMID: 23437147 PMCID: PMC3578875 DOI: 10.1371/journal.pone.0056500] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Accepted: 01/10/2013] [Indexed: 12/17/2022] Open
Abstract
N-terminally his-tagged human mu opioid receptor, a G protein-coupled receptor was produced in E.coli employing synthetic codon-usage optimized constructs. The receptor was expressed in inclusion bodies and membrane-inserted in different E.coli strains. By optimizing the expression conditions the expression level for the membrane-integrated receptor was raised to 0.3–0.5 mg per liter of culture. Milligram quantities of receptor could be enriched by affinity chromatography from IPTG induced cultures grown at 18°C. By size exclusion chromatography the protein fraction with the fraction of alpha-helical secondary structure expected for a 7-TM receptor was isolated, by CD-spectroscopy an alpha-helical content of ca. 45% was found for protein solubilised in the detergent Fos-12. Receptor in Fos-12 micelles was shown to bind endomorphin-1 with a KD of 61 nM. A final yield of 0.17 mg functional protein per liter of culture was obtained.
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58
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Liu J, Chen C, Ge B, Lu J, Cui Z. A novel membrane based process to isolate recombinant human chemokine receptor CCR3 produced in Escherichia coli. J Memb Sci 2013. [DOI: 10.1016/j.memsci.2012.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Du L, Wu C, Liu Q, Huang L, Wang P. Recent advances in olfactory receptor-based biosensors. Biosens Bioelectron 2012; 42:570-80. [PMID: 23261691 DOI: 10.1016/j.bios.2012.09.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 08/20/2012] [Accepted: 09/02/2012] [Indexed: 12/30/2022]
Abstract
The biological olfactory system can recognize and discriminate thousands of volatile organic compounds (VOCs) with extremely high sensitivity and specificity. The most fundamental elements are olfactory receptors (ORs) in the cilia of olfactory sensory neurons (OSNs), which contribute greatly to the high-performance olfactory system. The excellent properties of ORs are generally recognized in the development of biomimetic OR-based biosensors. Over the past two decades, much work has been done in developing OR-based biosensors due to their promising potential in many applications. In this article, we will outline the latest advances of OR-based biosensors. Two current crucial issues in this field will be discussed, namely, the production methods and immobilization techniques of ORs. We will also elaborate on various OR-based biosensors and their latest developments. Finally, current research trends and future challenges in this field will be discussed.
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Affiliation(s)
- Liping Du
- Biosensor National Special Laboratory, Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China
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60
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Abstract
The number of structures of integral membrane proteins from higher eukaryotes is steadily increasing due to a number of innovative protein engineering and crystallization strategies devised over the last few years. However, it is sobering to reflect that these structures represent only a tiny proportion of the total number of membrane proteins encoded by a mammalian genome. In addition, the structures determined to date are of the most tractable membrane proteins, i.e., those that are expressed functionally and to high levels in yeast or in insect cells using the baculovirus expression system. However, some membrane proteins that are expressed inefficiently in these systems can be produced at sufficiently high levels in mammalian cells to allow structure determination. Mammalian expression systems are an under-used resource in structural biology and represent an effective way to produce fully functional membrane proteins for structural studies. This review will discuss examples of vertebrate membrane protein overexpression in mammalian cells using a variety of viral, constitutive or inducible expression systems.
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Affiliation(s)
- Juni Andréll
- MRC Laboratory of Molecular Biology, Cambridge, UK
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61
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Solov'yov IA, Chang PY, Schulten K. Vibrationally assisted electron transfer mechanism of olfaction: myth or reality? Phys Chem Chem Phys 2012; 14:13861-71. [PMID: 22899100 DOI: 10.1039/c2cp41436h] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Smell is a vital sense for animals. The mainstream explanation of smell is based on recognition of the odorant molecules through characteristics of their surface, e.g., shape, but certain experiments suggest that such recognition is complemented by recognition of vibrational modes. According to this suggestion an olfactory receptor is activated by electron transfer assisted through odorant vibrational excitation. The hundreds to thousands of different olfactory receptors in an animal recognize odorants over a discriminant landscape with surface properties and vibrational frequencies as the two major dimensions. In the present paper we introduce the vibrationally assisted mechanism of olfaction and demonstrate for several odorants that, indeed, a strong enhancement of an electron tunneling rate due to odorant vibrations can arise. We discuss in this regard the influence of odorant deuteration and explain, thereby, recent experiments performed on Drosophila melanogaster. Our demonstration is based on known physical properties of biological electron transfer and on ab initio calculations on odorants carried out for the purpose of the present study. We identify a range of physical characteristics which olfactory receptors and odorants must obey for the vibrationally assisted electron transfer mechanism to function. We argue that the stated characteristics are feasible for realistic olfactory receptors, noting, though, that the receptor structure presently is still unknown, but can be studied through homology modeling.
