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Transmembrane protein rotaxanes reveal kinetic traps in the refolding of translocated substrates. Commun Biol 2020; 3:159. [PMID: 32246060 PMCID: PMC7125113 DOI: 10.1038/s42003-020-0840-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 02/20/2020] [Indexed: 01/22/2023] Open
Abstract
Understanding protein folding under conditions similar to those found in vivo remains challenging. Folding occurs mainly vectorially as a polypeptide emerges from the ribosome or from a membrane translocon. Protein folding during membrane translocation is particularly difficult to study. Here, we describe a single-molecule method to characterize the folded state of individual proteins after membrane translocation, by monitoring the ionic current passing through the pore. We tag both N and C termini of a model protein, thioredoxin, with biotinylated oligonucleotides. Under an electric potential, one of the oligonucleotides is pulled through a α-hemolysin nanopore driving the unfolding and translocation of the protein. We trap the protein in the nanopore as a rotaxane-like complex using streptavidin stoppers. The protein is subjected to cycles of unfolding-translocation-refolding switching the voltage polarity. We find that the refolding pathway after translocation is slower than in bulk solution due to the existence of kinetic traps. Feng et al address the technical challenge of monitoring the protein folding during membrane translocation. Using thioredoxin as a model and with electric potential driving its translocation through single a-hemolysin nanopore, they observe that after translocation, folding is slower than in bulk due to existence of kinetic traps.
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2
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Gotte G, Menegazzi M. Biological Activities of Secretory RNases: Focus on Their Oligomerization to Design Antitumor Drugs. Front Immunol 2019; 10:2626. [PMID: 31849926 PMCID: PMC6901985 DOI: 10.3389/fimmu.2019.02626] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/22/2019] [Indexed: 12/11/2022] Open
Abstract
Ribonucleases (RNases) are a large number of enzymes gathered into different bacterial or eukaryotic superfamilies. Bovine pancreatic RNase A, bovine seminal BS-RNase, human pancreatic RNase 1, angiogenin (RNase 5), and amphibian onconase belong to the pancreatic type superfamily, while binase and barnase are in the bacterial RNase N1/T1 family. In physiological conditions, most RNases secreted in the extracellular space counteract the undesired effects of extracellular RNAs and become protective against infections. Instead, if they enter the cell, RNases can digest intracellular RNAs, becoming cytotoxic and having advantageous effects against malignant cells. Their biological activities have been investigated either in vitro, toward a number of different cancer cell lines, or in some cases in vivo to test their potential therapeutic use. However, immunogenicity or other undesired effects have sometimes been associated with their action. Nevertheless, the use of RNases in therapy remains an appealing strategy against some still incurable tumors, such as mesothelioma, melanoma, or pancreatic cancer. The RNase inhibitor (RI) present inside almost all cells is the most efficacious sentry to counteract the ribonucleolytic action against intracellular RNAs because it forms a tight, irreversible and enzymatically inactive complex with many monomeric RNases. Therefore, dimerization or multimerization could represent a useful strategy for RNases to exert a remarkable cytotoxic activity by evading the interaction with RI by steric hindrance. Indeed, the majority of the mentioned RNases can hetero-dimerize with antibody derivatives, or even homo-dimerize or multimerize, spontaneously or artificially. This can occur through weak interactions or upon introducing covalent bonds. Immuno-RNases, in particular, are fusion proteins representing promising drugs by combining high target specificity with easy delivery in tumors. The results concerning the biological features of many RNases reported in the literature are described and discussed in this review. Furthermore, the activities displayed by some RNases forming oligomeric complexes, the mechanisms driving toward these supramolecular structures, and the biological rebounds connected are analyzed. These aspects are offered with the perspective to suggest possible efficacious therapeutic applications for RNases oligomeric derivatives that could contemporarily lack, or strongly reduce, immunogenicity and other undesired side-effects.
