1
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Ameta D, Behera L, Chakraborty A, Sandhan T. Predicting odor from vibrational spectra: a data-driven approach. Sci Rep 2024; 14:20321. [PMID: 39223164 PMCID: PMC11369114 DOI: 10.1038/s41598-024-70696-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Accepted: 08/20/2024] [Indexed: 09/04/2024] Open
Abstract
This study investigates olfaction, a complex and not well-understood sensory modality. The chemical mechanism behind smell can be described by so far proposed two theories: vibrational and docking theories. The vibrational theory has been gaining acceptance lately but needs more extensive validation. To fill this gap for the first time, we, with the help of data-driven classification, clustering, and Explainable AI techniques, systematically analyze a large dataset of vibrational spectra (VS) of 3018 molecules obtained from the atomistic simulation. The study utlizes image representations of VS using Gramian Angular Fields and Markov Transition Fields, allowing computer vision techniques to be applied for better feature extraction and improved odor classification. Furthermore, we fuse the PCA-reduced fingerprint features with image features, which show additional improvement in classification results. We use two clustering methods, agglomerative hierarchical (AHC) and k-means, on dimensionality reduced (UMAP, MDS, t-SNE, and PCA) VS and image features, which shed further insight into the connections between molecular structure, VS, and odor. Additionally, we contrast our method with an earlier work that employed traditional machine learning on fingerprint features for the same dataset, and demonstrate that even with a representative subset of 3018 molecules, our deep learning model outperforms previous results. This comprehensive and systematic analysis highlights the potential of deep learning in furthering the field of olfactory research while confirming the vibrational theory of olfaction.
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Affiliation(s)
- Durgesh Ameta
- Indian Knowledge System and Mental Health Applications Centre, Indian Institute of Technology, Mandi, 175005, India
- Indian Knowledge System Centre, ISS, Delhi, 110065, India
| | - Laxmidhar Behera
- Indian Knowledge System and Mental Health Applications Centre, Indian Institute of Technology, Mandi, 175005, India
- Department of Electrical Engineering, Indian Institute of Technology, Kanpur, 208016, India
| | | | - Tushar Sandhan
- Department of Electrical Engineering, Indian Institute of Technology, Kanpur, 208016, India.
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2
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Pagán OR. The complexities of ligand/receptor interactions: Exploring the role of molecular vibrations and quantum tunnelling. Bioessays 2024; 46:e2300195. [PMID: 38459808 DOI: 10.1002/bies.202300195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 01/19/2024] [Accepted: 02/19/2024] [Indexed: 03/10/2024]
Abstract
Molecular vibrations and quantum tunneling may link ligand binding to the function of pharmacological receptors. The well-established lock-and-key model explains a ligand's binding and recognition by a receptor; however, a general mechanism by which receptors translate binding into activation, inactivation, or modulation remains elusive. The Vibration Theory of Olfaction was proposed in the 1930s to explain this subset of receptor-mediated phenomena by correlating odorant molecular vibrations to smell, but a mechanism was lacking. In the 1990s, inelastic electron tunneling was proposed as a plausible mechanism for translating molecular vibration to odorant physiology. More recently, studies of ligands' vibrational spectra and the use of deuterated ligand analogs have provided helpful information to study this admittedly controversial hypothesis in metabotropic receptors other than olfactory receptors. In the present work, based in part on published experiments from our laboratory using planarians as an experimental organism, I will present a rationale and possible experimental approach for extending this idea to ligand-gated ion channels.
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Affiliation(s)
- Oné R Pagán
- Department of Biology, West Chester University, West Chester, Pennsylvania, USA
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3
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Willeford K. The Luminescence Hypothesis of Olfaction. SENSORS (BASEL, SWITZERLAND) 2023; 23:1333. [PMID: 36772376 PMCID: PMC9919928 DOI: 10.3390/s23031333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/12/2023] [Accepted: 01/20/2023] [Indexed: 06/18/2023]
Abstract
A new hypothesis for the mechanism of olfaction is presented. It begins with an odorant molecule binding to an olfactory receptor. This is followed by the quantum biology event of inelastic electron tunneling as has been suggested with both the vibration and swipe card theories. It is novel in that it is not concerned with the possible effects of the tunneled electrons as has been discussed with the previous theories. Instead, the high energy state of the odorant molecule in the receptor following inelastic electron tunneling is considered. The hypothesis is that, as the high energy state decays, there is fluorescence luminescence with radiative emission of multiple photons. These photons pass through the supporting sustentacular cells and activate a set of olfactory neurons in near-simultaneous timing, which provides the temporal basis for the brain to interpret the required complex combinatorial coding as an odor. The Luminescence Hypothesis of Olfaction is the first to present the necessity of or mechanism for a 1:3 correspondence of odorant molecule to olfactory nerve activations. The mechanism provides for a consistent and reproducible time-based activation of sets of olfactory nerves correlated to an odor. The hypothesis has a biological precedent: an energy feasibility assessment is included, explaining the anosmia seen with COVID-19, and can be confirmed with existing laboratory techniques.
