1
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Freeman EL, Ward R, Murphy MM, Wang T, Ryder J. Comprehensive safety assessment of serendipity berry sweet protein produced from Komagataella phaffii. Regul Toxicol Pharmacol 2024; 147:105562. [PMID: 38190935 DOI: 10.1016/j.yrtph.2024.105562] [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: 09/18/2023] [Revised: 11/29/2023] [Accepted: 01/03/2024] [Indexed: 01/10/2024]
Abstract
Serendipity berry plant (Dioscoreophyllum cumminsii (Stapf) Diels) is the source of a naturally sweet protein referred to as monellin. The safety of serendipity berry sweet protein (SBSP) containing single polypeptide monellin (MON) expressed in Komagataella phaffii (formerly Pichia pastoris) and produced via precision fermentation was examined comprehensively through assessments of in vitro and in silico protein digestion, in silico allergenicity, in vitro genotoxicity (reverse mutation and mammalian micronucleus assays), and 14-day and 90-day oral (dietary) toxicity studies in rats. There was no indication of allergenicity for SBSP in the in silico analyses. Results from both in vitro and in silico protein digestibility assessments indicated that SBSP is digested upon ingestion and would therefore be unlikely to pose a toxigenic or allergenic risk to consumers. SBSP was non-genotoxic in in vitro assays and showed no adverse effects in the 14-day or 90-day toxicity studies up to the highest dose tested. The 90-day toxicity study supports a NOAEL for SBSP of 1954 mg/kg bw/day, which corresponds to a NOAEL for MON of 408 mg/kg bw/day.
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Affiliation(s)
- Elaine L Freeman
- Exponent Inc., Center for Chemical Regulation and Food Safety, 1150 Connecticut Ave NW, Suite 1100, Washington, DC, 20036, USA.
| | - Rachel Ward
- Exponent Inc., Center for Chemical Regulation and Food Safety, 1150 Connecticut Ave NW, Suite 1100, Washington, DC, 20036, USA
| | - Mary M Murphy
- Exponent Inc., Center for Chemical Regulation and Food Safety, 1150 Connecticut Ave NW, Suite 1100, Washington, DC, 20036, USA
| | - Tina Wang
- Oobli, Inc., 202 Cousteau Place, Suite 210, Davis, CA, 95618, USA
| | - Jason Ryder
- Oobli, Inc., 202 Cousteau Place, Suite 210, Davis, CA, 95618, USA; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA.
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2
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Monzon AM, Bonato P, Necci M, Tosatto SCE, Piovesan D. FLIPPER: Predicting and Characterizing Linear Interacting Peptides in the Protein Data Bank. J Mol Biol 2021; 433:166900. [PMID: 33647288 DOI: 10.1016/j.jmb.2021.166900] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/22/2021] [Accepted: 02/22/2021] [Indexed: 12/31/2022]
Abstract
A large fraction of peptides or protein regions are disordered in isolation and fold upon binding. These regions, also called MoRFs, SLiMs or LIPs, are often associated with signaling and regulation processes. However, despite their importance, only a limited number of examples are available in public databases and their automatic detection at the proteome level is problematic. Here we present FLIPPER, an automatic method for the detection of structurally linear sub-regions or peptides that interact with another chain in a protein complex. FLIPPER is a random forest classification that takes the protein structure as input and provides the propensity of each amino acid to be part of a LIP region. Models are built taking into consideration structural features such as intra- and inter-chain contacts, secondary structure, solvent accessibility in both bound and unbound state, structural linearity and chain length. FLIPPER is accurate when evaluated on non-redundant independent datasets, 99% precision and 99% sensitivity on PixelDB-25 and 87% precision and 88% sensitivity on DIBS-25. Finally, we used FLIPPER to process the entire Protein Data Bank and identified different classes of LIPs based on different binding modes and partner molecules. We provide a detailed description of these LIP categories and show that a large fraction of these regions are not detected by disorder predictors. All FLIPPER predictions are integrated in the MobiDB 4.0 database.
