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Zhou Y, Liu X, Qi Z, Yang L, Huang C, Lin D. Deciphering the Therapeutic Role of Lactate in Combating Disuse-Induced Muscle Atrophy: An NMR-Based Metabolomic Study in Mice. Molecules 2024; 29:2216. [PMID: 38792078 PMCID: PMC11124173 DOI: 10.3390/molecules29102216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Revised: 05/03/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Disuse muscle atrophy (DMA) is a significant healthcare challenge characterized by progressive loss of muscle mass and function resulting from prolonged inactivity. The development of effective strategies for muscle recovery is essential. In this study, we established a DMA mouse model through hindlimb suspension to evaluate the therapeutic potential of lactate in alleviating the detrimental effects on the gastrocnemius muscle. Using NMR-based metabolomic analysis, we investigated the metabolic changes in DMA-injured gastrocnemius muscles compared to controls and evaluated the beneficial effects of lactate treatment. Our results show that lactate significantly reduced muscle mass loss and improved muscle function by downregulating Murf1 expression, decreasing protein ubiquitination and hydrolysis, and increasing myosin heavy chain levels. Crucially, lactate corrected perturbations in four key metabolic pathways in the DMA gastrocnemius: the biosynthesis of phenylalanine, tyrosine, and tryptophan; phenylalanine metabolism; histidine metabolism; and arginine and proline metabolism. In addition to phenylalanine-related pathways, lactate also plays a role in regulating branched-chain amino acid metabolism and energy metabolism. Notably, lactate treatment normalized the levels of eight essential metabolites in DMA mice, underscoring its potential as a therapeutic agent against the consequences of prolonged inactivity and muscle wasting. This study not only advances our understanding of the therapeutic benefits of lactate but also provides a foundation for novel treatment approaches aimed at metabolic restoration and muscle recovery in conditions of muscle wasting.
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Affiliation(s)
- Yu Zhou
- Key Laboratory of Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361021, China; (Y.Z.); (X.L.)
| | - Xi Liu
- Key Laboratory of Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361021, China; (Y.Z.); (X.L.)
| | - Zhen Qi
- Key Laboratory of Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361021, China; (Y.Z.); (X.L.)
| | - Longhe Yang
- Technical Innovation Center for Utilization of Marine Biological Resources, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361021, China
| | - Caihua Huang
- Research and Communication Center of Exercise and Health, Xiamen University of Technology, Xiamen 361021, China;
| | - Donghai Lin
- Key Laboratory of Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361021, China; (Y.Z.); (X.L.)
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Manoj KM. Murburn posttranslational modifications of proteins: Cellular redox processes and murzyme-mediated metabolo-proteomics. J Cell Physiol 2024; 239:e30954. [PMID: 36716112 DOI: 10.1002/jcp.30954] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/04/2023] [Accepted: 01/11/2023] [Indexed: 01/31/2023]
Abstract
Murburn concept constitutes the thesis that diffusible reactive species or DRS are obligatorily involved in routine metabolic and physiological activities. Murzymes are defined as biomolecules/proteins that generate/modulate/sustain/utilize DRS. Murburn posttranslational modifications (PTMs) result because murburn/murzyme functionalism is integral to cellular existence. Cells must incorporate the inherently stochastic nature of operations mediated by DRS. Due to the earlier/inertial stigmatic perception that DRS are mere agents of chaos, several such outcomes were either understood as deterministic modulations sponsored by house-keeping enzymes or deemed as unregulated nonenzymatic events resulting out of "oxidative stress". In the current review, I dispel the myths around DRS-functions, and undertake systematic parsing and analyses of murburn modifications of proteins. Although it is impossible to demarcate all PTMs into the classical or murburn modalities, telltale signs of the latter are evident from the relative inaccessibility of the locus, non-specificities and mechanistic details. It is pointed out that while many murburn PTMs may be harmless, some others could have deleterious or beneficial physiological implications. Some details of reversible/irreversible modifications of amino acid residues and cofactors that may be subjected to phosphorylation, halogenation, glycosylation, alkylation/acetylation, hydroxylation/oxidation, etc. are listed, along with citations of select proteins where such modifications have been reported. The contexts of these modifications and their significance in (patho)physiology/aging and therapy are also presented. With more balanced explorations and statistically verified data, a definitive understanding of normal versus pathological contexts of murburn modifications would be obtainable in the future.