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Affiliation(s)
- Kenneth Willeford
- Coastal Carolinas Integrated Medicine, 10 Doctors Circle, STE 2, Supply, NC 28462, USA
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4
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Feng J, Song B, Zhang Y. Semantic parsing of the life process by quantum biology. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 175:79-89. [PMID: 36126802 DOI: 10.1016/j.pbiomolbio.2022.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/23/2022] [Accepted: 09/13/2022] [Indexed: 06/15/2023]
Abstract
A fact that an ever-increasingly number of research attention has focused on quantum biology demonstrates that it is, by no means, new to works in physic and mathematics, but to molecular biologists, geneticists, and biochemists. This is owing to that quantum biology serves as a distinctive discipline, by using quantum theory to study life sciences in combination with physics, mechanics, mathematics, statistics, and modern biology. Notably, quantum mechanics and its fundamental principles have been employed to clarify complex biological processes and molecular homeostasis within the organic life. Consequently, using the principles of quantum mechanics to study dynamic changes and energy transfer of molecules at the quantum level in biology has been accepted as an unusually distinguishable way to a better explanation of many phenomena in life. It is plausible that a clear conceptual quantum theoretical event is also considered to generally occur for short-term picoseconds or femtoseconds on microscopic nano- and subnanometer scales in biology and biosciences. For instance, photosynthesis, enzyme -catalyzed reactions, magnetic perception, the capture of smell and vision, DNA fragmentation, cellular breathing, mitochondrial processing, as well as brain thinking and consciousness, are all manifested within quantum superposition, quantum coherence, quantum entanglement, quantum tunneling, and other effects. In this mini-review, we describe the recent progress in quantum biology, with a promising direction for further insights into this field.
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Affiliation(s)
- Jing Feng
- Bioengineering College and Graduate School, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing, 400044, China; Chongqing University Jiangjin Hospital, School of Medicine, Chongqing University, No. 725 Jiangzhou Avenue, Dingshan Street, Jiangjin District, Chongqing, 402260, China; The Laboratory of Cell Biochemistry and Topogenetic Regulation, College of Bioengineering & Faculty of Medical Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing, 400044, China
| | - Bo Song
- School of Optical-Electrical Computer Engineering, University of Shanghai for Science and Technology, No. 580 Jungong Road, Yangpu District, Shanghai, 200093, China
| | - Yiguo Zhang
- Chongqing University Jiangjin Hospital, School of Medicine, Chongqing University, No. 725 Jiangzhou Avenue, Dingshan Street, Jiangjin District, Chongqing, 402260, China; The Laboratory of Cell Biochemistry and Topogenetic Regulation, College of Bioengineering & Faculty of Medical Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing, 400044, China.
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5
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Zhang SQ, Cui Y, Li XW, Sun Y, Wang ZW. Multiphonon processes of the inelastic electron transfer in olfaction. Phys Chem Chem Phys 2022; 24:5048-5051. [PMID: 35144279 DOI: 10.1039/d1cp04414a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Inelastic electron transfer, regarded as one of the potential mechanisms to explain odorant recognition in atomic-scale processes, is still a matter of intense debate. Here, we study multiphonon processes of electron transfer using the Markvart model and calculate their lifetimes with the values of key parameters widely adopted in olfactory systems. We find that these multiphonon processes are as quick as the single phonon process, which suggests that contributions from different phonon modes of an odorant molecule should be included for electron transfer in olfaction. Meanwhile, the temperature dependence of electron transfer could be analyzed effectively based on the reorganization energy which is expanded into the linewidth of multiphonon processes. Our theoretical results not only enrich the knowledge of the mechanism of olfaction recognition, but also provide insights into quantum processes in biological systems.
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Affiliation(s)
- Shu-Quan Zhang
- Integrated Chinese and Western Medicine Hospital, Tianjin University, Tianjin 300354, China
| | - Yu Cui
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China.
| | - Xue-Wei Li
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China.
| | - Yong Sun
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China.
| | - Zi-Wu Wang
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China.
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6
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Pandey N, Pal D, Saha D, Ganguly S. Vibration-based biomimetic odor classification. Sci Rep 2021; 11:11389. [PMID: 34059734 PMCID: PMC8166841 DOI: 10.1038/s41598-021-90592-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 05/13/2021] [Indexed: 11/21/2022] Open
Abstract
Olfaction is not as well-understood as vision or audition, nor technologically addressed. Here, Chemical Graph Theory is shown to connect the vibrational spectrum of an odorant molecule, invoked in the Vibration Theory of Olfaction, to its structure, which is germane to the orthodox Shape Theory. Atomistic simulations yield the Eigen-VAlue (EVA) vibrational pseudo-spectra for 20 odorant molecules grouped into 6 different ‘perceptual’ classes by odour. The EVA is decomposed into peaks corresponding to different types of vibrational modes. A novel secondary pseudo-spectrum, informed by this physical insight—the Peak-Decomposed EVA (PD-EVA)—has been proposed here. Unsupervised Machine Learning (spectral clustering), applied to the PD-EVA, clusters the odours into different ‘physical’ (vibrational) classes that match the ‘perceptual’, and also reveal inherent perceptual subclasses. This establishes a physical basis for vibration-based odour classification, harmonizes the Shape and Vibration theories, and points to vibration-based sensing as a promising path towards a biomimetic electronic nose.