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Affiliation(s)
| | - Paolo Bonato
- Dept. of Biomedical Sciences, University of Padua, Via Ugo Bassi 58/B, Padua 35121, Italy
| | - Marco Necci
- Dept. of Biomedical Sciences, University of Padua, Via Ugo Bassi 58/B, Padua 35121, Italy
| | - Silvio C E Tosatto
- Dept. of Biomedical Sciences, University of Padua, Via Ugo Bassi 58/B, Padua 35121, Italy.
| | - Damiano Piovesan
- Dept. of Biomedical Sciences, University of Padua, Via Ugo Bassi 58/B, Padua 35121, Italy
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3
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Delfi M, Leone S, Emendato A, Ami D, Borriello M, Natalello A, Iannuzzi C, Picone D. Understanding the self-assembly pathways of a single chain variant of monellin: A first step towards the design of sweet nanomaterials. Int J Biol Macromol 2020; 152:21-29. [PMID: 32088237 DOI: 10.1016/j.ijbiomac.2020.02.229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/19/2020] [Accepted: 02/20/2020] [Indexed: 12/20/2022]
Abstract
Peptides and proteins possess an inherent tendency to self-assemble, prompting the formation of amyloid aggregates from their soluble and functional states. Amyloids are linked to many devastating diseases, but self-assembling proteins can also represent formidable tools to produce new and sustainable biomaterials for biomedical and biotechnological applications. The mechanism of fibrillar aggregation, which influences the morphology and the properties of the protein aggregates, depend on factors such as pH, ionic strength, temperature, agitation, and protein concentration. We have here used intensive mechanical agitation, with or without beads, to prompt the aggregation of the single-chain derivative of the plant protein monellin, named MNEI, which is a well characterized sweet protein. Transmission electron microscopy confirmed the formation of fibrils several micrometers long, morphologically different from the previously characterized fibers of MNEI. Changes in the protein secondary structures during the aggregation process were monitored by Fourier transform infrared spectroscopy, which detected differences in the conformation of the final aggregates obtained under mechanical agitation. Moreover, soluble oligomers could be detected in the early phases of aggregation by polyacrylamide gel-electrophoresis. These findings emphasize the existence of multiple pathways of fibrillar aggregation for MNEI, which could be exploited for the design of innovative protein-based biomaterials.
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Affiliation(s)
- Masoud Delfi
- Department of Chemical Sciences, University of Naples "Federico II", Complesso Universitario Monte S. Angelo, Via Cintia, 80126 Napoli, Italy
| | - Serena Leone
- Department of Chemical Sciences, University of Naples "Federico II", Complesso Universitario Monte S. Angelo, Via Cintia, 80126 Napoli, Italy
| | - Alessandro Emendato
- Department of Chemical Sciences, University of Naples "Federico II", Complesso Universitario Monte S. Angelo, Via Cintia, 80126 Napoli, Italy
| | - Diletta Ami
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | - Margherita Borriello
- Department of Precision Medicine, University of Campania "L. Vanvitelli", Via L. De Crecchio 7, 80138 Naples, Italy
| | - Antonino Natalello
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | - Clara Iannuzzi
- Department of Precision Medicine, University of Campania "L. Vanvitelli", Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Delia Picone
- Department of Chemical Sciences, University of Naples "Federico II", Complesso Universitario Monte S. Angelo, Via Cintia, 80126 Napoli, Italy.
