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Kalichuk V, Béhar G, Renodon-Cornière A, Danovski G, Obal G, Barbet J, Mouratou B, Pecorari F. The archaeal "7 kDa DNA-binding" proteins: extended characterization of an old gifted family. Sci Rep 2016; 6:37274. [PMID: 27853299 PMCID: PMC5112516 DOI: 10.1038/srep37274] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 10/27/2016] [Indexed: 01/06/2023] Open
Abstract
The “7 kDa DNA-binding” family, also known as the Sul7d family, is composed of chromatin proteins from the Sulfolobales archaeal order. Among them, Sac7d and Sso7d have been the focus of several studies with some characterization of their properties. Here, we studied eleven other proteins alongside Sac7d and Sso7d under the same conditions. The dissociation constants of the purified proteins for binding to double-stranded DNA (dsDNA) were determined in phosphate-buffered saline at 25 °C and were in the range from 11 μM to 22 μM with a preference for G/C rich sequences. In accordance with the extremophilic origin of their hosts, the proteins were found highly stable from pH 0 to pH 12 and at temperatures from 85.5 °C to 100 °C. Thus, these results validate eight putative “7 kDa DNA-binding” family proteins and show that they behave similarly regarding both their function and their stability among various genera and species. As Sac7d and Sso7d have found numerous uses as molecular biology reagents and artificial affinity proteins, this study also sheds light on even more attractive proteins that will facilitate engineering of novel highly robust reagents.
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Affiliation(s)
- Valentina Kalichuk
- CRCNA, Inserm, CNRS, Université d'Angers, Université de Nantes, Nantes, France.,Université catholique de Louvain, Louvain Drug Research Institute, Advanced Drug Delivery and Biomaterials, Brussels, Belgium
| | - Ghislaine Béhar
- CRCNA, Inserm, CNRS, Université d'Angers, Université de Nantes, Nantes, France
| | | | - Georgi Danovski
- CRCNA, Inserm, CNRS, Université d'Angers, Université de Nantes, Nantes, France
| | - Gonzalo Obal
- Institut Pasteur de Montevideo, Protein Biophysics Unit, Montevideo, Uruguay
| | - Jacques Barbet
- CRCNA, Inserm, CNRS, Université d'Angers, Université de Nantes, Nantes, France
| | - Barbara Mouratou
- CRCNA, Inserm, CNRS, Université d'Angers, Université de Nantes, Nantes, France
| | - Frédéric Pecorari
- CRCNA, Inserm, CNRS, Université d'Angers, Université de Nantes, Nantes, France
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Béhar G, Pacheco S, Maillasson M, Mouratou B, Pecorari F. Switching an anti-IgG binding site between archaeal extremophilic proteins results in Affitins with enhanced pH stability. J Biotechnol 2015; 192 Pt A:123-9. [PMID: 25450641 DOI: 10.1016/j.jbiotec.2014.10.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/28/2014] [Accepted: 10/07/2014] [Indexed: 12/23/2022]
Abstract
As a useful reagent for biotechnological applications, a scaffold protein needs to be as stable as possible to ensure longer lifetimes. We have developed archaeal extremophilic proteins from the “7 kDa DNA-binding” family as scaffolds to derive affinity proteins (Affitins). In this study, we evaluated a rational structure/sequence-guided approach to stabilize an Affitin derived from Sac7d by transferring its human IgG binding site onto the framework of the more thermally stable Sso7d homolog. The chimera obtained was functional, well expressed in Escherichia coli, but less thermally stable than the original Affitin (T(m) = 74.2 °C vs. T(m) = 80.4 °C). Two single mutations described as thermally stabilizing wild type Sso7d were introduced into chimeras. Only the double mutation nearly restored thermal stability (T(m) = 76.9 °C). Interestingly, the chimera and its double mutant were stable from pH 0 up to at least pH 13. Our results show that it is possible to increase further the stability of Affitins toward alkaline conditions (+2 pH units) while conserving their advantageous properties. As Affitins are based on a growing family of homologs from archaeal extremophiles, we conclude that this approach offers new potential for their improvement, which will be useful in demanding biotechnological applications.
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Béhar G, Bellinzoni M, Maillasson M, Paillard-Laurance L, Alzari PM, He X, Mouratou B, Pecorari F. Tolerance of the archaeal Sac7d scaffold protein to alternative library designs: characterization of anti-immunoglobulin G Affitins. Protein Eng Des Sel 2013; 26:267-75. [PMID: 23315487 DOI: 10.1093/protein/gzs106] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Engineered protein scaffolds have received considerable attention as alternatives to antibodies in both basic and applied research, as they can offer superior biophysical properties often associated with a simpler molecular organization. Sac7d has been demonstrated as an effective scaffold for molecular recognition. Here, we used the initial L1 'flat surface' library constructed by randomization of 14 residues, to identify ligands specific for human immunoglobulin G. To challenge the plasticity of the Sac7d protein scaffold, we designed the alternative L2 'flat surface & loops' library whereof only 10 residues are randomized. Representative binders (Affitins) of the two libraries exhibited affinities in the low nanomolar range and were able to recognize different epitopes within human immunoglobulin G. These Affitins were stable up to pH 12 while largely conserving other favorable properties of Sac7d protein, such as high expression yields in Escherichia coli, solubility, thermal stability up to 80.7°C, and acidic stability (pH 0). In agreement with our library designs, mutagenesis study revealed two distinct binding areas, one including loops. Together, our results indicate that the Sac7d scaffold tolerates alternative library designs, which further expands the diversity of Affitins and may provide a general way to create tailored affinity tools for demanding applications.