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Affiliation(s)
- Nidhi Pandey
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Debasattam Pal
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Dipankar Saha
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Swaroop Ganguly
- Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai, India.
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7
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Liu S, Fu R, Li G. Exploring the mechanism of olfactory recognition in the initial stage by modeling the emission spectrum of electron transfer. PLoS One 2020; 15:e0217665. [PMID: 31923248 PMCID: PMC6953861 DOI: 10.1371/journal.pone.0217665] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 11/29/2019] [Indexed: 11/19/2022] Open
Abstract
Olfactory sense remains elusive regarding the primary reception mechanism. Some studies suggest that olfaction is a spectral sense, the olfactory event is triggered by electron transfer (ET) across the odorants at the active sites of odorant receptors (ORs). Herein we present a Donor-Bridge-Acceptor model, proposing that the ET process can be viewed as an electron hopping from the donor molecule to the odorant molecule (Bridge), then hopping off to the acceptor molecule, making the electronic state of the odorant molecule change along with vibrations (vibronic transition). The odorant specific parameter, Huang–Rhys factor can be derived from ab initio calculations, which make the simulation of ET spectra achievable. In this study, we revealed that the emission spectra (after Gaussian convolution) can be acted as odor characteristic spectra. Using the emission spectrum of ET, we were able to reasonably interpret the similar bitter-almond odors among hydrogen cyanide, benzaldehyde and nitrobenzene. In terms of isotope effects, we succeeded in explaining why subjects can easily distinguish cyclopentadecanone from its fully deuterated analogue cyclopentadecanone-d28 but not distinguishing acetophenone from acetophenone-d8.
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Affiliation(s)
- Shu Liu
- Department of Anatomy, Anhui Medical University, Hefei, Anhui, China
- * E-mail:
| | - Rao Fu
- Department of Anatomy, School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Guangwu Li
- Department of Anatomy, Anhui Medical University, Hefei, Anhui, China
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8
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Abstract
Utilization of electron transfer methods for description of quantum transport is popular due to simplicity of the formulation and its ability to account for basic physics of electron exchange between the system and baths. At the same time, the necessity to go beyond simple golden rule-type expressions for rates was indicated in the literature and ad hoc formulations were proposed. Similarly, kinetic schemes for quantum transport beyond the usual second-order Lindblad/Redfield considerations were discussed. Here we utilize recently introduced the nonequilibrium Hubbard Green's function diagrammatic technique to analyze the construction of rates in open systems. We show that previous considerations for rates of second and fourth order can be obtained as a particular case of zero- and second-order Green's function diagrammatic series with bare diagrams. We discuss limitations of previous considerations, stress advantages of the Hubbard Green's function approach in constructing the rates, and indicate that standard dressing of the diagrams is a natural way to account for additional baths/degrees of freedom in the formulation of generalized expressions for the rates.
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Affiliation(s)
- Nicolas Bergmann
- Department of Chemistry , Technical University of Munich , D-85748 Garching , Germany
| | - Michael Galperin
- Department of Chemistry & Biochemistry , University of California San Diego , La Jolla , California 92093 , United States
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9
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Na M, Liu MT, Nguyen MQ, Ryan K. Single-Neuron Comparison of the Olfactory Receptor Response to Deuterated and Nondeuterated Odorants. ACS Chem Neurosci 2019; 10:552-562. [PMID: 30343564 DOI: 10.1021/acschemneuro.8b00416] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The mammalian olfactory receptors (ORs) constitute a large subfamily of the Class A G-protein coupled receptors (GPCRs). The molecular details of how these receptors convert odorant chemical information into neural signal are unknown, but are predicted by analogy to other GPCRs to involve stabilization of the activated form of the OR by the odorant. An alternative hypothesis maintains that the vibrational modes of an odorant's bonds constitute the main determinant for OR activation, and that odorants containing deuterium in place of hydrogen should activate different sets of OR family members. Experiments using heterologously expressed ORs have failed to show different responses for deuterated odorants, but experiments in the sensory neuron environment have been lacking. We tested the response to deuterated and nondeuterated versions of p-cymene, 1-octanol, 1-undecanol, and octanal in dissociated mouse olfactory receptor neurons (ORNs) by calcium imaging. In all, we tested 23 812 cells, including a subset expressing recombinant mouse olfactory receptor 2 ( Olfr2/OR-I7 ), and found that nearly all of the 1610 odorant-responding neurons were unable to distinguish the D- and H-odorants. These results support the conclusion that if mammals can perceive deuterated odorants differently, the difference arises from the receptor-independent steps of olfaction. Nevertheless, 0.81% of the responding ORNs responded differently to D- and H-odorants, and those in the octanal experiments responded selectively to H-octanal at concentrations from 3 to 100 μM. The few ORs responding differently to H and D may be hypersensitive to one of the several H/D physicochemical differences, such as the difference in H/D hydrophobicity.