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Affiliation(s)
- Ilia A Solov'yov
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave., Urbana, Illinois 61801, USA.
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62
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Ohsfeldt E, Huang SH, Baycin-Hizal D, Kristoffersen L, Le TMT, Li E, Hristova K, Betenbaugh MJ. Increased expression of the integral membrane proteins EGFR and FGFR3 in anti-apoptotic Chinese hamster ovary cell lines. Biotechnol Appl Biochem 2012; 59:155-62. [PMID: 23586824 DOI: 10.1002/bab.1000] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 01/04/2012] [Indexed: 01/12/2023]
Abstract
Membrane proteins such as receptor tyrosine kinases (RTKs) have a vital role in many cellular functions, making them potential targets for therapeutic research. In this study, we investigated the coexpression of the anti-apoptosis gene Bcl-x(L) with model membrane proteins as a means of increasing membrane protein expression in mammalian cells. Chinese hamster ovary (CHO) cells expressing heterologous Bcl-x(L) and wild-type CHO cells were transfected with either epidermal growth factor receptor or fibroblast growth factor receptor 3. The CHO-Bcl-x(L) cell lines showed increased expression of both RTK proteins as compared with the wild-type CHO cell lines in transient expression analysis, as detected by Western blot and flow cytometry after 15 days of antibiotic selection in stable expression pools. Increased expression was also seen in clonal isolates from the CHO-Bcl-x(L) cell lines, whereas the clonal cell line expression was minimal in wild-type CHO cell lines. Our results demonstrate that application of the anti-apoptosis gene Bcl-x(L) can increase expression of RTK proteins in CHO cells. This approach may be applied to improve stable expression of other membrane proteins in the future using mammalian cell lines with Bcl-x(L) or perhaps other anti-apoptotic genes.
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Affiliation(s)
- Erika Ohsfeldt
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA
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63
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Luo Z, Zhang S. Designer nanomaterials using chiral self-assembling peptide systems and their emerging benefit for society. Chem Soc Rev 2012; 41:4736-54. [DOI: 10.1039/c2cs15360b] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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64
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Corin K, Pick H, Baaske P, Cook BL, Duhr S, Wienken CJ, Braun D, Vogel H, Zhang S. Insertion of T4-lysozyme (T4L) can be a useful tool for studying olfactory-related GPCRs. MOLECULAR BIOSYSTEMS 2012; 8:1750-9. [DOI: 10.1039/c2mb05495g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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65
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66
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Corin K, Baaske P, Geissler S, Wienken CJ, Duhr S, Braun D, Zhang S. Structure and function analyses of the purified GPCR human vomeronasal type 1 receptor 1. Sci Rep 2011; 1:172. [PMID: 22355687 PMCID: PMC3240957 DOI: 10.1038/srep00172] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 10/25/2011] [Indexed: 12/31/2022] Open
Abstract
The vomeronasal system is one of several fine-tuned scent-detecting signaling systems in mammals. However, despite significant efforts, how these receptors detect scent remains an enigma. One reason is the lack of sufficient purified receptors to perform detailed biochemical, biophysical and structural analyses. Here we report the ability to express and purify milligrams of purified, functional human vomeronasal receptor hVN1R1. Circular dichroism showed that purified hVN1R1 had an alpha-helical structure, similar to that of other GPCRs. Microscale thermophoresis showed that hVN1R1 bound its known ligand myrtenal with an EC(50) approximately 1 µM. This expression system can enable structural and functional analyses towards understanding how mammalian scent detection works.