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Affiliation(s)
- Giovanni Gotte
- Biological Chemistry Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Marta Menegazzi
- Biological Chemistry Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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3
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Esposito L, Donnarumma F, Ruggiero A, Leone S, Vitagliano L, Picone D. Structure, stability and aggregation propensity of a Ribonuclease A-Onconase chimera. Int J Biol Macromol 2019; 133:1125-1133. [PMID: 31026530 DOI: 10.1016/j.ijbiomac.2019.04.164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/10/2019] [Accepted: 04/23/2019] [Indexed: 01/05/2023]
Abstract
Structural roles of loop regions are frequently overlooked in proteins. Nevertheless, they may be key players in the definition of protein topology and in the self-assembly processes occurring through domain swapping. We here investigate the effects on structure and stability of replacing the loop connecting the last two β-strands of RNase A with the corresponding region of the more thermostable Onconase. The crystal structure of this chimeric variant (RNaseA-ONC) shows that its terminal loop size better adheres to the topological rules for the design of stabilized proteins, proposed by Baker and coworkers [43]. Indeed, RNaseA-ONC displays a thermal stability close to that of RNase A, despite the lack of Pro at position 114, which, due to its propensity to favor a cis peptide bond, has been identified as an important stabilizing factor of the native protein. Accordingly, RNaseA-ONC is significantly more stable than RNase A variants lacking Pro114; RNaseA-ONC also displays a higher propensity to form oligomers in native conditions when compared to either RNase A or Onconase. This finding demonstrates that modifications of terminal loops should to be carefully controlled in terms of size and sequence to avoid unwanted and/or potentially harmful aggregation processes.
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Affiliation(s)
- Luciana Esposito
- CNR Istituto di Biostrutture e Bioimmagini, Via Mezzocannone 16, I-80134 Napoli, Italy.
| | - Federica Donnarumma
- Dipartimento di Scienze Chimiche, Università degli Studi di Napoli "Federico II", Via Cintia, I-80126 Napoli, Italy
| | - Alessia Ruggiero
- CNR Istituto di Biostrutture e Bioimmagini, Via Mezzocannone 16, I-80134 Napoli, Italy
| | - Serena Leone
- Dipartimento di Scienze Chimiche, Università degli Studi di Napoli "Federico II", Via Cintia, I-80126 Napoli, Italy
| | - Luigi Vitagliano
- CNR Istituto di Biostrutture e Bioimmagini, Via Mezzocannone 16, I-80134 Napoli, Italy.
| | - Delia Picone
- Dipartimento di Scienze Chimiche, Università degli Studi di Napoli "Federico II", Via Cintia, I-80126 Napoli, Italy.
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4
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Lussi C, Sauter KS, Schweizer M. Homodimerisation-independent cleavage of dsRNA by a pestiviral nicking endoribonuclease. Sci Rep 2018; 8:8226. [PMID: 29844335 PMCID: PMC5974291 DOI: 10.1038/s41598-018-26557-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 05/09/2018] [Indexed: 12/12/2022] Open
Abstract
The glycoprotein Erns plays a central role in the biology of the pestivirus bovine viral diarrhea virus (BVDV). This soluble endonuclease mediates the escape from an interferon (IFN) response in the infected fetus, thereby permitting the establishment of persistent infection. Viral single-stranded (ss) and double-stranded (ds) RNA act as potent IFN inducing signals and we previously showed that Erns efficiently cleaves these substrates, thereby inhibiting an IFN response that is crucial for successful fetal infection. Considering that a large variety of RNases and DNases require dimerisation to cleave double-stranded substrates, the activity of Erns against dsRNA was postulated to depend on homodimer formation mediated by disulfide bonds involving residue Cys171. Here, we show that monomeric Erns is equally able to cleave dsRNA and to inhibit dsRNA-induced IFN synthesis as the wild-type form. Furthermore, both forms were able to degrade RNA within a DNA/RNA- as well as within a methylated RNA/RNA-hybrid, with the DNA and the methylated RNA strand being resistant to degradation. These results support our model that Erns acts as 'nicking endoribonuclease' degrading ssRNA within double-stranded substrates. This efficiently prevents the activation of IFN and helps to maintain a state of innate immunotolerance in persistently infected animals.