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Affiliation(s)
- Mihwa Na
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
| | - Min Ting Liu
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
| | - Minh Q. Nguyen
- Taste and Smell Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Kevin Ryan
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
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10
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Deciphering the Odorant Binding, Activation, and Discrimination Mechanism of Dhelobp21 from Dastarus Helophoroides. Sci Rep 2018; 8:13506. [PMID: 30202068 PMCID: PMC6131269 DOI: 10.1038/s41598-018-31959-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 08/28/2018] [Indexed: 01/17/2023] Open
Abstract
Odorant-binding proteins (OBPs) play a pivotal role in transporting odorants through the sensillar lymph of insect chemosensory sensilla and increasing the sensitivity of the olfactory system. To address the ligand binding, activation, and release mechanisms of OBPs, we performed a set of conventional molecular dynamics simulations for binding of the odorant-binding protein DhelOBP21 from Dastarcus helophoroides with 18 ligands (1-NPN and 17 volatiles), as well as four constant-pH molecular dynamics simulations. We found that the open pocket DhelOBP21 at pH 5.0 could bind volatiles and form a closed pocket complex via transformation of its N-terminus into regular Helix at pH 7.0 and vice versa. Moreover, the discrimination of volatiles (selectivity and promiscuity) was determined by the characteristics of both the volatiles and the ‘essential’ and ‘selective’ amino acid residues in OBP binding pockets, rather than the binding affinity of the volatiles. This study put forward a new hypothesis that during the binding of volatiles there are two transitions for the DhelOBP21 amino-terminus: pH- and odorant binding-dependent random-coil-to-helix. Another important finding is providing a framework for the exploration of the complete coil-to-helix transition process and theoretically analyzing its underlying causes at molecular level.
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11
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Abstract
We propose a technologically feasible one-dimensional double barrier resonant tunneling diode (RTD) as electronic nose, inspired by the vibration theory of biological olfaction. The working principle is phonon-assisted inelastic electron tunneling spectroscopy (IETS), modeled here using the Non-Equilibrium Green Function formalism for quantum transport. While standard IETS requires low-temperature operation to obviate the thermal broadening of spectroscopic peaks, we show that quantum confinement in the well of the RTD provides electron energy filtering in this case and could thereby allow room-temperature operation. We also find that the IETS peaks - corresponding to adsorbed foreign molecules - shift monotonically along the bias voltage coordinate with their vibrational energy, promising a selective sensor.
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12
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Singletary M, Hagerty S, Muramoto S, Daniels Y, MacCrehan WA, Stan G, Lau JW, Pustovyy O, Globa L, Morrison EE, Sorokulova I, Vodyanoy V. PEGylation of zinc nanoparticles amplifies their ability to enhance olfactory responses to odorant. PLoS One 2017; 12:e0189273. [PMID: 29261701 PMCID: PMC5738065 DOI: 10.1371/journal.pone.0189273] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 11/22/2017] [Indexed: 12/03/2022] Open
Abstract
Olfactory responses are intensely enhanced with the addition of endogenous and engineered primarily-elemental small zinc nanoparticles (NPs). With aging, oxidation of these Zn nanoparticles eliminated the observed enhancement. The design of a polyethylene glycol coating to meet storage requirements of engineered zinc nanoparticles is evaluated to achieve maximal olfactory benefit. The zinc nanoparticles were covered with 1000 g/mol or 400 g/mol molecular weight polyethylene glycol (PEG). Non-PEGylated and PEGylated zinc nanoparticles were tested by electroolfactogram with isolated rat olfactory epithelium and odorant responses evoked by the mixture of eugenol, ethyl butyrate and (±) carvone after storage at 278 K (5 oC), 303 K (30 oC) and 323 K (50 oC). The particles were analyzed by atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and laser Doppler velocimetry. Our data indicate that stored ZnPEG400 nanoparticles maintain physiologically-consistent olfactory enhancement for over 300 days. These engineered Nanoparticles support future applications in olfactory research, sensitive detection, and medicine.