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Affiliation(s)
- Karolina Corin
- Center for Biomedical Engineering, NE47-379, Massachusetts Institute
of Technology, 77 Massachusetts Avenue, Cambridge,
MA 02139-4307, USA
| | - Philipp Baaske
- NanoTemper Technologies GmbH, Amalienstrasse
54, 80799 München, Germany
| | - Sandra Geissler
- NanoTemper Technologies GmbH, Amalienstrasse
54, 80799 München, Germany
| | - Christoph J. Wienken
- Systems Biophysics, Functional Nanosystems, Department of Physics,
Ludwig-Maximilians University München, Amalienstrasse 54,
80799 München, Germany
| | - Stefan Duhr
- NanoTemper Technologies GmbH, Amalienstrasse
54, 80799 München, Germany
| | - Dieter Braun
- Systems Biophysics, Functional Nanosystems, Department of Physics,
Ludwig-Maximilians University München, Amalienstrasse 54,
80799 München, Germany
| | - Shuguang Zhang
- Center for Biomedical Engineering, NE47-379, Massachusetts Institute
of Technology, 77 Massachusetts Avenue, Cambridge,
MA 02139-4307, USA
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67
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Corin K, Baaske P, Ravel DB, Song J, Brown E, Wang X, Wienken CJ, Jerabek-Willemsen M, Duhr S, Luo Y, Braun D, Zhang S. Designer lipid-like peptides: a class of detergents for studying functional olfactory receptors using commercial cell-free systems. PLoS One 2011; 6:e25067. [PMID: 22132066 PMCID: PMC3223156 DOI: 10.1371/journal.pone.0025067] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 08/26/2011] [Indexed: 01/18/2023] Open
Abstract
A crucial bottleneck in membrane protein studies, particularly G-protein coupled receptors, is the notorious difficulty of finding an optimal detergent that can solubilize them and maintain their stability and function. Here we report rapid production of 12 unique mammalian olfactory receptors using short designer lipid-like peptides as detergents. The peptides were able to solubilize and stabilize each receptor. Circular dichroism showed that the purified olfactory receptors had alpha-helical secondary structures. Microscale thermophoresis suggested that the receptors were functional and bound their odorants. Blot intensity measurements indicated that milligram quantities of each olfactory receptor could be produced with at least one peptide detergent. The peptide detergents' capability was comparable to that of the detergent Brij-35. The ability of 10 peptide detergents to functionally solubilize 12 olfactory receptors demonstrates their usefulness as a new class of detergents for olfactory receptors, and possibly other G-protein coupled receptors and membrane proteins.
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Affiliation(s)
- Karolina Corin
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | | | - Deepali B. Ravel
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Junyao Song
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Emily Brown
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Xiaoqiang Wang
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Center for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao, Shandong, China
| | - Christoph J. Wienken
- Systems Biophysics, Functional Nanosystems, Ludwig-Maximilians University Munich, München, Germany
| | - Moran Jerabek-Willemsen
- Systems Biophysics, Functional Nanosystems, Ludwig-Maximilians University Munich, München, Germany
| | - Stefan Duhr
- NanoTemper Technologies GmbH, München, Germany
| | - Yuan Luo
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, United States of America
| | - Dieter Braun
- Systems Biophysics, Functional Nanosystems, Ludwig-Maximilians University Munich, München, Germany
| | - Shuguang Zhang
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
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68
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Corin K, Baaske P, Ravel DB, Song J, Brown E, Wang X, Geissler S, Wienken CJ, Jerabek-Willemsen M, Duhr S, Braun D, Zhang S. A robust and rapid method of producing soluble, stable, and functional G-protein coupled receptors. PLoS One 2011; 6:e23036. [PMID: 22039398 PMCID: PMC3201940 DOI: 10.1371/journal.pone.0023036] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Accepted: 07/04/2011] [Indexed: 11/20/2022] Open
Abstract
Membrane proteins, particularly G-protein coupled receptors (GPCRs), are notoriously difficult to express. Using commercial E. coli cell-free systems with the detergent Brij-35, we could rapidly produce milligram quantities of 13 unique GPCRs. Immunoaffinity purification yielded receptors at >90% purity. Secondary structure analysis using circular dichroism indicated that the purified receptors were properly folded. Microscale thermophoresis, a novel label-free and surface-free detection technique that uses thermal gradients, showed that these receptors bound their ligands. The secondary structure and ligand-binding results from cell-free produced proteins were comparable to those expressed and purified from HEK293 cells. Our study demonstrates that cell-free protein production using commercially available kits and optimal detergents is a robust technology that can be used to produce sufficient GPCRs for biochemical, structural, and functional analyses. This robust and simple method may further stimulate others to study the structure and function of membrane proteins.