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4
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Donnarumma F, Leone S, Delfi M, Emendato A, Ami D, Laurents DV, Natalello A, Spadaccini R, Picone D. Probing structural changes during amyloid aggregation of the sweet protein MNEI. FEBS J 2019; 287:2808-2822. [DOI: 10.1111/febs.15168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/20/2019] [Accepted: 12/05/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Federica Donnarumma
- Department of Chemical Sciences University of Naples ‘Federico II’ Napoli Italy
| | - Serena Leone
- Department of Chemical Sciences University of Naples ‘Federico II’ Napoli Italy
| | - Masoud Delfi
- Department of Chemical Sciences University of Naples ‘Federico II’ Napoli Italy
| | - Alessandro Emendato
- Department of Chemical Sciences University of Naples ‘Federico II’ Napoli Italy
| | - Diletta Ami
- Department of Biotechnology and Biosciences University of Milano‐Bicocca Italy
| | - Douglas V. Laurents
- Institute of Physical Chemistry ‘Rocasolano’ Consejo Superior de Investigaciones Científicas Madrid Spain
| | - Antonino Natalello
- Department of Biotechnology and Biosciences University of Milano‐Bicocca Italy
| | - Roberta Spadaccini
- Department of Science and Technology Università degli Studi del Sannio Benevento Italy
| | - Delia Picone
- Department of Chemical Sciences University of Naples ‘Federico II’ Napoli Italy
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5
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Weiffert T, Linse S. Protein stabilization with retained function of monellin using a split GFP system. Sci Rep 2018; 8:12763. [PMID: 30143736 PMCID: PMC6109104 DOI: 10.1038/s41598-018-31177-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 08/10/2018] [Indexed: 11/09/2022] Open
Abstract
Sweet proteins are an unexploited resource in the search for non-carbohydrate sweeteners mainly due to their low stability towards heating. Variants of the sweet protein monellin, with increased stability, were derived by an in vivo screening method based on the thermodynamic linkage between fragment complementation and protein stability. This approach depends on the correlation between mutational effects on the affinity between protein fragments and the stability of the intact protein. By linking the two fragments of monellin to the split GFP (green fluorescent protein) system, reconstitution of GFP was promoted and moderately fluorescent colonies were obtained. Two separate random libraries were produced for the monellin chains and the mutant clones were ranked based on fluorescence intensity. Mutants with increased affinity between the fragments, and subsequently increased stability, caused increased fluorescence intensity of split GFP. Single chain monellin variants of the top-ranked mutants for each chain, S76Y in the A-chain and W3C + R39G in the B-chain and all combinations thereof, were expressed and the increase in stability was verified by temperature denaturation studies using circular dichroism spectroscopy. Functionality studies showed that mutant S76Y has retained sweetness and has potential use within the food industry.
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Affiliation(s)
- Tanja Weiffert
- Department of Biochemistry and Structural Biology, Chemical Centre, Lund University, SE221 00, Lund, Sweden.
| | - Sara Linse
- Department of Biochemistry and Structural Biology, Chemical Centre, Lund University, SE221 00, Lund, Sweden
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7
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pH driven fibrillar aggregation of the super-sweet protein Y65R-MNEI: A step-by-step structural analysis. Biochim Biophys Acta Gen Subj 2018; 1862:808-815. [DOI: 10.1016/j.bbagen.2017.12.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 12/14/2017] [Accepted: 12/22/2017] [Indexed: 11/22/2022]
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8
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Mascarenhas NM, Terse VL, Gosavi S. Intrinsic Disorder in a Well-Folded Globular Protein. J Phys Chem B 2018; 122:1876-1884. [PMID: 29304275 DOI: 10.1021/acs.jpcb.7b12546] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The folded structure of the heterodimeric sweet protein monellin mimics single-chain proteins with topology β1-α1-β2-β3-β4-β5 (chain A: β3-β4-β5; chain B: β1-α1-β2). Furthermore, like naturally occurring single-chain proteins of a similar size, monellin folds cooperatively with no detectable intermediates. However, the two monellin chains, A and B, are marginally structured in isolation and fold only upon binding to each other. Thus, monellin presents a unique opportunity to understand the design of intrinsically disordered proteins that fold upon binding. Here, we study the folding of a single-chain variant of monellin (scMn) using simulations of an all heavy-atom structure-based model. These simulations can explain mechanistic details derived from scMn experiments performed using several different structural probes. scMn folds cooperatively in our structure-based simulations, as is also seen in experiments. We find that structure formation near the transition-state ensemble of scMn is not uniformly distributed but is localized to a hairpin-like structure which contains one strand from each chain (β2, β3). Thus, the sequence and the underlying energetics of heterodimeric monellin promote the early formation of the interchain interface (β2-β3). By studying computational scMn mutants whose "interchain" interactions are deleted, we infer that this energy distribution allows the two protein chains to remain largely disordered when this interface is not folded. From these results, we suggest that cutting the protein backbone of a globular protein between residues which lie within its folding nucleus may be one way to construct two disordered fragments which fold upon binding.
