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Banerjee R, Sheet T, Banerjee S, Biondi B, Formaggio F, Toniolo C, Peggion C. C α-Methyl-l-valine: A Preferential Choice over α-Aminoisobutyric Acid for Designing Right-Handed α-Helical Scaffolds. Biochemistry 2021; 60:2704-2714. [PMID: 34463474 DOI: 10.1021/acs.biochem.1c00340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In synthetic peptides containing Gly and coded α-amino acids, one of the most common practices to enhance their helical extent is to incorporate a large number of l-Ala residues along with noncoded, strongly foldameric α-aminoisobutyric acid (Aib) units. Earlier studies have established that Aib-based peptides, with propensity for both the 310- and α-helices, have a tendency to form ordered three-dimensional structure that is much stronger than that exhibited by their l-Ala rich counterparts. However, the achiral nature of Aib induces an inherent, equal preference for the right- and left-handed helical conformations as found in Aib homopeptide stretches. This property poses challenges in the analysis of a model peptide helical conformation based on chirospectroscopic techniques like electronic circular dichroism (ECD), a very important tool for assigning secondary structures. To overcome such ambiguity, we have synthesized and investigated a thermally stable 14-mer peptide in which each of the Aib residues of our previously designed and reported analogue ABGY (where B stands for Aib) is replaced by Cα-methyl-l-valine (L-AMV). Analysis of the results described here from complementary ECD and 1H nuclear magnetic resonance spectroscopic techniques in a variety of environments firmly establishes that the L-AMV-containing peptide exhibits a significantly stronger preference compared to that of its Aib parent in terms of conferring α-helical character. Furthermore, being a chiral α-amino acid, L-AMV shows an intrinsic, extremely strong bias for a quite specific (right-handed) screw sense. These findings emphasize the relevance of L-AMV as a more appropriate unit for the design of right-handed α-helical peptide models that may be utilized as conformationally constrained scaffolds.
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Affiliation(s)
| | | | | | - Barbara Biondi
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Fernando Formaggio
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Claudio Toniolo
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Cristina Peggion
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
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Pimenta J, Sardinha J, Marques CC, Domingos A, Baptista MC, Barbas JP, Martins IC, Mesquita P, Pessa P, Soares R, Viegas A, Cabrita E, Horta EMA, Fontes CA, Prates AMJ, Pereira MLNR. Inhibition of ovine in vitro fertilization by anti-Prt antibody: hypothetical model for Prt/ZP interaction. Reprod Biol Endocrinol 2013; 11:25. [PMID: 23531155 PMCID: PMC3617107 DOI: 10.1186/1477-7827-11-25] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 03/18/2013] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The impact of prion proteins in the rules that dictate biological reproduction is still poorly understood. Likewise, the role of prnt gene, encoding the prion-like protein testis specific (Prt), in ram reproductive physiology remains largely unknown. In this study, we assessed the effect of Prt in ovine fertilization by using an anti-Prt antibody (APPA) in fertilization medium incubated with spermatozoa and oocytes. Moreover, a computational model was constructed to infer how the results obtained could be related to a hypothetical role for Prt in sperm-zona pellucida (ZP) binding. METHODS Mature ovine oocytes were transferred to fertilization medium alone (control) or supplemented with APPA, or pre-immune serum (CSerum). Oocytes were inseminated with ovine spermatozoa and after 18 h, presumptive zygotes (n=142) were fixed to evaluate fertilization rates or transferred (n=374) for embryo culture until D6-7. Predicted ovine Prt tertiary structure was compared with data obtained by circular dichroism spectroscopy (CD) and a protein-protein computational docking model was estimated for a hypothetical Prt/ZP interaction. RESULTS The fertilizing rate was lower (P=0.006) in APPA group (46.0+/-6.79%) when compared to control (78.5+/-7.47%) and CSerum (64.5+/-6.65%) groups. In addition, the cleavage rate was higher (P<0.0001) in control (44.1+/-4.15%) than in APPA group (19.7+/-4.22%). Prt CD spectroscopy showed a 22% alpha-helical structure in 30% (m/v) aqueous trifluoroethanol (TFE) and 17% alpha in 0.6% (m/v) TFE. The predominant alpha-helical secondary structure detected correlates with the predicted three dimensional structure for ovine Prt, which was subsequently used to test Prt/ZP docking. Computational analyses predicted a favorable Prt-binding activity towards ZP domains. CONCLUSIONS Our data indicates that the presence of APPA reduces the number of fertilized oocytes and of cleaved embryos. Moreover, the CD analysis data reinforces the predicted ovine Prt trend towards an alpha-helical structure. Predicted protein-protein docking suggests a possible interaction between Prt and ZP, thus supporting an important role for Prt in ovine fertilization.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacology
- Circular Dichroism
- Egg Proteins/chemistry
- Egg Proteins/genetics
- Egg Proteins/metabolism
- Embryo, Mammalian/drug effects
- Embryo, Mammalian/embryology
- Embryo, Mammalian/metabolism
- Female
- Fertilization in Vitro/drug effects
- Male
- Membrane Glycoproteins/chemistry
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Models, Molecular
- Molecular Sequence Data
- Prions/chemistry
- Prions/immunology
- Prions/metabolism
- Protein Binding
- Protein Conformation/drug effects
- Protein Structure, Secondary/drug effects
- Protein Structure, Tertiary
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Sequence Homology, Amino Acid
- Sheep
- Sperm-Ovum Interactions/drug effects
- Time Factors
- Trifluoroethanol/chemistry
- Trifluoroethanol/pharmacology
- Zona Pellucida/metabolism
- Zona Pellucida Glycoproteins
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Affiliation(s)
- Jorge Pimenta
- Unidade de Biotecnologia e Recursos Genéticos, Instituto Nacional de Investigação Agrária e Veterinária Santarém, Quinta da Fonte Boa, Vale de Santarém, 2005-048, Portugal
- CIISA, Faculdade de Medicina Veterinária (FMV), Universidade Técnica de Lisboa, Lisbon, Portugal
| | - João Sardinha
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Carla C Marques
- Unidade de Biotecnologia e Recursos Genéticos, Instituto Nacional de Investigação Agrária e Veterinária Santarém, Quinta da Fonte Boa, Vale de Santarém, 2005-048, Portugal
| | - Ana Domingos
- IHMT-CMDT – Instituto de Higiene e Medicina Tropical, Centro de Malária e Doenças Tropicais, Lisbon, Portugal
| | - Maria C Baptista
- Unidade de Biotecnologia e Recursos Genéticos, Instituto Nacional de Investigação Agrária e Veterinária Santarém, Quinta da Fonte Boa, Vale de Santarém, 2005-048, Portugal
| | - João P Barbas
- Unidade de Biotecnologia e Recursos Genéticos, Instituto Nacional de Investigação Agrária e Veterinária Santarém, Quinta da Fonte Boa, Vale de Santarém, 2005-048, Portugal
| | - Ivo C Martins
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof. Egas Moniz, Lisbon, 1649-028, Portugal
| | - Patrícia Mesquita
- Unidade de Biotecnologia e Recursos Genéticos, Instituto Nacional de Investigação Agrária e Veterinária Santarém, Quinta da Fonte Boa, Vale de Santarém, 2005-048, Portugal
| | - Pedro Pessa
- Hospital Universitário de Coimbra, Coimbra, Portugal
| | - Rui Soares
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Aldino Viegas
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Eurico Cabrita
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - EM António Horta
- Unidade de Biotecnologia e Recursos Genéticos, Instituto Nacional de Investigação Agrária e Veterinária Santarém, Quinta da Fonte Boa, Vale de Santarém, 2005-048, Portugal
| | - Carlos A Fontes
- CIISA, Faculdade de Medicina Veterinária (FMV), Universidade Técnica de Lisboa, Lisbon, Portugal
| | - AM José Prates
- CIISA, Faculdade de Medicina Veterinária (FMV), Universidade Técnica de Lisboa, Lisbon, Portugal
| | - MLN Rosa Pereira
- Unidade de Biotecnologia e Recursos Genéticos, Instituto Nacional de Investigação Agrária e Veterinária Santarém, Quinta da Fonte Boa, Vale de Santarém, 2005-048, Portugal
- Escola Universitária Vasco da Gama, Coimbra, Portugal