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Affiliation(s)
- Karolina Corin
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | | | - Deepali B. Ravel
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Junyao Song
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Emily Brown
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Xiaoqiang Wang
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Center for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao, Shandong, People's Republic of China
| | | | - Christoph J. Wienken
- Systems Biophysics, Functional Nanosystems, Ludwig-Maximilians University München, München, Germany
| | | | - Stefan Duhr
- NanoTemper Technologies GmbH, München, Germany
| | - Dieter Braun
- Systems Biophysics, Functional Nanosystems, Ludwig-Maximilians University München, München, Germany
| | - Shuguang Zhang
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
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69
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Wang X, Corin K, Rich C, Zhang S. Study of two G-protein coupled receptor variants of human trace amine-associated receptor 5. Sci Rep 2011; 1:102. [PMID: 22355620 PMCID: PMC3216587 DOI: 10.1038/srep00102] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/18/2011] [Indexed: 01/01/2023] Open
Abstract
Here we report the study of two bioengineered variants of human trace amine-associated receptor 5 (hTAAR5) that were expressed in stable tetracycline-inducible HEK293S cell lines. A systematic detergent screen showed that fos-choline-14 was the optimal detergent to solubilize and subsequently purify the receptors. Milligram quantities of both hTAAR5 variants were purified to near homogeneity using immunoaffinity chromatography followed by gel filtration. Circular dichroism showed that the purified receptors had helical secondary structures, indicating that they were properly folded. The purified receptors are not only suitable for functional analyses, but also for subsequent crystallization trials. To our knowledge, this is the first mammalian TAAR that has been heterologously expressed and purified. Our study will likely stimulate in the development of therapeutic drug targets for TAAR-associated diseases, as well as fabrication of TAAR-based sensing devices.
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Affiliation(s)
- Xiaoqiang Wang
- Center for Biomedical Engineering NE47-379, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
- Center for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao, Shandong 266555, China
| | - Karolina Corin
- Center for Biomedical Engineering NE47-379, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
| | - Cyrus Rich
- Center for Biomedical Engineering NE47-379, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
| | - Shuguang Zhang
- Center for Biomedical Engineering NE47-379, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
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Wang X, Zhang S. Production of a bioengineered G-protein coupled receptor of human formyl peptide receptor 3. PLoS One 2011; 6:e23076. [PMID: 21853070 PMCID: PMC3154916 DOI: 10.1371/journal.pone.0023076] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 07/05/2011] [Indexed: 01/07/2023] Open
Abstract
G-protein coupled receptors (GPCRs) participate in a wide range of vital regulations of our physiological actions. They are also of pharmaceutical importance and have become many therapeutic targets for a number of disorders and diseases. Purified GPCR-based approaches including structural study and novel biophysical and biochemical function analyses are increasingly being used in GPCR-directed drug discovery. Before these approaches become routine, however, several hurdles need to be overcome; they include overexpression, solubilization, and purification of large quantities of functional and stable receptors on a regular basis. Here we report milligram production of a human formyl peptide receptor 3 (FPR3). FPR3 comprises a functionally distinct GPCR subfamily that is involved in leukocyte chemotaxis and activation. The bioengineered FPR3 was overexpressed in stable tetracycline-inducible mammalian cell lines (HEK293S). After a systematic detergent screening, fos-choline-14 (FC-14) was selected for subsequent solubilization and purification processes. A two-step purification method, immunoaffinity using anti-rho-tag monoclonal antibody 1D4 and gel filtration, was used to purify the receptors to near homogeneity. Immunofluorescence analysis showed that expressed FPR3 was predominantly displayed on cellular membrane. Secondary structural analysis using circular dichroism showed that the purified FPR3 receptor was correctly folded with >50% α-helix, which is similar to other known GPCR secondary structures. Our method can readily produce milligram quantities of human FPR3, which would facilitate in developing human FPR as therapeutic drug targets.