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Affiliation(s)
- Melissa Singletary
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama, United States of America
| | - Samantha Hagerty
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama, United States of America
| | - Shin Muramoto
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - Yasmine Daniels
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - William A MacCrehan
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - Gheorghe Stan
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - June W Lau
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - Oleg Pustovyy
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama, United States of America
| | - Ludmila Globa
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama, United States of America
| | - Edward E Morrison
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama, United States of America
| | - Iryna Sorokulova
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama, United States of America
| | - Vitaly Vodyanoy
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama, United States of America
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13
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Wolf S, Jovancevic N, Gelis L, Pietsch S, Hatt H, Gerwert K. Dynamical Binding Modes Determine Agonistic and Antagonistic Ligand Effects in the Prostate-Specific G-Protein Coupled Receptor (PSGR). Sci Rep 2017; 7:16007. [PMID: 29167480 PMCID: PMC5700038 DOI: 10.1038/s41598-017-16001-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 11/03/2017] [Indexed: 01/14/2023] Open
Abstract
We analysed the ligand-based activation mechanism of the prostate-specific G-protein coupled receptor (PSGR), which is an olfactory receptor that mediates cellular growth in prostate cancer cells. Furthermore, it is an olfactory receptor with a known chemically near identic antagonist/agonist pair, α- and β-ionone. Using a combined theoretical and experimental approach, we propose that this receptor is activated by a ligand-induced rearrangement of a protein-internal hydrogen bond network. Surprisingly, this rearrangement is not induced by interaction of the ligand with the network, but by dynamic van der Waals contacts of the ligand with the involved amino acid side chains, altering their conformations and intraprotein connectivity. Ligand recognition in this GPCR is therefore highly stereo selective, but seemingly lacks any ligand recognition via polar contacts. A putative olfactory receptor-based drug design scheme will have to take this unique mode of protein/ligand action into account.
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Affiliation(s)
- Steffen Wolf
- Department of Biophysics, ND 04 North, Ruhr-University Bochum, 44780, Bochum, Germany.
- Department of Biophysics, CAS-MPG Partner Institute for Computational Biology, Key Laboratory of Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031, Shanghai, P.R. China.
| | - Nikolina Jovancevic
- Department of Cellphysiology, ND 4, Ruhr-University Bochum, 44780, Bochum, Germany
| | - Lian Gelis
- Department of Cellphysiology, ND 4, Ruhr-University Bochum, 44780, Bochum, Germany
| | - Sebastian Pietsch
- Department of Biophysics, ND 04 North, Ruhr-University Bochum, 44780, Bochum, Germany
| | - Hanns Hatt
- Department of Cellphysiology, ND 4, Ruhr-University Bochum, 44780, Bochum, Germany
| | - Klaus Gerwert
- Department of Biophysics, ND 04 North, Ruhr-University Bochum, 44780, Bochum, Germany
- Department of Biophysics, CAS-MPG Partner Institute for Computational Biology, Key Laboratory of Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031, Shanghai, P.R. China
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14
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Abstract
OBJECTIVE This article aims to address the need to rethink the classification of mental illness and to draw attention to the current use of quantum biology and its likely future use in understanding the nature of mental illness. CONCLUSION It is desirable to separate out neuroscience and clinical research and to become better acquainted with the concepts of quantum mechanical/quantum biological theory and its contribution to medicine.
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15
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Wolf S, Gelis L, Dörrich S, Hatt H, Kraft P. Evidence for a shape-based recognition of odorants in vivo in the human nose from an analysis of the molecular mechanism of lily-of-the-valley odorants detection in the Lilial and Bourgeonal family using the C/Si/Ge/Sn switch strategy. PLoS One 2017; 12:e0182147. [PMID: 28763484 PMCID: PMC5538716 DOI: 10.1371/journal.pone.0182147] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 07/13/2017] [Indexed: 01/20/2023] Open
Abstract
We performed an analysis of possible mechanisms of ligand recognition in the human nose. The analysis is based on in vivo odor threshold determination and in vitro Ca2+ imaging assays with a C/Si/Ge/Sn switch strategy applied to the compounds Lilial and Bourgeonal, to differentiate between different molecular mechanisms of odorant detection. Our results suggest that odorant detection under threshold conditions is mainly based on the molecular shape, i.e. the van der Waals surface, and electrostatics of the odorants. Furthermore, we show that a single olfactory receptor type is responsible for odor detection of Bourgeonal at the threshold level in humans in vivo. Carrying out a QM analysis of vibrational energies contained in the odorants, there is no evidence for a vibration-based recognition.