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Mirveis Z, Howe O, Cahill P, Patil N, Byrne HJ. Monitoring and modelling the glutamine metabolic pathway: a review and future perspectives. Metabolomics 2023; 19:67. [PMID: 37482587 PMCID: PMC10363518 DOI: 10.1007/s11306-023-02031-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 07/03/2023] [Indexed: 07/25/2023]
Abstract
BACKGROUND Analysis of the glutamine metabolic pathway has taken a special place in metabolomics research in recent years, given its important role in cell biosynthesis and bioenergetics across several disorders, especially in cancer cell survival. The science of metabolomics addresses the intricate intracellular metabolic network by exploring and understanding how cells function and respond to external or internal perturbations to identify potential therapeutic targets. However, despite recent advances in metabolomics, monitoring the kinetics of a metabolic pathway in a living cell in situ, real-time and holistically remains a significant challenge. AIM This review paper explores the range of analytical approaches for monitoring metabolic pathways, as well as physicochemical modeling techniques, with a focus on glutamine metabolism. We discuss the advantages and disadvantages of each method and explore the potential of label-free Raman microspectroscopy, in conjunction with kinetic modeling, to enable real-time and in situ monitoring of the cellular kinetics of the glutamine metabolic pathway. KEY SCIENTIFIC CONCEPTS Given its important role in cell metabolism, the ability to monitor and model the glutamine metabolic pathways are highlighted. Novel, label free approaches have the potential to revolutionise metabolic biosensing, laying the foundation for a new paradigm in metabolomics research and addressing the challenges in monitoring metabolic pathways in living cells.
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Affiliation(s)
- Zohreh Mirveis
- FOCAS Research Institute, Technological University Dublin, City Campus, Camden Row, Dublin 8, Ireland.
- School of Physics and Optometric & Clinical Sciences, Technological University Dublin, City Campus, Grangegorman, Dublin 7, Ireland.
| | - Orla Howe
- School of Biological, Health and Sport Sciences, Technological University Dublin, City Campus, Grangegorman, Dublin 7, Ireland
| | - Paul Cahill
- School of Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Nitin Patil
- FOCAS Research Institute, Technological University Dublin, City Campus, Camden Row, Dublin 8, Ireland
- School of Physics and Optometric & Clinical Sciences, Technological University Dublin, City Campus, Grangegorman, Dublin 7, Ireland
| | - Hugh J Byrne
- FOCAS Research Institute, Technological University Dublin, City Campus, Camden Row, Dublin 8, Ireland
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Shimada S, Hoffmann BR, Yang C, Kurth T, Greene AS, Liang M, Dash RK, Cowley AW. Metabolic Responses of Normal Rat Kidneys to a High Salt Intake. FUNCTION 2023; 4:zqad031. [PMID: 37575482 PMCID: PMC10413938 DOI: 10.1093/function/zqad031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 06/06/2023] [Accepted: 06/12/2023] [Indexed: 08/15/2023] Open
Abstract
In this study, novel methods were developed, which allowed continuous (24/7) measurement of arterial blood pressure and renal blood flow in freely moving rats and the intermittent collection of arterial and renal venous blood to estimate kidney metabolic fluxes of O2 and metabolites. Specifically, the study determined the effects of a high salt (HS; 4.0% NaCl) diet upon whole kidney O2 consumption and arterial and renal venous plasma metabolomic profiles of normal Sprague-Dawley rats. A separate group of rats was studied to determine changes in the cortex and outer medulla tissue metabolomic and mRNAseq profiles before and following the switch from a 0.4% to 4.0% NaCl diet. In addition, targeted mRNA expression analysis of cortical segments was performed. Significant changes in the metabolomic and transcriptomic profiles occurred with feeding of the HS diet. A progressive increase of kidney O2 consumption was found despite a reduction in expression of most of the mRNA encoding enzymes of TCA cycle. A novel finding was the increased expression of glycolysis-related genes in Cx and isolated proximal tubular segments in response to an HS diet, consistent with increased release of pyruvate and lactate from the kidney to the renal venous blood. Data suggests that aerobic glycolysis (eg, Warburg effect) may contribute to energy production under these circumstances. The study provides evidence that kidney metabolism responds to an HS diet enabling enhanced energy production while protecting from oxidative stress and injury. Metabolomic and transcriptomic analysis of kidneys of Sprague-Dawley rats fed a high salt diet.