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Affiliation(s)
- Xiaoqiang Wang
- Center for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao, Shandong, China
| | - Shuguang Zhang
- Laboratory for Molecular Fabrication, Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
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71
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Dahoun T, Grasso L, Vogel H, Pick H. Recombinant Expression and Functional Characterization of Mouse Olfactory Receptor mOR256-17 in Mammalian Cells. Biochemistry 2011; 50:7228-35. [DOI: 10.1021/bi2008596] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thamani Dahoun
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Luigino Grasso
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Horst Vogel
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Horst Pick
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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72
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Wang X, Corin K, Baaske P, Wienken CJ, Jerabek-Willemsen M, Duhr S, Braun D, Zhang S. Peptide surfactants for cell-free production of functional G protein-coupled receptors. Proc Natl Acad Sci U S A 2011; 108:9049-54. [PMID: 21562213 PMCID: PMC3107261 DOI: 10.1073/pnas.1018185108] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two major bottlenecks in elucidating the structure and function of membrane proteins are the difficulty of producing large quantities of functional receptors, and stabilizing them for a sufficient period of time. Selecting the right surfactant is thus crucial. Here we report using peptide surfactants in commercial Escherichia coli cell-free systems to rapidly produce milligram quantities of soluble G protein-coupled receptors (GPCRs). These include the human formyl peptide receptor, human trace amine-associated receptor, and two olfactory receptors. The GPCRs expressed in the presence of the peptide surfactants were soluble and had α-helical secondary structures, suggesting that they were properly folded. Microscale thermophoresis measurements showed that one olfactory receptor expressed using peptide surfactants bound its known ligand heptanal (molecular weight 114.18). These short and simple peptide surfactants may be able to facilitate the rapid production of GPCRs, or even other membrane proteins, for structure and function studies.
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Affiliation(s)
- Xiaoqiang Wang
- Center for Biomedical Engineering NE47-379, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307
- Center for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao, Shandong 266555, People’s Republic of China
| | - Karolina Corin
- Center for Biomedical Engineering NE47-379, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307
| | - Philipp Baaske
- NanoTemper Technologies GmbH, Amalienstrasse 54, 80799 Munich, Germany; and
| | - Christoph J. Wienken
- Systems Biophysics, Functional Nanosystems, Department of Physics, Ludwig-Maximilians University Munich, Amalienstrasse 54, 80799 Munich, Germany
| | - Moran Jerabek-Willemsen
- Systems Biophysics, Functional Nanosystems, Department of Physics, Ludwig-Maximilians University Munich, Amalienstrasse 54, 80799 Munich, Germany
| | - Stefan Duhr
- NanoTemper Technologies GmbH, Amalienstrasse 54, 80799 Munich, Germany; and
| | - Dieter Braun
- Systems Biophysics, Functional Nanosystems, Department of Physics, Ludwig-Maximilians University Munich, Amalienstrasse 54, 80799 Munich, Germany
| | - Shuguang Zhang
- Center for Biomedical Engineering NE47-379, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307
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73
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Veitinger T, Riffell JR, Veitinger S, Nascimento JM, Triller A, Chandsawangbhuwana C, Schwane K, Geerts A, Wunder F, Berns MW, Neuhaus EM, Zimmer RK, Spehr M, Hatt H. Chemosensory Ca2+ dynamics correlate with diverse behavioral phenotypes in human sperm. J Biol Chem 2011; 286:17311-25. [PMID: 21454470 PMCID: PMC3089573 DOI: 10.1074/jbc.m110.211524] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Revised: 03/18/2011] [Indexed: 11/06/2022] Open
Abstract
In the female reproductive tract, mammalian sperm undergo a regulated sequence of prefusion changes that "prime" sperm for fertilization. Among the least understood of these complex processes are the molecular mechanisms that underlie sperm guidance by environmental chemical cues. A "hard-wired" Ca(2+) signaling strategy that orchestrates specific motility patterns according to given functional requirements is an emerging concept for regulation of sperm swimming behavior. The molecular players involved, the spatiotemporal characteristics of such motility-associated Ca(2+) dynamics, and the relation between a distinct Ca(2+) signaling pattern and a behavioral sperm phenotype, however, remain largely unclear. Here, we report the functional characterization of two human sperm chemoreceptors. Using complementary molecular, physiological, and behavioral approaches, we comparatively describe sperm Ca(2+) responses to specific agonists of these novel receptors and bourgeonal, a known sperm chemoattractant. We further show that individual receptor activation induces specific Ca(2+) signaling patterns with unique spatiotemporal dynamics. These distinct Ca(2+) dynamics are correlated to a set of stimulus-specific stereotyped behavioral responses that could play vital roles during various stages of prefusion sperm-egg chemical communication.