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Affiliation(s)
| | - Vishram L Terse
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research , Bangalore 560065, India
| | - Shachi Gosavi
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research , Bangalore 560065, India
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9
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Miele NA, Cabisidan EK, Blaiotta G, Leone S, Masi P, Di Monaco R, Cavella S. Rheological and sensory performance of a protein-based sweetener (MNEI), sucrose, and aspartame in yogurt. J Dairy Sci 2017; 100:9539-9550. [DOI: 10.3168/jds.2017-12894] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 07/09/2017] [Indexed: 11/19/2022]
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10
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Mascarenhas NM, Gosavi S. Understanding protein domain-swapping using structure-based models of protein folding. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 128:113-120. [PMID: 27867057 PMCID: PMC7127520 DOI: 10.1016/j.pbiomolbio.2016.09.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Revised: 09/05/2016] [Accepted: 09/26/2016] [Indexed: 02/05/2023]
Abstract
In domain-swapping, two or more identical protein monomers exchange structural elements and fold into dimers or multimers whose units are structurally similar to the original monomer. Domain-swapping is of biotechnological interest because inhibiting domain-swapping can reduce disease-causing fibrillar protein aggregation. To achieve such inhibition, it is important to understand both the energetics that stabilize the domain-swapped structure and the protein dynamics that enable the swapping. Structure-based models (SBMs) encode the folded structure of the protein in their potential energy functions. SBMs have been successfully used to understand diverse aspects of monomer folding. Symmetrized SBMs model interactions between two identical protein chains using only intra-monomer interactions. Molecular dynamics simulations of such symmetrized SBMs have been used to correctly predict the domain-swapped structure and to understand the mechanism of domain-swapping. Here, we review such models and illustrate that monomer topology determines key aspects of domain-swapping. However, in some proteins, specifics of local energetic interactions modulate domain-swapping and these need to be added to the symmetrized SBMs. We then summarize some general principles of the mechanism of domain-swapping that emerge from the symmetrized SBM simulations. Finally, using our own results, we explore how symmetrized SBMs could be used to design domain-swapping in proteins.
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Affiliation(s)
- Nahren Manuel Mascarenhas
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Shachi Gosavi
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India.
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11
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Spadaccini R, Leone S, Rega MF, Richter C, Picone D. Influence of pH on the structure and stability of the sweet protein MNEI. FEBS Lett 2016; 590:3681-3689. [DOI: 10.1002/1873-3468.12437] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/15/2016] [Accepted: 09/16/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Roberta Spadaccini
- Dipartimento di Scienze e Tecnologie; Università del Sannio; Benevento Italy
| | - Serena Leone
- Dipartimento di Scienze Chimiche; Università di Napoli Federico II; Naples Italy
| | | | | | - Delia Picone
- Dipartimento di Scienze Chimiche; Università di Napoli Federico II; Naples Italy
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12
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Mascarenhas NM, Gosavi S. Protein Domain-Swapping Can Be a Consequence of Functional Residues. J Phys Chem B 2016; 120:6929-38. [PMID: 27331242 DOI: 10.1021/acs.jpcb.6b03968] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Monomer topology has been implicated in domain-swapping, a potential first step on the route to disease-causing protein aggregation. Despite having the same topology (β1-α1-β2-β3-β4-β5), the cysteine protease inhibitor stefin-B domain swaps more readily than a single-chain variant of the heterodimeric sweet protein monellin (scMn). Here, we computationally study the folding of stefin-B and scMn in order to understand the molecular basis for the difference in their domain-swapping propensities. In agreement with experiments, our structure-based simulations show that scMn folds cooperatively without the population of an intermediate while stefin-B populates an equilibrium intermediate state. Since the simulation intermediate has only one domain structured (β3-β4-β5), it can directly lead to domain-swapping. Using computational variants of stefin-B, we show that the population of this intermediate is caused by regions of stefin-B that have been implicated in protease inhibition. We also find that the protease-binding regions are located on two structural elements and localized in space. In contrast, the residues that contribute to the sweetness of monellin are not localized to a few structural elements but are distributed over the protein fold. We conclude that the distributed functional residues of monellin do not induce large local perturbations in the protein structure, eliminating the formation of folding intermediates and in turn domain-swapping. On the other hand, the localized protease-binding regions of stefin-B promote the formation of a folding intermediate which can lead to domain-swapping. Thus, domain-swapping can be a direct consequence of the constraints that function imposes on the protein structure.