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Affiliation(s)
- Steffen Wolf
- Department of Biophysics, CAS-MPG Partner Institute for Computational Biology, Key Laboratory of Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, P.R. China
- Department of Biophysics, Ruhr-University Bochum, Bochum, Germany
| | - Lian Gelis
- Department of Cellphysiology, Ruhr-University Bochum, Bochum, Germany
| | - Steffen Dörrich
- Institute of Inorganic Chemistry, University of Würzburg, Würzburg, Germany
| | - Hanns Hatt
- Department of Cellphysiology, Ruhr-University Bochum, Bochum, Germany
| | - Philip Kraft
- Fragrance Research, Givaudan Schweiz AG, Dübendorf, Switzerland
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16
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Experimental evaluation of the generalized vibrational theory of G protein-coupled receptor activation. Proc Natl Acad Sci U S A 2017; 114:5595-5600. [PMID: 28500275 DOI: 10.1073/pnas.1618422114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Recently, an alternative theory concerning the method by which olfactory proteins are activated has garnered attention. This theory proposes that the activation of olfactory G protein-coupled receptors occurs by an inelastic electron tunneling mechanism that is mediated through the presence of an agonist with an appropriate vibrational state to accept the inelastic portion of the tunneling electron's energy. In a recent series of papers, some suggestive theoretical evidence has been offered that this theory may be applied to nonolfactory G protein-coupled receptors (GPCRs), including those associated with the central nervous system (CNS). [Chee HK, June OS (2013) Genomics Inform 11(4):282-288; Chee HK, et al. (2015) FEBS Lett 589(4):548-552; Oh SJ (2012) Genomics Inform 10(2):128-132]. Herein, we test the viability of this idea, both by receptor affinity and receptor activation measured by calcium flux. This test was performed using a pair of well-characterized agonists for members of the 5-HT2 class of serotonin receptors, 2,5-dimethoxy-4-iodoamphetamine (DOI) and N,N-dimethyllysergamide (DAM-57), and their respective deuterated isotopologues. No evidence was found that selective deuteration affected either the binding affinity or the activation by the selected ligands for the examined members of the 5-HT2 receptor class.
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Hagerty S, Daniels Y, Singletary M, Pustovyy O, Globa L, MacCrehan WA, Muramoto S, Stan G, Lau JW, Morrison EE, Sorokulova I, Vodyanoy V. After oxidation, zinc nanoparticles lose their ability to enhance responses to odorants. Biometals 2016; 29:1005-1018. [PMID: 27649965 DOI: 10.1007/s10534-016-9972-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/09/2016] [Indexed: 01/13/2023]
Abstract
Electrical responses of olfactory sensory neurons to odorants were examined in the presence of zinc nanoparticles of various sizes and degrees of oxidation. The zinc nanoparticles were prepared by the underwater electrical discharge method and analyzed by atomic force microscopy and X-ray photoelectron spectroscopy. Small (1.2 ± 0.3 nm) zinc nanoparticles significantly enhanced electrical responses of olfactory neurons to odorants. After oxidation, however, these small zinc nanoparticles were no longer capable of enhancing olfactory responses. Larger zinc oxide nanoparticles (15 nm and 70 nm) also did not modulate responses to odorants. Neither zinc nor zinc oxide nanoparticles produced olfactory responses when added without odorants. The enhancement of odorant responses by small zinc nanoparticles was explained by the creation of olfactory receptor dimers initiated by small zinc nanoparticles. The results of this work will clarify the mechanisms for the initial events in olfaction, as well as to provide new ways to alleviate anosmia related to the loss of olfactory receptors.
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Affiliation(s)
- Samantha Hagerty
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL, USA
| | - Yasmine Daniels
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Melissa Singletary
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL, USA
| | - Oleg Pustovyy
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL, USA
| | - Ludmila Globa
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL, USA
| | - William A MacCrehan
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Shin Muramoto
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Gheorghe Stan
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - June W Lau
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Edward E Morrison
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL, USA
| | - Iryna Sorokulova
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL, USA
| | - Vitaly Vodyanoy
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL, USA.
- Auburn University, 109 Greene Hall, Auburn, AL, 36849, USA.
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Watson IPB, Brüne M, Bradley AJ. The evolution of the molecular response to stress and its relevance to trauma and stressor-related disorders. Neurosci Biobehav Rev 2016; 68:134-147. [PMID: 27216210 DOI: 10.1016/j.neubiorev.2016.05.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 04/29/2016] [Accepted: 05/11/2016] [Indexed: 02/08/2023]
Abstract
The experience of "stress", in its broadest meaning, is an inevitable part of life. All living creatures have evolved multiple mechanisms to deal with such threats and challenges and to avoid damage to the organism that may be incurred from these stress responses. Trauma and stressor-related disorders are psychiatric conditions that are caused specifically by the experience of stress, though depression, anxiety and some other disorders may also be unleashed by stress. Stress, however, is not a mandatory criterion of these diagnoses. This article focuses on the evolution of the neurochemicals involved in the response to stress and the systems in which they function. This includes the skin and gut, and the immune system. Evidence suggests that responses to stress are evolutionarily highly conserved, have wider involvement than the hypothalamic pituitary adrenal stress axis alone, and that excessive stress responses can produce stressor-related disorders in both humans and animals.