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Affiliation(s)
- Thomas Veitinger
- From the Department of Chemosensation, Institute for Biology II, Rheinisch-Westfaelische Technische Hochschule-Aachen University, 52074 Aachen, Germany
- the Department of Cellular Physiology, Ruhr-University, 44780 Bochum, Germany
| | - Jeffrey R. Riffell
- the Department of Neuroscience, University of Arizona, Tucson, Arizona 85721
| | - Sophie Veitinger
- From the Department of Chemosensation, Institute for Biology II, Rheinisch-Westfaelische Technische Hochschule-Aachen University, 52074 Aachen, Germany
- the Department of Cellular Physiology, Ruhr-University, 44780 Bochum, Germany
| | | | - Annika Triller
- the Department of Cellular Physiology, Ruhr-University, 44780 Bochum, Germany
| | | | - Katlen Schwane
- the Department of Cellular Physiology, Ruhr-University, 44780 Bochum, Germany
| | - Andreas Geerts
- the Bayer Schering Pharma AG Pharma Research Center, 42096 Wuppertal, Germany
| | - Frank Wunder
- the Bayer Schering Pharma AG Pharma Research Center, 42096 Wuppertal, Germany
| | - Michael W. Berns
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093-0412
- the Beckman Laser Institute, University of California, Irvine, California
| | - Eva M. Neuhaus
- the Charité-NeuroScience Research Center, 10117 Berlin, Germany, and
| | - Richard K. Zimmer
- the Department of Ecology and Evolutionary Biology, Neuroscience Program, and Brain Research Institute, UCLA, Los Angeles, California 90095-1606
| | - Marc Spehr
- From the Department of Chemosensation, Institute for Biology II, Rheinisch-Westfaelische Technische Hochschule-Aachen University, 52074 Aachen, Germany
| | - Hanns Hatt
- the Department of Cellular Physiology, Ruhr-University, 44780 Bochum, Germany
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74
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Baud O, Etter S, Spreafico M, Bordoli L, Schwede T, Vogel H, Pick H. The mouse eugenol odorant receptor: structural and functional plasticity of a broadly tuned odorant binding pocket. Biochemistry 2010; 50:843-53. [PMID: 21142015 DOI: 10.1021/bi1017396] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Molecular interactions of odorants with their olfactory receptors (ORs) are of central importance for the ability of the mammalian olfactory system to detect and discriminate a vast variety of odors with a limited set of receptors. How a particular OR binds and distinguishes different odorant molecules remains largely unknown on a structural basis. Here we investigated this question for the mouse eugenol receptor (mOR-EG). By screening a large odorant library, we discovered a wide range of chemical structures activating the receptor in heterologous mammalian cells. Potent agonists comprise (i) benzene, (ii) cyclohexane, or (iii) polycyclic structures substituted with alcohol, aldehyde, keto, ether, or esterified carboxylic groups. To detect those amino acids within the receptor that are in contact with a particular bound odorant molecule, we investigated how distinct mOR-EG point mutants were activated by the different odorant agonists found for the wild-type receptor. We identified 11 amino acids as a part of the receptor's ligand binding pocket. Molecular modeling predicted 10 of these residues in transmembrane helices TM3-TM6 and one in the extracellular loop between TM2 and TM3. These amino acids participate in odorant binding with variable importance depending on the type of odorant, revealing functional "fingerprints" of ligand-receptor interactions.