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Affiliation(s)
- Satoshi Shimada
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Brian R Hoffmann
- Mass Spectrometry and Protein Chemistry, Protein Sciences, The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Chun Yang
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Theresa Kurth
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Andrew S Greene
- Mass Spectrometry and Protein Chemistry, Protein Sciences, The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Mingyu Liang
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ranjan K Dash
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Biomedical Engineering, Medical College of Wisconsin and Marquette University, Milwaukee, WI 53226, USA
| | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Manoj KM, Jacob VD, Kavdia M, Tamagawa H, Jaeken L, Soman V. Questioning rotary functionality in the bacterial flagellar system and proposing a murburn model for motility. J Biomol Struct Dyn 2023; 41:15691-15714. [PMID: 36970840 DOI: 10.1080/07391102.2023.2191146] [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: 11/29/2022] [Accepted: 03/09/2023] [Indexed: 03/29/2023]
Abstract
Bacterial flagellar system (BFS) was the primary example of a purported 'rotary-motor' functionality in a natural assembly. This mandates the translation of a circular motion of components inside into a linear displacement of the cell body outside, which is supposedly orchestrated with the following features of the BFS: (i) A chemical/electrical differential generates proton motive force (pmf, including a trans-membrane potential, TMP), which is electro-mechanically transduced by inward movement of protons via BFS. (ii) Membrane-bound proteins of BFS serve as stators and the slender filament acts as an external propeller, culminating into a hook-rod that pierces the membrane to connect to a 'broader assembly of deterministically movable rotor'. We had disclaimed the purported pmf/TMP-based respiratory/photosynthetic physiology involving Complex V, which was also perceived as a 'rotary machine' earlier. We pointed out that the murburn redox logic was operative therein. We pursue the following similar perspectives in BFS-context: (i) Low probability for the evolutionary attainment of an ordered/synchronized teaming of about two dozen types of proteins (assembled across five-seven distinct phases) towards the singular agendum of rotary motility. (ii) Vital redox activity (not the gambit of pmf/TMP!) powers the molecular and macroscopic activities of cells, including flagella. (iii) Flagellar movement is noted even in ambiances lacking/countering the directionality mandates sought by pmf/TMP. (iv) Structural features of BFS lack component(s) capable of harnessing/achieving pmf/TMP and functional rotation. A viable murburn model for conversion of molecular/biochemical activity into macroscopic/mechanical outcomes is proposed herein for understanding BFS-assisted motility. HIGHLIGHTSThe motor-like functionalism of bacterial flagellar system (BFS) is analyzedProton/Ion-differential based powering of BFS is unviable in bacteriaUncouplers-sponsored effects were misinterpreted, resulting in a detour in BFS researchThese findings mandate new explanation for nano-bio-mechanical movements in BFSA minimalist murburn model for the bacterial flagella-aided movement is proposedCommunicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Kelath Murali Manoj
- Satyamjayatu, The Science & Ethics Foundation, Palakkad District, Kerala, India
| | - Vivian David Jacob
- Satyamjayatu, The Science & Ethics Foundation, Palakkad District, Kerala, India
| | - Mahendra Kavdia
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, USA
| | - Hirohisa Tamagawa
- Department of Mechanical Engineering, Gifu University, Gifu City, Japan
| | - Laurent Jaeken
- Department of Industrial Sciences and Technology, Karel de Grote-Hogeschool, Antwerp University Association, Belgium
| | - Vidhu Soman
- Department of Bioscience & Bioengineering, IIT Bombay (& DSS Imagetech Pvt. Ltd), Mumbai, Maharashtra, India
