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Zong G, Desfougères Y, Portela-Torres P, Kwon YU, Saiardi A, Shears SB, Wang H. Biochemical and structural characterization of an inositol pyrophosphate kinase from a giant virus. EMBO J 2024; 43:462-480. [PMID: 38216735 PMCID: PMC10897400 DOI: 10.1038/s44318-023-00005-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 11/11/2023] [Accepted: 11/15/2023] [Indexed: 01/14/2024] Open
Abstract
Kinases that synthesize inositol phosphates (IPs) and pyrophosphates (PP-IPs) control numerous biological processes in eukaryotic cells. Herein, we extend this cellular signaling repertoire to viruses. We have biochemically and structurally characterized a minimalist inositol phosphate kinase (i.e., TvIPK) encoded by Terrestrivirus, a nucleocytoplasmic large ("giant") DNA virus (NCLDV). We show that TvIPK can synthesize inositol pyrophosphates from a range of scyllo- and myo-IPs, both in vitro and when expressed in yeast cells. We present multiple crystal structures of enzyme/substrate/nucleotide complexes with individual resolutions from 1.95 to 2.6 Å. We find a heart-shaped ligand binding pocket comprising an array of positively charged and flexible side chains, underlying the observed substrate diversity. A crucial arginine residue in a conserved "G-loop" orients the γ-phosphate of ATP to allow substrate pyrophosphorylation. We highlight additional conserved catalytic and architectural features in TvIPK, and support their importance through site-directed mutagenesis. We propose that NCLDV inositol phosphate kinases may have assisted evolution of inositol pyrophosphate signaling, and we discuss the potential biogeochemical significance of TvIPK in soil niches.
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Affiliation(s)
- Guangning Zong
- Inositol Signaling Group, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Yann Desfougères
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Paloma Portela-Torres
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Yong-Uk Kwon
- Department of Chemistry and Nanoscience, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul, 03760, South Korea
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK.
| | - Stephen B Shears
- Inositol Signaling Group, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
| | - Huanchen Wang
- Inositol Signaling Group, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
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Damstra-Oddy JL, Warren EC, Perry CJ, Desfougères Y, Fitzpatrick JMK, Schaf J, Costelloe L, Hind W, Downer EJ, Saiardi A, Williams RSB. Phytocannabinoid-dependent mTORC1 regulation is dependent upon inositol polyphosphate multikinase activity. Br J Pharmacol 2021; 178:1149-1163. [PMID: 33347604 PMCID: PMC9328663 DOI: 10.1111/bph.15351] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Cannabidiol (CBD) has been shown to differentially regulate the mechanistic target of rapamycin complex 1 (mTORC1) in preclinical models of disease, where it reduces activity in models of epilepsies and cancer and increases it in models of multiple sclerosis (MS) and psychosis. Here, we investigate the effects of phytocannabinoids on mTORC1 and define a molecular mechanism. EXPERIMENTAL APPROACH A novel mechanism for phytocannabinoids was identified using the tractable model system, Dictyostelium discoideum. Using mouse embryonic fibroblasts, we further validate this new mechanism of action. We demonstrate clinical relevance using cells derived from healthy individuals and from people with MS (pwMS). KEY RESULTS Both CBD and the more abundant cannabigerol (CBG) enhance mTORC1 activity in D. discoideum. We identify a mechanism for this effect involving inositol polyphosphate multikinase (IPMK), where elevated IPMK expression reverses the response to phytocannabinoids, decreasing mTORC1 activity upon treatment, providing new insight on phytocannabinoids' actions. We further validated this mechanism using mouse embryonic fibroblasts. Clinical relevance of this effect was shown in primary human peripheral blood mononuclear cells, where CBD and CBG treatment increased mTORC1 activity in cells derived from healthy individuals and decreased mTORC1 activity in cells derived from pwMS. CONCLUSION AND IMPLICATIONS Our findings suggest that both CBD and the abundant CBG differentially regulate mTORC1 signalling through a mechanism dependent on the activity of the upstream IPMK signalling pathway, with potential relevance to the treatment of mTOR-related disorders, including MS.