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Affiliation(s)
- Olivia Baud
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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75
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Glatz R, Bailey-Hill K. Mimicking nature's noses: from receptor deorphaning to olfactory biosensing. Prog Neurobiol 2010; 93:270-96. [PMID: 21130137 DOI: 10.1016/j.pneurobio.2010.11.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 11/09/2010] [Accepted: 11/22/2010] [Indexed: 12/21/2022]
Abstract
The way in which organisms detect specific volatile compounds within their environment, and the associated neural processing which produces perception and subsequent behavioural responses, have been of interest to scientists for decades. Initially, most olfaction research was conducted using electrophysiological techniques on whole animals. However, the discovery of genes encoding the family of human olfactory receptors (ORs) paved the way for the development of a range of cellular assays, primarily used to deorphan ORs from mammals and insects. These assays have greatly advanced our knowledge of the molecular basis of olfaction, however, while there is currently good agreement on vertebrate and nematode olfactory signalling cascades, debate still surrounds the signalling mechanisms in insects. The inherent specificity and sensitivity of ORs makes them prime candidates as biological detectors of volatile ligands within biosensor devices, which have many potential applications. In the previous decade, researchers have investigated various technologies for transducing OR:ligand interactions into a readable format and thereby produce an olfactory biosensor (or bioelectronic nose) that maintains the discriminating power of the ORs in vivo. Here we review and compare the molecular mechanisms of olfaction in vertebrates and invertebrates, and also summarise the assay technologies utilising sub-tissue level sensing elements (cells and cell extracts), which have been applied to OR deorphanization and biosensor research. Although there are currently no commercial, "field-ready" olfactory biosensors of the kind discussed here, there have been several technological proof-of-concept studies suggesting that we will see their emergence within the next decade.
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Affiliation(s)
- Richard Glatz
- South Australian Research and Development Institute (SARDI), Entomology, GPO Box 397, Adelaide 5001, Australia.
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76
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Leck KJ, Zhang S, Hauser CAE. Study of bioengineered zebra fish olfactory receptor 131-2: receptor purification and secondary structure analysis. PLoS One 2010; 5:e15027. [PMID: 21124770 PMCID: PMC2993934 DOI: 10.1371/journal.pone.0015027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 10/05/2010] [Indexed: 11/23/2022] Open
Abstract
How fishes are able to detect trace molecules in large bodies of water is not understood. It is plausible that they use olfactory receptors to detect water-soluble compounds. How the zebra fish Danio Rerio, an organism with only 98 functional olfactory receptors, is able to selectively detect and recognize numerous compounds in water remains a puzzling phenomenon. We are interested in studying the biochemical and molecular mechanisms of olfaction in fish. Here, we report on the study of a bioengineered zebra fish olfactory receptor OR131-2, affinity-purified from a HEK293S tetracycline-inducible system. This receptor was expressed and translocated to the cell plasma membrane as revealed by confocal microscopy. Circular dichroism spectroscopy showed that the purified zebra fish receptor folded into an α-helical structure, as observed for other G-protein coupled receptors (GPCRs). Our study shows that it is possible to produce viable quantities of the zebra fish olfactory receptor. This will not only enable detailed structural and functional analyses, but also aid in the design of biosensor devices in order to detect water-soluble metabolites or its intermediates, which are associated with human health.