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Affiliation(s)
- Nahren Manuel Mascarenhas
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research , Bangalore 560065, India
| | - Shachi Gosavi
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research , Bangalore 560065, India
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Leone S, Picone D. Molecular Dynamics Driven Design of pH-Stabilized Mutants of MNEI, a Sweet Protein. PLoS One 2016; 11:e0158372. [PMID: 27340829 PMCID: PMC4920389 DOI: 10.1371/journal.pone.0158372] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/14/2016] [Indexed: 11/18/2022] Open
Abstract
MNEI is a single chain derivative of monellin, a plant protein that can interact with the human sweet taste receptor, being therefore perceived as sweet. This unusual physiological activity makes MNEI a potential template for the design of new sugar replacers for the food and beverage industry. Unfortunately, applications of MNEI have been so far limited by its intrinsic sensitivity to some pH and temperature conditions, which could occur in industrial processes. Changes in physical parameters can, in fact, lead to irreversible protein denaturation, as well as aggregation and precipitation. It has been previously shown that the correlation between pH and stability in MNEI derives from the presence of a single glutamic residue in a hydrophobic pocket of the protein. We have used molecular dynamics to study the consequences, at the atomic level, of the protonation state of such residue and have identified the network of intramolecular interactions responsible for MNEI stability at acidic pH. Based on this information, we have designed a pH-independent, stabilized mutant of MNEI and confirmed its increased stability by both molecular modeling and experimental techniques.
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Affiliation(s)
- Serena Leone
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy
| | - Delia Picone
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy
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14
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Abstract
Cystatins are small proteins, typically composed of 100-120 amino acids, which together with similar proteins devoid of inhibitory properties, belong to a cystatin 'superfamily'. Cystatins can do more than just inhibit proteases: two important aspects described here are aggregation properties linked to misfolding diseases and the unique ability of monellin, a plant cystatin, to elicit sweet taste. The explanation of the puzzling phenomenon of 'sweet proteins' required an in-depth structural study of monellin, also regarding the causes of the high thermal stability of its single chain structure. The detailed mechanisms by which cystatins aggregate could be relevant in the study of misfolding diseases involving cystatins. They are reviewed here with emphasis on 3D domain swapping, typical of aggregating cystatins. While studying monellin, we noticed that it aggregates in a conventional way, probably through the cross-β spine mechanism. However, several cystatins derived from oryzacystatin_I to emulate the taste behavior of monellin aggregate via different mechanisms.
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15
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Rega MF, Di Monaco R, Leone S, Donnarumma F, Spadaccini R, Cavella S, Picone D. Design of sweet protein based sweeteners: hints from structure-function relationships. Food Chem 2014; 173:1179-86. [PMID: 25466141 DOI: 10.1016/j.foodchem.2014.10.151] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 10/01/2014] [Accepted: 10/30/2014] [Indexed: 11/29/2022]
Abstract
Sweet proteins represent a class of natural molecules, which are extremely interesting regarding their potential use as safe low-calories sweeteners for individuals who need to control sugar intake, such as obese or diabetic subjects. Punctual mutations of amino acid residues of MNEI, a single chain derivative of the natural sweet protein monellin, allow the modulation of its taste. In this study we present a structural and functional comparison between MNEI and a sweeter mutant Y65R, containing an extra positive charge on the protein surface, in conditions mimicking those of typical beverages. Y65R exhibits superior sweetness in all the experimental conditions tested, has a better solubility at mild acidic pH and preserves a significant thermal stability in a wide range of pH conditions, although slightly lower than MNEI. Our findings confirm the advantages of structure-guided protein engineering to design improved low-calorie sweeteners and excipients for food and pharmaceutical preparations.