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Affiliation(s)
- Joseph L Damstra-Oddy
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
| | - Eleanor C Warren
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
| | - Christopher J Perry
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
| | - Yann Desfougères
- Laboratory for Molecular Cell Biology, University College London, London, UK
| | - John-Mark K Fitzpatrick
- Discipline of Physiology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Judith Schaf
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
| | - Lisa Costelloe
- Department of Neurology, Beaumont Hospital, Dublin, Ireland
| | | | - Eric J Downer
- Discipline of Physiology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Adolfo Saiardi
- Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Robin S B Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
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Laha D, Portela-Torres P, Desfougères Y, Saiardi A. Inositol phosphate kinases in the eukaryote landscape. Adv Biol Regul 2020; 79:100782. [PMID: 33422459 PMCID: PMC8024741 DOI: 10.1016/j.jbior.2020.100782] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/15/2020] [Accepted: 12/21/2020] [Indexed: 01/01/2023]
Abstract
Inositol phosphate encompasses a large multifaceted family of signalling molecules that originate from the combinatorial attachment of phosphate groups to the inositol ring. To date, four distinct inositol kinases have been identified, namely, IPK, ITPK, IPPK (IP5-2K), and PPIP5K. Although, ITPKs have recently been identified in archaea, eukaryotes have taken advantage of these enzymes to create a sophisticated signalling network based on inositol phosphates. However, it remains largely elusive what fundamental biochemical principles control the signalling cascade. Here, we present an evolutionary approach to understand the development of the 'inositol phosphate code' in eukaryotes. Distribution analyses of these four inositol kinase groups throughout the eukaryotic landscape reveal the loss of either ITPK, or of PPIP5K proteins in several species. Surprisingly, the loss of IPPK, an enzyme thought to catalyse the rate limiting step of IP6 (phytic acid) synthesis, was also recorded. Furthermore, this study highlights a noteworthy difference between animal (metazoan) and plant (archaeplastida) lineages. While metazoan appears to have a substantial amplification of IPK enzymes, archaeplastida genomes show a considerable increase in ITPK members. Differential evolution of IPK and ITPK between plant and animal lineage is likely reflective of converging functional adaptation of these two types of inositol kinases. Since, the IPK family comprises three sub-types IPMK, IP6K, and IP3-3K each with dedicated enzymatic specificity in metazoan, we propose that the amplified ITPK group in plant could be classified in sub-types with distinct enzymology.
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Affiliation(s)
- Debabrata Laha
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK
| | - Paloma Portela-Torres
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK
| | - Yann Desfougères
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK.
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Azevedo C, Desfougères Y, Jiramongkol Y, Partington H, Trakansuebkul S, Singh J, Steck N, Jessen HJ, Saiardi A. Development of a yeast model to study the contribution of vacuolar polyphosphate metabolism to lysine polyphosphorylation. J Biol Chem 2020; 295:1439-1451. [PMID: 31844018 PMCID: PMC7008358 DOI: 10.1074/jbc.ra119.011680] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/11/2019] [Indexed: 12/13/2022] Open
Abstract
A recently-discovered protein post-translational modification, lysine polyphosphorylation (K-PPn), consists of the covalent attachment of inorganic polyphosphate (polyP) to lysine residues. The nonenzymatic nature of K-PPn means that the degree of this modification depends on both polyP abundance and the amino acids surrounding the modified lysine. K-PPn was originally discovered in budding yeast (Saccharomyces cerevisiae), in which polyP anabolism and catabolism are well-characterized. However, yeast vacuoles accumulate large amounts of polyP, and upon cell lysis, the release of the vacuolar polyP could nonphysiologically cause K-PPn of nuclear and cytosolic targets. Moreover, yeast vacuoles possess two very active endopolyphosphatases, Ppn1 and Ppn2, that could have opposing effects on the extent of K-PPn. Here, we characterized the contribution of vacuolar polyP metabolism to K-PPn of two yeast proteins, Top1 (DNA topoisomerase 1) and Nsr1 (nuclear signal recognition 1). We discovered that whereas Top1-targeting K-PPn is only marginally affected by vacuolar polyP metabolism, Nsr1-targeting K-PPn is highly sensitive to the release of polyP and of endopolyphosphatases from the vacuole. Therefore, to better study K-PPn of cytosolic and nuclear targets, we constructed a yeast strain devoid of vacuolar polyP by targeting the exopolyphosphatase Ppx1 to the vacuole and concomitantly depleting the two endopolyphosphatases (ppn1Δppn2Δ, vt-Ppx1). This strain enabled us to study K-PPn of cytosolic and nuclear targets without the interfering effects of cell lysis on vacuole polyP and of endopolyphosphatases. Furthermore, we also define the fundamental nature of the acidic amino acid residues to the K-PPn target domain.