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Affiliation(s)
- Carmela Lussi
- Institute of Virology and Immunology, Laenggass-Str. 122, CH-3001, Bern, Switzerland.,Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Kay-Sara Sauter
- Institute of Virology and Immunology, Laenggass-Str. 122, CH-3001, Bern, Switzerland.,Department of Clinical Research, Faculty of Medicine, University of Bern, CH-3010, Bern, Switzerland
| | - Matthias Schweizer
- Institute of Virology and Immunology, Laenggass-Str. 122, CH-3001, Bern, Switzerland. .,Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
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5
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Fagagnini A, Montioli R, Caloiu A, Ribó M, Laurents DV, Gotte G. Extensive deamidation of RNase A inhibits its oligomerization through 3D domain swapping. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1865:76-87. [PMID: 27783927 DOI: 10.1016/j.bbapap.2016.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 10/03/2016] [Accepted: 10/20/2016] [Indexed: 12/27/2022]
Abstract
Bovine pancreatic ribonuclease A (RNase A) is the monomeric prototype of the so-called secretory 'pancreatic-type' RNase super-family. Like the naturally domain-swapped dimeric bovine seminal variant, BS-RNase, and its glycosylated RNase B isoform, RNase A forms N- and C-terminal 3D domain-swapped oligomers after lyophilization from acid solutions, or if subjected to thermal denaturation at high protein concentration. All mentioned RNases can undergo deamidation at Asn67, forming Asp or isoAsp derivatives that modify the protein net charge and consequently its enzymatic activity. In addition, deamidation slightly affects RNase B self-association through the 3D domain swapping (3D-DS) mechanism. We report here the influence of extensive deamidation on RNase A tendency to oligomerize through 3D-DS. In particular, deamidation of Asn67 alone slightly decreases the propensity of the protein to oligomerize, with the Asp derivative being less affected than the isoAsp one. Contrarily, the additional Asp and/or isoAsp conversion of residues other than N67 almost nullifies RNase A oligomerization capability. In addition, Gln deamidation, although less kinetically favorable, may affect RNase A self-association. Using 2D and 3D NMR we identified the Asn/Gln residues most prone to undergo deamidation. Together with CD spectroscopy, NMR also indicates that poly-deamidated RNase A generally maintains its native tertiary structure. Again, we investigated in silico the effect of the residues undergoing deamidation on RNase A dimers structures. Finally, the effect of deamidation on RNase A oligomerization is discussed in comparison with studies on deamidation-prone proteins involved in amyloid formation.
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Affiliation(s)
- Andrea Fagagnini
- Dipartimento di Neuroscienze, Biomedicina e del Movimento, Sezione di Chimica Biologica, Università degli Studi di Verona, Strada Le Grazie 8, I-37134 Verona, Italy
| | - Riccardo Montioli
- Dipartimento di Neuroscienze, Biomedicina e del Movimento, Sezione di Chimica Biologica, Università degli Studi di Verona, Strada Le Grazie 8, I-37134 Verona, Italy
| | - Andra Caloiu
- Dipartimento di Neuroscienze, Biomedicina e del Movimento, Sezione di Chimica Biologica, Università degli Studi di Verona, Strada Le Grazie 8, I-37134 Verona, Italy
| | - Marc Ribó
- Laboratori d'Enginyeria de Proteïnes, Departament de Biologia, Facultat de Ciències, Universitat de Girona, 17071, y Institut d'Investigació Biomèdica de Girona Josep Trueta, (IdIBGi), Girona, Spain
| | - Douglas V Laurents
- Instituto de Quimica Fisica "Rocasolano" (C.S.I.C.), Serrano 119, E-28006 Madrid, Spain
| | - Giovanni Gotte
- Dipartimento di Neuroscienze, Biomedicina e del Movimento, Sezione di Chimica Biologica, Università degli Studi di Verona, Strada Le Grazie 8, I-37134 Verona, Italy.