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Affiliation(s)
- Ian P Burges Watson
- University of Tasmania, Department of Psychiatry, Hobart, Tasmania 7005, Australia
| | - Martin Brüne
- LWL University Hospital, Department of Psychiatry, Division of Cognitive Neuropsychiatry, Ruhr-University Bochum, Germany.
| | - Adrian J Bradley
- School of Biomedical Sciences, Faculty of Medicine and Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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19
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How Far Does a Receptor Influence Vibrational Properties of an Odorant? PLoS One 2016; 11:e0152345. [PMID: 27014869 PMCID: PMC4807836 DOI: 10.1371/journal.pone.0152345] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Accepted: 03/11/2016] [Indexed: 11/19/2022] Open
Abstract
The biophysical mechanism of the sense of smell, or olfaction, is still highly debated. The mainstream explanation argues for a shape-based recognition of odorant molecules by olfactory receptors, while recent investigations suggest the primary olfactory event to be triggered by a vibrationally-assisted electron transfer reaction. We consider this controversy by studying the influence of a receptor on the vibrational properties of an odorant in atomistic details as the coupling between electronic degrees of freedom of the receptor and the vibrations of the odorant is the key parameter of the vibrationally-assisted electron transfer. Through molecular dynamics simulations we elucidate the binding specificity of a receptor towards acetophenone odorant. The vibrational properties of acetophenone inside the receptor are then studied by the polarizable embedding density functional theory approach, allowing to quantify protein-odorant interactions. Finally, we judge whether the effects of the protein provide any indications towards the existing theories of olfaction.
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Jia H, Pustovyy OM, Wang Y, Waggoner P, Beyers RJ, Schumacher J, Wildey C, Morrison E, Salibi N, Denney TS, Vodyanoy VJ, Deshpande G. Enhancement of Odor-Induced Activity in the Canine Brain by Zinc Nanoparticles: A Functional MRI Study in Fully Unrestrained Conscious Dogs. Chem Senses 2015; 41:53-67. [PMID: 26464498 DOI: 10.1093/chemse/bjv054] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Using noninvasive in vivo functional magnetic resonance imaging (fMRI), we demonstrate that the enhancement of odorant response of olfactory receptor neurons by zinc nanoparticles leads to increase in activity in olfaction-related and higher order areas of the dog brain. To study conscious dogs, we employed behavioral training and optical motion tracking for reducing head motion artifacts. We obtained brain activation maps from dogs in both anesthetized state and fully conscious and unrestrained state. The enhancement effect of zinc nanoparticles was higher in conscious dogs with more activation in higher order areas as compared with anesthetized dogs. In conscious dogs, voxels in the olfactory bulb and hippocampus showed higher activity to odorants mixed with zinc nanoparticles as compared with pure odorants, odorants mixed with gold nanoparticles as well as zinc nanoparticles alone. These regions have been implicated in odor intensity processing in other species including humans. If the enhancement effect of zinc nanoparticles observed in vivo are confirmed by future behavioral studies, zinc nanoparticles may provide a way for enhancing the olfactory sensitivity of canines for detection of target substances such as explosives and contraband substances at very low concentrations, which would otherwise go undetected.
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Affiliation(s)
- Hao Jia
- AU MRI Research Center, Department of Electrical & Computer Engineering, Auburn University, Auburn, AL 36832, USA, College of Information Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China
| | - Oleg M Pustovyy
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, AL 36832, USA
| | - Yun Wang
- AU MRI Research Center, Department of Electrical & Computer Engineering, Auburn University, Auburn, AL 36832, USA
| | - Paul Waggoner
- Canine Detection Research Institute, Auburn University, Auburn, AL 36832, USA
| | - Ronald J Beyers
- AU MRI Research Center, Department of Electrical & Computer Engineering, Auburn University, Auburn, AL 36832, USA
| | - John Schumacher
- Department of Clinical Sciences, Auburn University, Auburn, AL 36832, USA
| | | | - Edward Morrison
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, AL 36832, USA
| | - Nouha Salibi
- MR R&D, Siemens Healthcare, Malvern, PA 19355, USA
| | - Thomas S Denney
- AU MRI Research Center, Department of Electrical & Computer Engineering, Auburn University, Auburn, AL 36832, USA, Department of Psychology, Auburn University, Auburn, AL 36832, USA and Alabama Advanced Imaging Consortium, Auburn University and University of Alabama Birmingham, AL, USA
| | - Vitaly J Vodyanoy
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, AL 36832, USA,
| | - Gopikrishna Deshpande
- AU MRI Research Center, Department of Electrical & Computer Engineering, Auburn University, Auburn, AL 36832, USA, Department of Psychology, Auburn University, Auburn, AL 36832, USA and Alabama Advanced Imaging Consortium, Auburn University and University of Alabama Birmingham, AL, USA
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Block E, Jang S, Matsunami H, Sekharan S, Dethier B, Ertem MZ, Gundala S, Pan Y, Li S, Li Z, Lodge SN, Ozbil M, Jiang H, Penalba SF, Batista VS, Zhuang H. Implausibility of the vibrational theory of olfaction. Proc Natl Acad Sci U S A 2015; 112:E2766-74. [PMID: 25901328 PMCID: PMC4450420 DOI: 10.1073/pnas.1503054112] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the active sites of odorant receptors (ORs), serving as a sensitive measure of odorant vibrational frequencies, ultimately leading to olfactory perception. A previous study reported that human subjects differentiated hydrogen/deuterium isotopomers (isomers with isotopic atoms) of the musk compound cyclopentadecanone as evidence supporting the theory. Here, we find no evidence for such differentiation at the molecular level. In fact, we find that the human musk-recognizing receptor, OR5AN1, identified using a heterologous OR expression system and robustly responding to cyclopentadecanone and muscone, fails to distinguish isotopomers of these compounds in vitro. Furthermore, the mouse (methylthio)methanethiol-recognizing receptor, MOR244-3, as well as other selected human and mouse ORs, responded similarly to normal, deuterated, and (13)C isotopomers of their respective ligands, paralleling our results with the musk receptor OR5AN1. These findings suggest that the proposed vibration theory does not apply to the human musk receptor OR5AN1, mouse thiol receptor MOR244-3, or other ORs examined. Also, contrary to the vibration theory predictions, muscone-d30 lacks the 1,380- to 1,550-cm(-1) IR bands claimed to be essential for musk odor. Furthermore, our theoretical analysis shows that the proposed electron transfer mechanism of the vibrational frequencies of odorants could be easily suppressed by quantum effects of nonodorant molecular vibrational modes. These and other concerns about electron transfer at ORs, together with our extensive experimental data, argue against the plausibility of the vibration theory.