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Affiliation(s)
- Cristina Azevedo
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom.
| | - Yann Desfougères
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Yannasittha Jiramongkol
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Hamish Partington
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Sasanan Trakansuebkul
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Jyoti Singh
- Institute of Organic Chemistry, University of Freiburg, 79104 Freiburg, Germany
| | - Nicole Steck
- Institute of Organic Chemistry, University of Freiburg, 79104 Freiburg, Germany
| | - Henning J Jessen
- Institute of Organic Chemistry, University of Freiburg, 79104 Freiburg, Germany; CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Adolfo Saiardi
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom.
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Saiardi A, Azevedo C, Desfougères Y, Portela-Torres P, Wilson MSC. Microbial inositol polyphosphate metabolic pathway as drug development target. Adv Biol Regul 2017; 67:74-83. [PMID: 28964726 DOI: 10.1016/j.jbior.2017.09.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 12/27/2022]
Abstract
Inositol polyphosphates are a diverse and multifaceted class of intracellular messengers omnipresent in eukaryotic cells. These water-soluble molecules regulate many aspects of fundamental cell physiology. Removing this metabolic pathway is deleterious: inositol phosphate kinase null mutations can result in lethality or substantial growth phenotypes. Inositol polyphosphate synthesis occurs through the actions of a set of kinases that phosphorylate phospholipase-generated IP3 to higher phosphorylated forms, such as the fully phosphorylated IP6 and the inositol pyrophosphates IP7 and IP8. Unicellular organisms have a reduced array of the kinases for synthesis of higher phosphorylated inositol polyphosphates, while human cells possess two metabolic routes to IP6. The enzymes responsible for inositol polyphosphate synthesis have been identified in all eukaryote genomes, although their amino acid sequence homology is often barely detectable by common search algorithms. Homology between human and microbial inositol phosphate kinases is restricted to a few catalytically important residues. Recent studies of the inositol phosphate metabolic pathways in pathogenic fungi (Cryptococcus neoformans) and protozoa (Trypanosome brucei) have revealed the importance of the highly phosphorylated inositol polyphosphates to the fitness and thus virulence of these pathogens. Given this, identification of inositol kinase inhibitors specifically targeting the kinases of pathogenic microorganisms is desirable and achievable.
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Affiliation(s)
- Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK.
| | - Cristina Azevedo
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Yann Desfougères
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Paloma Portela-Torres
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Miranda S C Wilson
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
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Desfougères Y, Gerasimaitė RU, Jessen HJ, Mayer A. Vtc5, a Novel Subunit of the Vacuolar Transporter Chaperone Complex, Regulates Polyphosphate Synthesis and Phosphate Homeostasis in Yeast. J Biol Chem 2016; 291:22262-22275. [PMID: 27587415 PMCID: PMC5064005 DOI: 10.1074/jbc.m116.746784] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 09/01/2016] [Indexed: 12/23/2022] Open
Abstract
SPX domains control phosphate homeostasis in eukaryotes. Ten genes in yeast encode SPX-containing proteins, among which YDR089W is the only one of unknown function. Here, we show that YDR089W encodes a novel subunit of the vacuole transporter chaperone (VTC) complex that produces inorganic polyphosphate (polyP). The polyP synthesis transfers inorganic phosphate (Pi) from the cytosol into the acidocalcisome- and lysosome-related vacuoles of yeast, where it can be released again. It was therefore proposed for buffer changes in cytosolic Pi concentration (Thomas, M. R., and O'Shea, E. K. (2005) Proc. Natl. Acad. Sci. U.S.A. 102, 9565-9570). Vtc5 physically interacts with the VTC complex and accelerates the accumulation of polyP synthesized by it. Deletion of VTC5 reduces polyP accumulation in vivo and in vitro Its overexpression hyperactivates polyP production and triggers the phosphate starvation response via the PHO pathway. Because this Vtc5-induced starvation response can be reverted by shutting down polyP synthesis genetically or pharmacologically, we propose that polyP synthesis rather than Vtc5 itself is a regulator of the PHO pathway. Our observations suggest that polyP synthesis not only serves to establish a buffer for transient drops in cytosolic Pi levels but that it can actively decrease or increase the steady state of cytosolic Pi.