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Affiliation(s)
- Ghislaine Béhar
- Université de Nantes, UMR CNRS 6204, Ingénierie de la reconnaissance, F-44322 Nantes, France
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Priyakumar UD. Role of Hydrophobic Core on the Thermal Stability of Proteins—Molecular Dynamics Simulations on a Single Point Mutant of Sso7d. J Biomol Struct Dyn 2012; 29:961-71. [DOI: 10.1080/07391102.2012.10507415] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Bernini A, Spiga O, Consonni R, Arosio I, Fusi P, Cirri S, Guagliardi A, Niccolai N. Hydration studies on the archaeal protein Sso7d using NMR measurements and MD simulations. BMC STRUCTURAL BIOLOGY 2011; 11:44. [PMID: 22017970 PMCID: PMC3207888 DOI: 10.1186/1472-6807-11-44] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 10/21/2011] [Indexed: 11/25/2022]
Abstract
Background How proteins approach surrounding molecules is fundamental to our understanding of the specific interactions that occur at the surface of proteins. The enhanced surface accessibility of small molecules such as organic solvents and paramagnetic probes to protein binding sites has been observed; however, the molecular basis of this finding has not been fully established. Recently, it has been suggested that hydration dynamics play a predominant role in controlling the distribution of hot spots on surface of proteins. Results In the present study, the hydration of the archaeal multifunctional protein Sso7d from Solfolobus solfataricus was investigated using a combination of computational and experimental data derived from molecular dynamics simulations and ePHOGSY NMR spectroscopy. Conclusions We obtained a convergent protein hydration landscape that indicated how the shape and stability of the Sso7d hydration shell could modulate the function of the protein. The DNA binding domain overlaps with the protein region involved in chaperon activity and this domain is hydrated only in a very small central region. This localized hydration seems to favor intermolecular approaches from a large variety of ligands. Conversely, high water density was found in surface regions of the protein where the ATP binding site is located, suggesting that surface water molecules play a role in protecting the protein from unspecific interactions.
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Affiliation(s)
- Andrea Bernini
- Dipartimento di Biotecnologie, Università degli Studi di Siena, via Fiorentina 1, Siena, Italy
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Xu X, Su J, Chen W, Wang C. Thermal stability and unfolding pathways of Sso7d and its mutant F31A: insight from molecular dynamics simulation. J Biomol Struct Dyn 2011; 28:717-27. [PMID: 21294584 DOI: 10.1080/07391102.2011.10508601] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The thermo-stability and unfolding behaviors of a small hyperthermophilic protein Sso7d as well as its single-point mutation F31A are studied by molecular dynamics simulation at temperatures of 300 K, 371 K and 500 K. Simulations at 300 K show that the F31A mutant displays a much larger flexibility than the wild type, which implies that the mutation obviously decreases the protein's stability. In the simulations at 371 K, although larger fluctuations were observed, both of these two maintain their stable conformations. High temperature simulations at 500 K suggest that the unfolding of these two proteins evolves along different pathways. For the wild-type protein, the C-terminal alpha-helix is melted at the early unfolding stage, whereas it is destroyed much later in the unfolding process of the F31A mutant. The results also show that the mutant unfolds much faster than its parent protein. The deeply buried aromatic cluster in the F31A mutant dissociates quickly relative to the wild-type protein at high temperature. Besides, it is found that the triple-stranded antiparallel β-sheet in the wild-type protein plays an important role in maintaining the stability of the entire structure.
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Affiliation(s)
- Xianjin Xu
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China
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Gera N, Hussain M, Wright RC, Rao BM. Highly stable binding proteins derived from the hyperthermophilic Sso7d scaffold. J Mol Biol 2011; 409:601-16. [PMID: 21515282 DOI: 10.1016/j.jmb.2011.04.020] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 04/08/2011] [Indexed: 12/16/2022]
Abstract
We have shown that highly stable binding proteins for a wide spectrum of targets can be generated through mutagenesis of the Sso7d protein from the hyperthermophilic archaeon Sulfolobus solfataricus. Sso7d is a small (~7 kDa, 63 amino acids) DNA-binding protein that lacks cysteine residues and has a melting temperature of nearly 100 °C. We generated a library of 10(8) Sso7d mutants by randomizing 10 amino acid residues on the DNA-binding surface of Sso7d, using yeast surface display. Binding proteins for a diverse set of model targets could be isolated from this library; our chosen targets included a small organic molecule (fluorescein), a 12 amino acid peptide fragment from the C-terminus of β-catenin, the model proteins hen egg lysozyme and streptavidin, and immunoglobulins from chicken and mouse. Without the application of any affinity maturation strategy, the binding proteins isolated had equilibrium dissociation constants in the nanomolar to micromolar range. Further, Sso7d-derived binding proteins could discriminate between closely related immunoglobulins. Mutant proteins based on Sso7d were expressed at high yields in the Escherichia coli cytoplasm. Despite extensive mutagenesis, Sso7d mutants have high thermal stability; five of six mutants analyzed have melting temperatures >89 °C. They are also resistant to chemical denaturation by guanidine hydrochloride and retain their secondary structure after extended incubation at extreme pH values. Because of their favorable properties, such as ease of recombinant expression, and high thermal, chemical and pH stability, Sso7d-derived binding proteins will have wide applicability in several areas of biotechnology and medicine.
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Affiliation(s)
- Nimish Gera
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
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Bernini A, Venditti V, Spiga O, Ciutti A, Prischi F, Consonni R, Zetta L, Arosio I, Fusi P, Guagliardi A, Niccolai N. NMR studies on the surface accessibility of the archaeal protein Sso7d by using TEMPOL and Gd(III)(DTPA-BMA) as paramagnetic probes. Biophys Chem 2008; 137:71-5. [DOI: 10.1016/j.bpc.2008.07.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Revised: 07/08/2008] [Accepted: 07/08/2008] [Indexed: 11/27/2022]
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