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Shimada S, Hoffmann BR, Yang C, Kurth T, Greene AS, Liang M, Dash RK, Cowley AW. Metabolic responses of normal rat kidneys to a high salt intake. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.18.524636. [PMID: 36711564 PMCID: PMC9882299 DOI: 10.1101/2023.01.18.524636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In the present study, novel methods were developed which allowed continuous (24/7) measurement of blood pressure (BP) and renal blood flow (RBF) in freely moving rats and the intermittent collection of arterial and renal venous blood to estimate kidney metabolic fluxes of O 2 and metabolites. The study determined the effects of a high salt (HS) diet upon whole kidney O 2 consumption and the metabolomic profiles of normal Sprague Dawley (SD) rats. A separate group of rats was studied to determine changes in the cortex (Cx) and outer medulla (OM) tissue metabolomic and mRNAseq profiles before and following the switch from a 0.4% to a 4.0% NaCl diet. Significant changes in the metabolomic and transcriptomic profiles occurred with feeding of the HS diet. A progressive increase of kidney O 2 consumption was found despite a reduction in expression of most of the mRNA encoding enzymes of TCA cycle. Increased glycolysis was evident with the elevation of mRNA expression encoding key glycolytic enzymes and release of pyruvate and lactate from the kidney in the renal venous blood. Glycolytic production of NADH is used in either the production of lactate or oxidized via the malate aspartate shuttle. Aerobic glycolysis (e.g., Warburg-effect) may account for the needed increase in cellular energy. The study provides evidence that kidney metabolism responds to a HS diet enabling enhanced energy production while protecting from oxidate stress and injury.
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Manoj KM, Gideon DA, Bazhin NM, Tamagawa H, Nirusimhan V, Kavdia M, Jaeken L. Na,K-ATPase: A murzyme facilitating thermodynamic equilibriums at the membrane-interface. J Cell Physiol 2023; 238:109-136. [PMID: 36502470 DOI: 10.1002/jcp.30925] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/08/2022] [Accepted: 11/14/2022] [Indexed: 12/14/2022]
Abstract
The redox metabolic paradigm of murburn concept advocates that diffusible reactive species (DRS, particularly oxygen-centric radicals) are mainstays of physiology, and not mere pathological manifestations. The murburn purview of cellular function also integrates the essential principles of bioenergetics, thermogenesis, homeostasis, electrophysiology, and coherence. In this context, any enzyme that generates/modulates/utilizes/sustains DRS functionality is called a murzyme. We have demonstrated that several water-soluble (peroxidases, lactate dehydrogenase, hemogoblin, etc.) and membrane-embedded (Complexes I-V in mitochondria, Photosystems I/II in chloroplasts, rhodopsin/transducin in rod cells, etc.) proteins serve as murzymes. The membrane protein of Na,K-ATPase (NKA, also known as sodium-potassium pump) is the focus of this article, owing to its centrality in neuro-cardio-musculo electrophysiology. Herein, via a series of critical queries starting from the geometric/spatio-temporal considerations of diffusion/mass transfer of solutes in cells to an update on structural/distributional features of NKA in diverse cellular systems, and from various mechanistic aspects of ion-transport (thermodynamics, osmoregulation, evolutionary dictates, etc.) to assays/explanations of inhibitory principles like cardiotonic steroids (CTS), we first highlight some unresolved problems in the field. Thereafter, we propose and apply a minimalist murburn model of trans-membrane ion-differentiation by NKA to address the physiological inhibitory effects of trans-dermal peptide, lithium ion, volatile anesthetics, confirmed interfacial DRS + proton modulators like nitrophenolics and unsaturated fatty acid, and the diverse classes of molecules like CTS, arginine, oximes, etc. These explanations find a pan-systemic connectivity with the inhibitions/uncouplings of other membrane proteins in cells.