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Affiliation(s)
- Yann Desfougères
- From the Department of Biochemistry, University of Lausanne, Chemin des Boveresses 155, 1066 Epalinges, Switzerland and
| | - R Uta Gerasimaitė
- From the Department of Biochemistry, University of Lausanne, Chemin des Boveresses 155, 1066 Epalinges, Switzerland and
| | - Henning Jacob Jessen
- the Institute of Organic Chemistry, Albert-Ludwigs-University, 79104 Freiburg, Germany
| | - Andreas Mayer
- From the Department of Biochemistry, University of Lausanne, Chemin des Boveresses 155, 1066 Epalinges, Switzerland and
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Desfougères Y, Neumann H, Mayer A. Organelle size control - increasing vacuole content activates SNAREs to augment organelle volume through homotypic fusion. J Cell Sci 2016; 129:2817-28. [PMID: 27252384 DOI: 10.1242/jcs.184382] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 05/26/2016] [Indexed: 11/20/2022] Open
Abstract
Cells control the size of their compartments relative to cell volume, but there is also size control within each organelle. Yeast vacuoles neither burst nor do they collapse into a ruffled morphology, indicating that the volume of the organellar envelope is adjusted to the amount of content. It is poorly understood how this adjustment is achieved. We show that the accumulating content of yeast vacuoles activates fusion of other vacuoles, thus increasing the volume-to-surface ratio. Synthesis of the dominant compound stored inside vacuoles, polyphosphate, stimulates binding of the chaperone Sec18/NSF to vacuolar SNAREs, which activates them and triggers fusion. SNAREs can only be activated by lumenal, not cytosolic, polyphosphate (polyP). Control of lumenal polyP over SNARE activation in the cytosol requires the cytosolic cyclin-dependent kinase Pho80-Pho85 and the R-SNARE Nyv1. These results suggest that cells can adapt the volume of vacuoles to their content through feedback from the vacuole lumen to the SNAREs on the cytosolic surface of the organelle.
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Affiliation(s)
- Yann Desfougères
- Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, Epalinges 1066, Switzerland
| | - Heinz Neumann
- GZMB, Institut für Molekulare Strukturbiologie, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Andreas Mayer
- Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, Epalinges 1066, Switzerland
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Pieren M, Desfougères Y, Michaillat L, Schmidt A, Mayer A. Vacuolar SNARE protein transmembrane domains serve as nonspecific membrane anchors with unequal roles in lipid mixing. J Biol Chem 2015; 290:12821-32. [PMID: 25817997 DOI: 10.1074/jbc.m115.647776] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Indexed: 12/23/2022] Open
Abstract
Membrane fusion is induced by SNARE complexes that are anchored in both fusion partners. SNAREs zipper up from the N to C terminus bringing the two membranes into close apposition. Their transmembrane domains (TMDs) might be mere anchoring devices, deforming bilayers by mechanical force. Structural studies suggested that TMDs might also perturb lipid structure by undergoing conformational transitions or by zipping up into the bilayer. Here, we tested this latter hypothesis, which predicts that the activity of SNAREs should depend on the primary sequence of their TMDs. We replaced the TMDs of all vacuolar SNAREs (Nyv1, Vam3, and Vti1) by a lipid anchor, by a TMD from a protein unrelated to the membrane fusion machinery, or by artificial leucine-valine sequences. Individual exchange of the native SNARE TMDs against an unrelated transmembrane anchor or an artificial leucine-valine sequence yielded normal fusion activities. Fusion activity was also preserved upon pairwise exchange of the TMDs against unrelated peptides, which eliminates the possibility for specific TMD-TMD interactions. Thus, a specific primary sequence or zippering beyond the SNARE domains is not a prerequisite for fusion. Lipid-anchored Vti1 was fully active, and lipid-anchored Nyv1 permitted the reaction to proceed up to hemifusion, and lipid-anchored Vam3 interfered already before hemifusion. The unequal contribution of proteinaceous TMDs on Vam3 and Nyv1 suggests that Q- and R-SNAREs might make different contributions to the hemifusion intermediate and the opening of the fusion pore. Furthermore, our data support the view that SNARE TMDs serve as nonspecific membrane anchors in vacuole fusion.