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Affiliation(s)
- Eric Block
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222;
| | - Seogjoo Jang
- Department of Chemistry and Biochemistry, Queens College, and Graduate Center, City University of New York, Flushing, NY 11367;
| | - Hiroaki Matsunami
- Department of Molecular Genetics and Microbiology and Department of Neurobiology, Duke Institute for Brain Sciences, Duke University Medical Center, Durham, NC 27710;
| | | | - Bérénice Dethier
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222
| | - Mehmed Z Ertem
- Department of Chemistry, Yale University, New Haven, CT 06520; Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
| | - Sivaji Gundala
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222
| | - Yi Pan
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and
| | - Shengju Li
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and
| | - Zhen Li
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and
| | - Stephene N Lodge
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222
| | - Mehmet Ozbil
- Department of Chemistry, Yale University, New Haven, CT 06520
| | - Huihong Jiang
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and
| | - Sonia F Penalba
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222
| | | | - Hanyi Zhuang
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and Institute of Health Sciences, Shanghai Jiao tong University School of Medicine/Shanghai Institutes for Biological Sciences of Chinese Academy of Sciences, Shanghai 200031, China
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22
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Bell IR, Schwartz GE. Enhancement of adaptive biological effects by nanotechnology preparation methods in homeopathic medicines. HOMEOPATHY 2015; 104:123-38. [DOI: 10.1016/j.homp.2014.11.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Accepted: 11/16/2014] [Indexed: 01/19/2023]
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23
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Don CG, Riniker S. Scents and sense:In silicoperspectives on olfactory receptors. J Comput Chem 2014; 35:2279-87. [DOI: 10.1002/jcc.23757] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/23/2014] [Accepted: 09/27/2014] [Indexed: 11/12/2022]
Affiliation(s)
- Charleen G. Don
- Swiss Federal Institute of Technology, Laboratory of Physical Chemistry, ETH Zurich; 8093 Zurich Switzerland
| | - Sereina Riniker
- Swiss Federal Institute of Technology, Laboratory of Physical Chemistry, ETH Zurich; 8093 Zurich Switzerland
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Dörrich S, Gelis L, Wolf S, Sunderkötter A, Mahler C, Guschina E, Tacke R, Hatt H, Kraft P. Comparative Analysis of the Olfactory Properties of Silicon/Germanium/Tin Analogues of the Lily-of-the-Valley Odorants Lilial and Bourgeonal. Chempluschem 2014. [DOI: 10.1002/cplu.201402160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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25
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Post-Translational Modifications of TRP Channels. Cells 2014; 3:258-87. [PMID: 24717323 PMCID: PMC4092855 DOI: 10.3390/cells3020258] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 03/25/2014] [Accepted: 03/27/2014] [Indexed: 01/07/2023] Open
Abstract
Transient receptor potential (TRP) channels constitute an ancient family of cation channels that have been found in many eukaryotic organisms from yeast to human. TRP channels exert a multitude of physiological functions ranging from Ca2+ homeostasis in the kidney to pain reception and vision. These channels are activated by a wide range of stimuli and undergo covalent post-translational modifications that affect and modulate their subcellular targeting, their biophysical properties, or channel gating. These modifications include N-linked glycosylation, protein phosphorylation, and covalent attachment of chemicals that reversibly bind to specific cysteine residues. The latter modification represents an unusual activation mechanism of ligand-gated ion channels that is in contrast to the lock-and-key paradigm of receptor activation by its agonists. In this review, we summarize the post-translational modifications identified on TRP channels and, when available, explain their physiological role.
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