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Affiliation(s)
- Kwong-Joo Leck
- Membrane Protein Nanobiotechnology Laboratory, Institute of Bioengineering and Nanotechnology, Singapore, Singapore
| | - Shuguang Zhang
- Membrane Protein Nanobiotechnology Laboratory, Institute of Bioengineering and Nanotechnology, Singapore, Singapore
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Charlotte A. E. Hauser
- Membrane Protein Nanobiotechnology Laboratory, Institute of Bioengineering and Nanotechnology, Singapore, Singapore
- * E-mail:
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77
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Tsitoura P, Andronopoulou E, Tsikou D, Agalou A, Papakonstantinou MP, Kotzia GA, Labropoulou V, Swevers L, Georgoussi Z, Iatrou K. Expression and membrane topology of Anopheles gambiae odorant receptors in lepidopteran insect cells. PLoS One 2010; 5:e15428. [PMID: 21082026 PMCID: PMC2972716 DOI: 10.1371/journal.pone.0015428] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 09/21/2010] [Indexed: 12/21/2022] Open
Abstract
A lepidopteran insect cell-based expression system has been employed to express three Anopheles gambiae odorant receptors (ORs), OR1 and OR2, which respond to components of human sweat, and OR7, the ortholog of Drosophila's OR83b, the heteromerization partner of all functional ORs in that system. With the aid of epitope tagging and specific antibodies, efficient expression of all ORs was demonstrated and intrinsic properties of the proteins were revealed. Moreover, analysis of the orientation of OR1 and OR2 on the cellular plasma membrane through the use of a novel ‘topology screen’ assay and FACS analysis demonstrates that, as was recently reported for the ORs in Drosophila melanogaster, mosquito ORs also have a topology different than their mammalian counterparts with their N-terminal ends located in the cytoplasm and their C-terminal ends facing outside the cell. These results set the stage for the production of mosquito ORs in quantities that should permit their detailed biochemical and structural characterization and the exploration of their functional properties.
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Affiliation(s)
- Panagiota Tsitoura
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Evi Andronopoulou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Daniela Tsikou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Adamantia Agalou
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Maria P. Papakonstantinou
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Georgia A. Kotzia
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Vassiliki Labropoulou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Zafiroula Georgoussi
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Kostas Iatrou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
- * E-mail:
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Efficient production and purification of functional bacteriorhodopsin with a wheat-germ cell-free system and a combination of Fos-choline and CHAPS detergents. Biochem Biophys Res Commun 2010; 400:638-42. [PMID: 20807510 DOI: 10.1016/j.bbrc.2010.08.119] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 08/26/2010] [Indexed: 11/20/2022]
Abstract
Cell-free translation is one potential approach to the production of functional transmembrane proteins. We have now examined various detergents as supplements to a wheat-germ cell-free system in order to optimize the production and subsequent purification of a functional model transmembrane protein, bacteriorhodopsin. We found that Fos-choline and CHAPS detergents counteracted each other's inhibitory effects on cell-free translation activity and thereby allowed the efficient production and subsequent purification of functional bacteriorhodopsin in high yield.
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79
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Cometto-Muñiz JE, Abraham MH. Odor detection by humans of lineal aliphatic aldehydes and helional as gauged by dose-response functions. Chem Senses 2010; 35:289-99. [PMID: 20190010 DOI: 10.1093/chemse/bjq018] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have measured concentration detection (i.e., psychometric) functions to determine the odor detectability of homologous aliphatic aldehydes (propanal, butanal, hexanal, octanal, and nonanal) and helional. Subjects (16 < or = n < or = 18) used a 3-alternative forced-choice procedure against carbon-filtered air (blanks), under an ascending concentration approach. Generation, delivery, and control of each vapor were achieved via an 8-station vapor delivery device. Gas chromatography served to quantify the concentrations presented. Group and individual functions were modeled by a sigmoid (logistic) equation. Odor detection thresholds (ODTs) were defined as the concentration producing a detectability (P) halfway (P = 0.5) between chance (P = 0.0) and perfect detection (P = 1.0). ODTs decreased with carbon chain length: 2.0, 0.46, 0.33, and 0.17 ppb, respectively, from propanal to octanal, but the threshold increased for nonanal (0.53 ppb), revealing maximum sensitivity for the 8-carbon member. The strong olfactory receptor (OR) ligands octanal and helional (0.14 ppb) showed the lowest thresholds. ODTs fell at the lower end of previously reported values. Interindividual variability (ODT ratios) amounted to a factor ranging from 10 to 50, lower than typically reported, and was highest for octanal and hexanal. The behavioral dose-response functions emerge at concentrations 2-5 orders of magnitude lower than those required for functions tracing the activation of specific human ORs by the same aldehydes in cell/molecular studies, after all functions were expressed as vapor concentrations.
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Affiliation(s)
- J Enrique Cometto-Muñiz
- Chemosensory Perception Laboratory, Department of Surgery (Otolaryngology), 9500 Gilman Drive-Mail Code 0957, University of California, San Diego, La Jolla, CA 92093-0957, USA.
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