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Affiliation(s)
- Michel Pieren
- From the Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | - Yann Desfougères
- From the Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | - Lydie Michaillat
- From the Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | - Andrea Schmidt
- From the Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | - Andreas Mayer
- From the Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
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Gerasimaitė R, Sharma S, Desfougères Y, Schmidt A, Mayer A. Coupled synthesis and translocation restrains polyphosphate to acidocalcisome-like vacuoles and prevents its toxicity. J Cell Sci 2014; 127:5093-104. [DOI: 10.1242/jcs.159772] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Eukaryotes contain inorganic polyphosphate (polyP) and acidocalcisomes, which sequester polyP and store amino acids and divalent cations. Why polyP is sequestered in dedicated organelles has been unknown. We show that polyP produced in the cytosol of yeast becomes toxic. Reconstitution of polyP translocation with purified vacuoles, the acidocalcisomes of yeast, showed that cytosolic polyP cannot be imported whereas polyP produced by the VTC complex, an endogenous vacuolar polyP polymerase, is efficiently imported and does not interfere with growth. PolyP synthesis and import require an electrochemical gradient, probably as a driving force for polyP translocation. VTC exposes its catalytic domain to the cytosol and carries nine vacuolar transmembrane domains. Mutations in the VTC transmembrane regions, which likely constitute the translocation channel, block not only polyP translocation but also synthesis. Since they are far from the cytosolic catalytic domain of VTC, this suggests that the VTC complex obligatorily couples synthesis of polyP to its import in order to avoid toxic intermediates in the cytosol. Sequestration of otherwise toxic polyP may be one reason for the existence of acidocalcisomes in eukaryotes.
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Desfougères Y, Saint-Jalmes A, Salonen A, Vié V, Beaufils S, Pezennec S, Desbat B, Lechevalier V, Nau F. Strong improvement of interfacial properties can result from slight structural modifications of proteins: the case of native and dry-heated lysozyme. Langmuir 2011; 27:14947-14957. [PMID: 22040020 DOI: 10.1021/la203485y] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Identification of the key physicochemical parameters of proteins that determine their interfacial properties is still incomplete and represents a real stake challenge, especially for food proteins. Many studies have thus consisted in comparing the interfacial behavior of different proteins, but it is difficult to draw clear conclusions when the molecules are completely different on several levels. Here the adsorption process of a model protein, the hen egg-white lysozyme, and the same protein that underwent a thermal treatment in the dry state, was characterized. The consequences of this treatment have been previously studied: net charge and hydrophobicity increase and lesser protein stability, but no secondary and tertiary structure modification (Desfougères, Y.; Jardin, J.; Lechevalier, V.; Pezennec, S.; Nau, F. Biomacromolecules 2011, 12, 156-166). The present study shows that these slight modifications dramatically increase the interfacial properties of the protein, since the adsorption to the air-water interface is much faster and more efficient (higher surface pressure). Moreover, a thick and strongly viscoelastic multilayer film is created, while native lysozyme adsorbs in a fragile monolayer film. Another striking result is that completely different behaviors were observed between two molecular species, i.e., native and native-like lysozyme, even though these species could not be distinguished by usual spectroscopic methods. This suggests that the air-water interface could be considered as a useful tool to reveal very subtle differences between protein molecules.