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Affiliation(s)
- Michele Fortunato Rega
- Department of Chemical Sciences, University of Naples Federico II, via Cintia, 80126 Naples, Italy
| | - Rossella Di Monaco
- Food Science and Agricultural Department, University of Naples - Federico II, Italy; Centre for Food Innovation and Development, University of Naples, Portici, Italy
| | - Serena Leone
- Department of Chemical Sciences, University of Naples Federico II, via Cintia, 80126 Naples, Italy
| | - Federica Donnarumma
- Department of Chemical Sciences, University of Naples Federico II, via Cintia, 80126 Naples, Italy
| | - Roberta Spadaccini
- Department of Science and Technology, University of Sannio, 82100 Benevento, Italy
| | - Silvana Cavella
- Food Science and Agricultural Department, University of Naples - Federico II, Italy; Centre for Food Innovation and Development, University of Naples, Portici, Italy
| | - Delia Picone
- Department of Chemical Sciences, University of Naples Federico II, via Cintia, 80126 Naples, Italy.
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16
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Sabareesan AT, Udgaonkar JB. Amyloid Fibril Formation by the Chain B Subunit of Monellin Occurs by a Nucleation-Dependent Polymerization Mechanism. Biochemistry 2014; 53:1206-17. [DOI: 10.1021/bi401467p] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A. T. Sabareesan
- National Centre for Biological
Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Jayant B. Udgaonkar
- National Centre for Biological
Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
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17
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The unique structure of Haemophilus influenzae protein E reveals multiple binding sites for host factors. Infect Immun 2012; 81:801-14. [PMID: 23275089 DOI: 10.1128/iai.01111-12] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Haemophilus influenzae protein E (PE) is a multifunctional adhesin involved in direct interactions with lung epithelial cells and host proteins, including plasminogen and the extracellular matrix proteins vitronectin and laminin. We recently crystallized PE and successfully collected X-ray diffraction data at 1.8 Å. Here, we solved the structure of a recombinant version of PE and analyzed different functional regions. It is a dimer in solution and in the asymmetric unit of the crystals. The dimer has a structure that resembles a flattened β-barrel. It is, however, not a true β-barrel, as there are differences in both the hydrogen-bonding pattern and the shape. Each monomer consisted of a 6-stranded antiparallel β-sheet with a rigid α-helix at the C terminus tethered to the concave side of the sheet by a disulfide bridge. The laminin/plasminogen binding region (residues 41 to 68) is exposed, while the vitronectin binding region (residues 84 to 108) is partially accessible in the dimer. The dimerized PE explains the simultaneous interaction with laminin and vitronectin. In addition, we found this unique adhesin to be present in many bacterial genera of the family Pasteurellaceae and also orthologues in other, unrelated species (Enterobacter cloacae and Listeria monocytogenes). Peptides corresponding to the surface-exposed regions PE 24 to 37, PE 74 to 89, and PE 134 to 156 were immunogenic in the mouse. Importantly, these peptide-based antibodies also recognized PE at the bacterial surface. Taken together, our detailed structure of PE explains how this important virulence factor of H. influenzae simultaneously interacts with host vitronectin, laminin, or plasminogen, promoting bacterial pathogenesis.
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18
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Aghera N, Udgaonkar JB. Heterologous expression, purification and characterization of heterodimeric monellin. Protein Expr Purif 2011; 76:248-53. [DOI: 10.1016/j.pep.2010.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 10/26/2010] [Accepted: 11/03/2010] [Indexed: 11/29/2022]
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