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Abstract
Transport of newly synthesized proteins from the endoplasmic reticulum (ER) to the Golgi complex is highly selective. As a general rule, such transport is limited to soluble and membrane-associated secretory proteins that have reached properly folded and assembled conformations. To secure the efficiency, fidelity, and control of this crucial transport step, cells use a combination of mechanisms. The mechanisms are based on selective retention of proteins in the ER to prevent uptake into transport vesicles, on selective capture of proteins in COPII carrier vesicles, on inclusion of proteins in these vesicles by default as part of fluid and membrane bulk flow, and on selective retrieval of proteins from post-ER compartments by retrograde vesicle transport.
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Affiliation(s)
- Charles Barlowe
- Biochemistry Department, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755;
| | - Ari Helenius
- Institute of Biochemistry, ETH Zurich, Zurich CH-8093, Switzerland
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Suyama K, Hori M, Gomi K, Shintani T. Fusion of an intact secretory protein permits a misfolded protein to exit from the endoplasmic reticulum in yeast. Biosci Biotechnol Biochem 2014; 78:49-59. [PMID: 25036483 DOI: 10.1080/09168451.2014.877185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Upon exit from the endoplasmic reticulum (ER), the nascent polypeptides of secretory proteins undergo sorting events. If properly folded, they are directly or indirectly recognized by the coat proteins of budding vesicles for forward transport, while unfolded or misfolded proteins are retained in the ER by a quality control mechanism. To gain insight into the interplay between ER export and ER quality control, we fused a secretory protein invertase to the C-terminus of mutated carboxypeptidase Y (CPY*), a model ER-associated degradation (ERAD) substrate in Saccharomyces cerevisiae. This substrate, designated CPY*-Inv, was largely exported from the ER, although it was fully recognized by the ERAD-related lectin, Yos9, and hence degraded by the ERAD when it remained in the ER. CPY*-Inv relied primarily on the p24 complex, a putative ER export receptor for invertase, for escape from ERAD, suggesting that the ERAD and the ER export of soluble secretory proteins are competitive.
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Affiliation(s)
- Kengo Suyama
- a Department of Bioindustrial Informatics and Genomics, Graduate School of Agricultural Science , Tohoku University , Sendai , Japan
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8
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Structural and functional relationships of natural and artificial dimeric bovine ribonucleases: new scaffolds for potential antitumor drugs. FEBS Lett 2013; 587:3601-8. [PMID: 24113657 DOI: 10.1016/j.febslet.2013.09.038] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 08/23/2013] [Accepted: 09/24/2013] [Indexed: 11/20/2022]
Abstract
Protein aggregation via 3D domain swapping is a complex mechanism which can lead to the acquisition of new biological, benign or also malignant functions, such as amyloid deposits. In this context, RNase A represents a fascinating model system, since by dislocating different polypeptide chain regions, it forms many diverse oligomers. No other protein displays such a large number of different quaternary structures. Here we report a comparative structural analysis between natural and artificial RNase A dimers and bovine seminal ribonuclease, a natively dimeric RNase with antitumor activity, with the aim to design RNase A derivatives with improved pharmacological potential.
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9
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Abstract
In this article, we will cover the folding of proteins in the lumen of the endoplasmic reticulum (ER), including the role of three types of covalent modifications: signal peptide removal, N-linked glycosylation, and disulfide bond formation, as well as the function and importance of resident ER folding factors. These folding factors consist of classical chaperones and their cochaperones, the carbohydrate-binding chaperones, and the folding catalysts of the PDI and proline cis-trans isomerase families. We will conclude with the perspective of the folding protein: a comparison of characteristics and folding and exit rates for proteins that travel through the ER as clients of the ER machinery.