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Desfougères Y, Jardin J, Lechevalier V, Pezennec S, Nau F. Succinimidyl residue formation in hen egg-white lysozyme favors the formation of intermolecular covalent bonds without affecting its tertiary structure. Biomacromolecules 2010; 12:156-66. [PMID: 21166442 DOI: 10.1021/bm101089g] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Protein chemical degradations occur naturally into living cells as soon as proteins have been synthesized. Among these modifications, deamidation of asparagine or glutamine residues has been extensively studied, whereas the intermediate state, a succinimide derivative, was poorly investigated because of the difficulty of isolating those transient species. We used an indirect method, a limited thermal treatment in the dry state at acidic pH, to produce stable cyclic imide residues in hen lysozyme molecules, enabling us to examine the structural and functional properties of so modified proteins. Five cyclic imide rings have been located at sites directly accessible to solvent and did not lead to any changes in secondary or tertiary structures. However, they altered the catalytic properties of lysozyme and significantly decreased the intrinsic stability of the molecules. Moreover, dimerization occurred during the treatment, and this phenomenon was proportional to the extent of chemical degradation. We propose that succinimide formation could be responsible for covalent bond formation under specific physicochemical conditions that could be found in vivo.
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Affiliation(s)
- Yann Desfougères
- Agrocampus Ouest and INRA, UMR1253 STLO, F-35042 Rennes, France.
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Desfougères Y, Croguennec T, Lechevalier V, Bouhallab S, Nau F. Charge and Size Drive Spontaneous Self-Assembly of Oppositely Charged Globular Proteins into Microspheres. J Phys Chem B 2010; 114:4138-44. [DOI: 10.1021/jp9090427] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yann Desfougères
- Agrocampus Ouest, UMR1253, STLO, F-35042 Rennes, France, and INRA, UMR1253, STLO, F-35042 Rennes, France
| | - Thomas Croguennec
- Agrocampus Ouest, UMR1253, STLO, F-35042 Rennes, France, and INRA, UMR1253, STLO, F-35042 Rennes, France
| | - Valérie Lechevalier
- Agrocampus Ouest, UMR1253, STLO, F-35042 Rennes, France, and INRA, UMR1253, STLO, F-35042 Rennes, France
| | - Saïd Bouhallab
- Agrocampus Ouest, UMR1253, STLO, F-35042 Rennes, France, and INRA, UMR1253, STLO, F-35042 Rennes, France
| | - Françoise Nau
- Agrocampus Ouest, UMR1253, STLO, F-35042 Rennes, France, and INRA, UMR1253, STLO, F-35042 Rennes, France
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Desfougères Y, Lechevalier V, Pezennec S, Artzner F, Nau F. Dry-heating makes hen egg white lysozyme an efficient foaming agent and enables its bulk aggregation. J Agric Food Chem 2008; 56:5120-5128. [PMID: 18540622 DOI: 10.1021/jf703715j] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Dry-heating is considered to be one of the most promising approaches to improving the functionality of food proteins. It has been shown that even if only minor structural modifications occur during dry-heating, the foaming properties of proteins are highly improved. With the recent results obtained in the field of foam stabilization by nanoparticles or protein aggregates in mind, a study was undertaken on the impact of dry-heating of lysozyme, used as a model protein, on its foaming properties. This work highlighted the fact that dry-heated hen egg white lysozyme simultaneously exhibited enhanced foaming properties and aggregation capacity. Although the conditions that favored bulk aggregation (high ionic strength, pH, treatment duration, and protein concentration) also favored foaming properties, the large bulk aggregates were not essential to obtain the best functionality. It is envisaged that heat-treated lysozyme may self-associate at the air/water interface, stabilizing air bubbles.
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Affiliation(s)
- Yann Desfougères
- UMR1253, Science et Technologie du Lait et de l'Oeuf, INRA, Agrocampus Rennes, 35000 Rennes, France.
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