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Katragadda M, Alderfer JL, Yeagle PL. Assembly of a polytopic membrane protein structure from the solution structures of overlapping peptide fragments of bacteriorhodopsin. Biophys J 2001; 81:1029-36. [PMID: 11463644 PMCID: PMC1301572 DOI: 10.1016/s0006-3495(01)75760-8] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Three-dimensional structures of only a handful of membrane proteins have been solved, in contrast to the thousands of structures of water-soluble proteins. Difficulties in crystallization have inhibited the determination of the three-dimensional structure of membrane proteins by x-ray crystallography and have spotlighted the critical need for alternative approaches to membrane protein structure. A new approach to the three-dimensional structure of membrane proteins has been developed and tested on the integral membrane protein, bacteriorhodopsin, the crystal structure of which had previously been determined. An overlapping series of 13 peptides, spanning the entire sequence of bacteriorhodopsin, was synthesized, and the structures of these peptides were determined by NMR in dimethylsulfoxide solution. These structures were assembled into a three-dimensional construct by superimposing the overlapping sequences at the ends of each peptide. Onto this construct were written all the distance and angle constraints obtained from the individual solution structures along with a limited number of experimental inter-helical distance constraints, and the construct was subjected to simulated annealing. A three-dimensional structure, determined exclusively by the experimental constraints, emerged that was similar to the crystal structure of this protein. This result suggests an alternative approach to the acquisition of structural information for membrane proteins consisting of helical bundles.
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Affiliation(s)
- M Katragadda
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269, USA
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Katragadda M, Chopra A, Bennett M, Alderfer JL, Yeagle PL, Albert AD. Structures of the transmembrane helices of the G-protein coupled receptor, rhodopsin. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2001; 58:79-89. [PMID: 11454172 DOI: 10.1034/j.1399-3011.2001.00904.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An hypothesis is tested that individual peptides corresponding to the transmembrane helices of the membrane protein, rhodopsin, would form helices in solution similar to those in the native protein. Peptides containing the sequences of helices 1, 4 and 5 of rhodopsin were synthesized. Two peptides, with overlapping sequences at their termini, were synthesized to cover each of the helices. The peptides from helix 1 and helix 4 were helical throughout most of their length. The N- and C-termini of all the peptides were disordered and proline caused opening of the helical structure in both helix 1 and helix 4. The peptides from helix 5 were helical in the middle segment of each peptide, with larger disordered regions in the N- and C-termini than for helices 1 and 4. These observations show that there is a strong helical propensity in the amino acid sequences corresponding to the transmembrane domain of this G-protein coupled receptor. In the case of the peptides from helix 4, it was possible to superimpose the structures of the overlapping sequences to produce a construct covering the whole of the sequence of helix 4 of rhodopsin. As similar superposition for the peptides from helix 1 also produced a construct, but somewhat less successfully because of the disordering in the region of sequence overlap. This latter problem was more severe for helix 5 and therefore a single peptide was synthesized for the entire sequence of this helix, and its structure determined. It proved to be helical throughout. Comparison of all these structures with the recent crystal structure of rhodopsin revealed that the peptide structures mimicked the structures seen in the whole protein. Thus similar studies of peptides may provide useful information on the secondary structure of other transmembrane proteins built around helical bundles.
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Affiliation(s)
- M Katragadda
- Department of Biophysics, Roswell Park Cancer Institute, Buffalo, USA
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