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Affiliation(s)
- Ineke Braakman
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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10
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Double domain swapping in bovine seminal RNase: formation of distinct N- and C-swapped tetramers and multimers with increasing biological activities. PLoS One 2012; 7:e46804. [PMID: 23071641 PMCID: PMC3469567 DOI: 10.1371/journal.pone.0046804] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 09/10/2012] [Indexed: 12/24/2022] Open
Abstract
Bovine seminal (BS) RNase, the unique natively dimeric member of the RNase super-family, represents a special case not only for its additional biological actions but also for the singular features of 3D domain swapping. The native enzyme is indeed a mixture of two isoforms: M = M, a dimer held together by two inter-subunit disulfide bonds, and MxM, 70% of the total, which, besides the two mentioned disulfides, is additionally stabilized by the swapping of its N-termini. When lyophilized from 40% acetic acid, BS-RNase oligomerizes as the super-family proto-type RNase A does. In this paper, we induced BS-RNase self-association and analyzed the multimers by size-exclusion chromatography, cross-linking, electrophoresis, mutagenesis, dynamic light scattering, molecular modelling. Finally, we evaluated their enzymatic and cytotoxic activities. Several BS-RNase domain-swapped oligomers were detected, including two tetramers, one exchanging only the N-termini, the other being either N- or C-swapped. The C-swapping event, confirmed by results on a BS-K113N mutant, has been firstly seen in BS-RNase here, and probably stabilizes also multimers larger than tetramers. Interestingly, all BS-RNase oligomers are more enzymatically active than the native dimer and, above all, they display a cytotoxic activity that definitely increases with the molecular weight of the multimers. This latter feature, to date unknown for BS-RNase, suggests again that the self-association of RNases strongly modulates their biological and potentially therapeutic properties.
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11
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Spadaccini R, Ercole C, Gentile MA, Sanfelice D, Boelens R, Wechselberger R, Batta G, Bernini A, Niccolai N, Picone D. NMR studies on structure and dynamics of the monomeric derivative of BS-RNase: new insights for 3D domain swapping. PLoS One 2012; 7:e29076. [PMID: 22253705 PMCID: PMC3257227 DOI: 10.1371/journal.pone.0029076] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 11/20/2011] [Indexed: 11/18/2022] Open
Abstract
Three-dimensional domain swapping is a common phenomenon in pancreatic-like ribonucleases. In the aggregated state, these proteins acquire new biological functions, including selective cytotoxicity against tumour cells. RNase A is able to dislocate both N- and C-termini, but usually this process requires denaturing conditions. In contrast, bovine seminal ribonuclease (BS-RNase), which is a homo-dimeric protein sharing 80% of sequence identity with RNase A, occurs natively as a mixture of swapped and unswapped isoforms. The presence of two disulfides bridging the subunits, indeed, ensures a dimeric structure also to the unswapped molecule. In vitro, the two BS-RNase isoforms interconvert under physiological conditions. Since the tendency to swap is often related to the instability of the monomeric proteins, in these paper we have analysed in detail the stability in solution of the monomeric derivative of BS-RNase (mBS) by a combination of NMR studies and Molecular Dynamics Simulations. The refinement of NMR structure and relaxation data indicate a close similarity with RNase A, without any evidence of aggregation or partial opening. The high compactness of mBS structure is confirmed also by H/D exchange, urea denaturation, and TEMPOL mapping of the protein surface. The present extensive structural and dynamic investigation of (monomeric) mBS did not show any experimental evidence that could explain the known differences in swapping between BS-RNase and RNase A. Hence, we conclude that the swapping in BS-RNase must be influenced by the distinct features of the dimers, suggesting a prominent role for the interchain disulfide bridges.