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Affiliation(s)
- Kelath Murali Manoj
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2, Kerala, India
| | - Daniel A Gideon
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2, Kerala, India
| | - Nikolai M Bazhin
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk, Russia
| | - Hirohisa Tamagawa
- Department of Mechanical Engineering, Gifu University, Gifu City, Japan
| | - Vijay Nirusimhan
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2, Kerala, India
| | - Mahendra Kavdia
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, USA
| | - Laurent Jaeken
- Department of Industrial Sciences and Technology, Karel de Grote-Hogeschool, Antwerp University Association, Antwerp, Belgium
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Murali Manoj K, Bazhin N, Parashar A, Manekkathodi A, Wu Y. Comprehensive Analyses of the Enhancement of Oxygenesis in Photosynthesis by Bicarbonate and Effects of Diverse Additives: Z-scheme Explanation Versus Murburn Model. Physiology (Bethesda) 2022. [DOI: 10.5772/intechopen.106996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The Z-scheme electron transport chain (ETC) explanation for photosynthesis starts with the serial/sequential transfer of electrons sourced from water molecules bound at Photosystem II via a deterministic array of redox centers (of various stationary/mobile proteins), before \"sinking\" via the reduction of NADP+ bound at flavin-enzyme reductase. Several research groups’ finding that additives (like bicarbonate) enhance the light reaction had divided the research community because it violated the Z-scheme. The untenable aspects of the Z-scheme perception were demonstrated earlier and a murburn bioenergetics (a stochastic/parallel paradigm of ion-radical equilibriums) model was proposed to explain photophosphorylation and Emerson effect. Herein, we further support the murburn model with accurate thermodynamic calculations, which show that the cost of one-electron abstraction from bicarbonate [491 kJ/mol] is lower than water [527 kJ/mol]. Further, copious thioredoxin enables the capture of photoactivated electrons in milieu, which aid in the reduction of nicotinamide nucleotides. The diffusible reactive species (DRS) generated in milieu sponsor phosphorylations and oxygenic reactions. With structural analysis of Photosystems and interacting molecules, we chart out the equations of reactions that explain the loss of labeled O-atom traces in delocalized oxygenesis. Thus, this essay discredits the Z-scheme and explains key outstanding observations in the field.
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Manoj KM, Gideon DA. Structural foundations for explaining the physiological roles of murzymes embedded in diverse phospholipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183981. [PMID: 35690100 DOI: 10.1016/j.bbamem.2022.183981] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/26/2022] [Accepted: 05/30/2022] [Indexed: 06/15/2023]
Abstract
The advent of improved structural biology protocols and bioinformatics methodologies have provided paradigm-shifting insights on metabolic or physiological processes catalyzed by homo-/hetero- proteins (super)complexes embedded in phospholipid membranes of cells/organelles. In this panoramic review, we succinctly elucidate the structural features of select redox proteins from four systems: hepatocyte/adrenal cortex endoplasmic reticulum (microsomes), inner mitochondrial membrane (cristae), thylakoid membrane (grana), and in the flattened disks of rod/cone cells (in retina). Besides catalyzing fast/crucial (photo)chemical reactions, these proteins utilize the redox-active diatomic gaseous molecule of oxygen, the elixir of aerobic life. Quite contrary to extant perceptions that invoke primarily deterministic affinity-binding or conformation-change based "proton-pump"/"serial electron-relay" type roles, we advocate murzyme functions for the membrane-embedded proteins in these systems. Murzymes are proteins that generate/stabilize/utilize diffusible reactive (oxygen) species (DRS/DROS) based activities. Herein, we present a brief compendium of the recently revealed wealth of structural information and mechanistic concepts on how the membrane proteins use DRS/DROS to aid 'effective charge separation' and facilitate trans-membrane dynamics of diverse species in milieu, thereby enabling the cells to function as 'simple chemical engines'.
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Affiliation(s)
- Kelath Murali Manoj
- Satyamjayatu: The Science & Ethics Foundation, Snehatheeram, Shoranur-2 (PO), Kerala 679122, India.
| | - Daniel Andrew Gideon
- Satyamjayatu: The Science & Ethics Foundation, Snehatheeram, Shoranur-2 (PO), Kerala 679122, India.