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Affiliation(s)
- Roberta Spadaccini
- Dipartimento di Scienze Biologiche ed Ambientali, Università del Sannio, Benevento, Italy
| | - Carmine Ercole
- Dipartimento di Chimica, Università degli Studi di Napoli “Federico II”, Napoli, Italy
| | - Maria A. Gentile
- Dipartimento di Chimica, Università degli Studi di Napoli “Federico II”, Napoli, Italy
| | - Domenico Sanfelice
- Dipartimento di Chimica, Università degli Studi di Napoli “Federico II”, Napoli, Italy
| | - Rolf Boelens
- Department of NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands
| | - Rainer Wechselberger
- Department of NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands
| | - Gyula Batta
- Institute of Chemistry, University of Debrecen, Debrecen, Hungary
| | - Andrea Bernini
- Dipartimento di Biotecnologie, Università degli Studi di Siena, Siena, Italy
| | - Neri Niccolai
- Dipartimento di Biotecnologie, Università degli Studi di Siena, Siena, Italy
| | - Delia Picone
- Dipartimento di Chimica, Università degli Studi di Napoli “Federico II”, Napoli, Italy
- * E-mail:
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Tubert P, Laurents DV, Ribó M, Bruix M, Vilanova M, Benito A. Interactions crucial for three-dimensional domain swapping in the HP-RNase variant PM8. Biophys J 2011; 101:459-67. [PMID: 21767499 DOI: 10.1016/j.bpj.2011.06.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 06/08/2011] [Accepted: 06/13/2011] [Indexed: 11/29/2022] Open
Abstract
The structural determinants that are responsible for the formation of higher order associations of folded proteins remain unknown. We have investigated the role on the dimerization process of different residues of a domain-swapped dimer human pancreatic ribonuclease variant. This variant is a good model to study the dimerization and swapping processes because dimer and monomer forms interconvert, are easily isolated, and only one dimeric species is produced. Thus, simple models for the swapping process can be proposed. The dimerization (dissociation constant) and swapping propensity have been studied using different variants with changes in residues that belong to different putative molecular determinants of dimerization. Using NMR spectroscopy, we show that these mutations do not substantially alter the overall conformation and flexibility, but affect the residue level stability. Overall, the most critical residues for the swapping process are those of one subunit that interact with the hinge loop of another one-subunit residue, stabilizing it in a conformation that favors the interchange. Tyr(25), Gln(101), and Pro(19), with Asn(17), Ser(21), and Ser(23), are found to be the most significant; notably, Glu(103) and Arg(104), which were postulated to form salt bridges that would stabilize the dimer, are not critical for dimerization.
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Affiliation(s)
- Pere Tubert
- Laboratori d'Enginyeria de Proteïnes, Departament de Biologia, Facultat de Ciències, Universitat de Girona, Campus de Montilivi, Maria Aurèlia Campmany, 69 E-17071 Girona, Spain
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13
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Vottariello F, Giacomelli E, Frasson R, Pozzi N, De Filippis V, Gotte G. RNase A oligomerization through 3D domain swapping is favoured by a residue located far from the swapping domains. Biochimie 2011; 93:1846-57. [PMID: 21771635 DOI: 10.1016/j.biochi.2011.07.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Accepted: 07/04/2011] [Indexed: 11/27/2022]
Abstract
Bovine pancreatic ribonuclease A forms 3D domain-swapped oligomers by lyophilization from 40% acetic acid solutions or if subjected to various thermally-induced denaturation procedures. Considering that the intrinsic swapping propensity of bovine seminal RNase, the only member of the pancreatic-type RNase super-family that is dimeric in nature, is decreased from 70 to 30% if Arg80 is substituted by Ser (the corresponding residue in native RNase A), we introduced the opposite mutation in position 80 of the pancreatic enzyme. Our aim was to detect if the RNase A tendency to aggregate through domain swapping could increase. Aggregation of the S80R-RNase A mutant was induced either through the 'classic' acetic acid lyophilization, or through a thermally-induced method. The results indicate that the S80R mutant aggregates to a higher extent than the native protein, and that the increase occurs especially through N-terminal swapping. Additional investigations on the dimeric and multimeric species formed indicate that the S80R mutation increases their stability against regression to monomer, and does not significantly change their structural and functional features.
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Affiliation(s)
- Francesca Vottariello
- Dipartimento di Scienze della Vita e della Riproduzione, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, University of Verona, Strada Le Grazie 8, I-37134 Verona, Italy
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