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Manoj KM, Tamagawa H, Bazhin N, Jaeken L, Nirusimhan V, Faraci F, Gideon DA. Murburn model of vision: Precepts and proof of concept. J Cell Physiol 2022; 237:3338-3355. [PMID: 35662017 DOI: 10.1002/jcp.30786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 05/05/2022] [Accepted: 05/14/2022] [Indexed: 11/08/2022]
Abstract
The classical paradigm of visual physiology comprises of the following features: (i) rod/cone cells located at the rear end of the retina serve as the primary transducers of incoming photo-information, (ii) cis-trans retinal (C20 H28 O) transformations on rhodopsin act as the transduction switch to generate a transmittable signal, (iii) signal amplification occurs via GDP-GTP exchange at transducin, and (iv) the amplified signal is relayed (as an action potential) as a flux-based ripple of Na-K ions along the axons of neurons. Fundamental physical principles, chemical kinetics, and awareness of architecture of eye/retina prompt a questioning of these classical assumptions. In lieu, based on experimental and in silico findings, a simple space-time resolved murburn model for the physiology of phototransduction in the retina is presented wherein molecular oxygen plays key roles. It is advocated that: (a) photo-induced oxygen to superoxide conversion serves as the key step in signal transduction in the visual cycle, (b) all photoactive cells of the retina serve as photoreceptors and rods/cones serve as the ultimate electron source in the retina (deriving oxygen and nutrients from retinal pigmented epithelium), (c) signal amplification is through superoxide mediated phosphorylation of GDP bound to inactive transducin, thereby activating a GDP-based cascade (a new mechanism for trimeric G-proteins), and (d) signal relay is primarily an electron movement along the neuron, from dendritic source to synaptic sink. In particular, we specify the roles for the various modules of transducin and GDP-based activation of phosphodiesterase-6 in the physiology of visual transduction.
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Affiliation(s)
- Kelath Murali Manoj
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2 (PO), Palakkad District, Kerala, India
| | | | - Nikolai Bazhin
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk, Russia
| | - Laurent Jaeken
- Karel de Grote-Hogeschool, Association University and High Schools Antwerp, Antwerpen, Belgium
| | - Vijay Nirusimhan
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2 (PO), Palakkad District, Kerala, India
| | - Federico Faraci
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2 (PO), Palakkad District, Kerala, India
| | - Daniel A Gideon
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Shoranur-2 (PO), Palakkad District, Kerala, India
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Manoj KM, Bazhin NM, Tamagawa H, Jaeken L, Parashar A. The physiological role of complex V in ATP synthesis: Murzyme functioning is viable whereas rotary conformation change model is untenable. J Biomol Struct Dyn 2022; 41:3993-4012. [PMID: 35394896 DOI: 10.1080/07391102.2022.2060307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Complex V or FoF1-ATPase is a multimeric protein found in bioenergetic membranes of cells and organelles like mitochondria/chloroplasts. The popular perception on Complex V deems it as a reversible molecular motor, working bi-directionally (breaking or making ATP) via a conformation-change based chemiosmotic rotary ATP synthesis (CRAS) mechanism, driven by proton-gradients or trans-membrane potential (TMP). In continuance of our pursuits against the CRAS model of cellular bioenergetics, herein we demonstrate the validity of the murburn model based in diffusible reactive (oxygen) species (DRS/DROS). Supported by new in silico derived data (that there are ∼12 adenosine nucleotide binding sites on the F1 bulb and not merely 3 sites, as perceived earlier), available structural information, known experimental observations, and thermodynamic/kinetic considerations (that de-solvation of protons from hydronium ions is facile), we deduce that Complex V serves as a physiological chemostat and a murzyme (enzyme working via murburn scheme, employing DRS). That is- Complex V uses ATP (via consumption at ε or proteins of F1 module) as a Michaelis-Menten substrate to serve as a pH-stat by inletting protons via the c-ring of Fo module. Physiologically, Complex V also functions as a murzyme by presenting ADP/Pi (or their reaction intermediates) on the αβ bulb, thereby enabling greater opportunities for DRS/proton-assisted ATP formation. Thus, the murburn paradigm succeeds the CRAS hypothesis for explaining the role of oxygen in mitochondrial physiologies of oxidative phosphorylation, thermogenesis, TMP and homeostasis.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Kelath Murali Manoj
- Biochemistry Department, Satyamjayatu: The Science & Ethics Foundation, Palakkad, Kerala, India
| | - Nikolai Mikhailovich Bazhin
- Environmental Chemistry Department, Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk, Russia
| | | | - Laurent Jaeken
- Industrial Sciences and Technology, Karel de Grote University College, Antwerp University Association, Hoboken, Belgium
| | - Abhinav Parashar
- Biochemistry Department, Satyamjayatu: The Science & Ethics Foundation, Palakkad, Kerala, India
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