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Mutation in the CX3C Motif of G Protein Disrupts Its Interaction with Heparan Sulfate: A Calorimetric, Spectroscopic, and Molecular Docking Study. Int J Mol Sci 2022; 23:ijms23041950. [PMID: 35216066 PMCID: PMC8880246 DOI: 10.3390/ijms23041950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/22/2022] [Accepted: 01/28/2022] [Indexed: 11/16/2022] Open
Abstract
Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection in children and infants. To date, there is no effective vaccine available against RSV. Heparan sulfate is a type of glycosaminoglycan that aids in the attachment of the RSV to the host cell membrane via the G protein. In the present study, the effect of amino acid substitution on the structure and stability of the ectodomain G protein was studied. Further, it was investigated whether mutation (K117A) in the CX3C motif of G protein alters the binding with heparan sulfate. The point mutation significantly affects the conformational stability of the G protein. The mutant protein showed a low binding affinity with heparan sulfate as compared to the wild-type G protein, as determined by fluorescence quenching, isothermal titration calorimetry (ITC), and molecular docking studies. The low binding affinity and decreased stability suggested that this mutation may play an important role in prevention of attachment of virion to the host cell receptors. Collectively, this investigation suggests that mutation in the CX3C motif of G protein may likely improve the efficacy and safety of the RSV vaccine.
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Structural Characterization of Ectodomain G Protein of Respiratory Syncytial Virus and Its Interaction with Heparan Sulfate: Multi-Spectroscopic and In Silico Studies Elucidating Host-Pathogen Interactions. Molecules 2021; 26:molecules26237398. [PMID: 34885979 PMCID: PMC8658883 DOI: 10.3390/molecules26237398] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 02/03/2023] Open
Abstract
The global burden of disease caused by a respiratory syncytial virus (RSV) is becoming more widely recognized in young children and adults. Heparan sulfate helps in attaching the virion through G protein with the host cell membrane. In this study, we examined the structural changes of ectodomain G protein (edG) in a wide pH range. The absorbance results revealed that protein maintains its tertiary structure at physiological and highly acidic and alkaline pH. However, visible aggregation of protein was observed in mild acidic pH. The intrinsic fluorescence study shows no significant change in the λmax except at pH 12.0. The ANS fluorescence of edG at pH 2.0 and 3.0 forms an acid-induced molten globule-like state. The denaturation transition curve monitored by fluorescence spectroscopy revealed that urea and GdmCl induced denaturation native (N) ↔ denatured (D) state follows a two-state process. The fluorescence quenching, molecular docking, and 50 ns simulation measurements suggested that heparan sulfate showed excellent binding affinity to edG. Our binding study provides a preliminary insight into the interaction of edG to the host cell membrane via heparan sulfate. This binding can be inhibited using experimental approaches at the molecular level leading to the prevention of effective host–pathogen interaction.
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Hamza A, Shafat Z, Parray ZA, Hisamuddin M, Khan WH, Ahmed A, Almajhdi FN, Farrag MA, Mohammed AA, Islam A, Parveen S. Structural Characterization and Binding Studies of the Ectodomain G Protein of Respiratory Syncytial Virus Reveal the Crucial Role of pH with Possible Implications in Host-Pathogen Interactions. ACS OMEGA 2021; 6:10403-10414. [PMID: 34056193 PMCID: PMC8153753 DOI: 10.1021/acsomega.1c00800] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/25/2021] [Indexed: 06/12/2023]
Abstract
Respiratory syncytial virus (RSV) is a leading viral pathogen causing acute lower respiratory tract infection in children. The G protein of RSV is involved in attachment with the host cell. It is a neutralizing antigen and thus a vaccine candidate. Heparan sulfate is a type of glycosaminoglycan (GAG) present on the host cell membrane that is involved in attachment with the G protein of RSV. We describe a novel approach for efficient expression and purification of the ectodomain G protein in the prokaryotic system and its biophysical characterization. The native ectodomain G protein was purified using a two-step process by Ni-NTA and DEAE weak anion-exchange chromatography through the supernatant obtained after cell lysis. In addition, the denatured form of the protein was also purified from the solubilized inclusion bodies (IBs) by Ni-NTA affinity chromatography with a higher yield. Dynamic light scattering (DLS) was performed to confirm the homogeneity of the purified protein. The effect of pH on the stability and structure of the purified protein was studied by circular dichroism (CD), fluorescence, and absorbance spectroscopy techniques. Isothermal titration calorimetry (ITC) and microscale thermophoresis (MST) were exploited to demonstrate the interaction of heparan sulfate with the ectodomain G protein. The dynamic light scattering results showed that the purified protein was homogenic and had a well-folded native conformation. Biophysical characterization of the protein revealed that it was stable and had intact secondary and tertiary structures at pH 7.5. CD analysis revealed that the protein showed a loss in the secondary structure at pH values 5.5 and 3.5, while absorbance spectroscopy suggested a stable tertiary structure at pH values 7.5 and 5.5 with a probable aggregation pattern at pH 3.5. This loss in the structure of the ectodomain G protein at low pH can be correlated with its physiological activity. A slight change in pH might play a crucial role in host-pathogen interactions. The fluorescence intensity of the protein decreased on moving toward a lower pH with no spectral shift in emission maxima. In addition, isothermal titration calorimetry and microscale thermophoresis results showed strong binding affinity of the ectodomain G protein with heparan sulfate. The binding of heparan sulfate with protein was probably due to the electrostatic interaction of positively charged amino acid residues of the heparin-binding domain of the protein and the negatively charged group of GAGs. Future studies may involve the development of possible therapeutic agents interacting with the G protein and affecting the overall charge and pH that might hinder the host-pathogen interaction.
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Affiliation(s)
- Abu Hamza
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Zoya Shafat
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Zahoor Ahmad Parray
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Malik Hisamuddin
- Interdisciplinary
Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India
| | - Wajihul Hasan Khan
- Kusuma
School of Biological Sciences, Indian Institute
of Technology Delhi, New Delhi 110016, India
| | - Anwar Ahmed
- Centre
of Excellence in Biotechnology Research, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Fahad N. Almajhdi
- Department
of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
- Centre
of Excellence in Biotechnology Research, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mohamed A. Farrag
- Department
of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Arif Ahmed Mohammed
- Centre
of Excellence in Biotechnology Research, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Asimul Islam
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Shama Parveen
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India
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Shafat Z, Hamza A, Deeba F, Faizan MI, Khan N, Islam A, Ahmed A, Alamery SF, Parveen S. Optimization of parameters for expression and purification of G glycoprotein ectodomain of respiratory syncytial virus. Future Virol 2020. [DOI: 10.2217/fvl-2019-0157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aim: G glycoprotein ectodomain (Ge) of BA genotype of group B respiratory syncytial virus was expressed and purified to achieve maximum yield of the protein. Materials & methods: We optimized different parameters like strains, temperature, inducer concentration and post induction time period for efficient protein expression in Escherichia coli. The protein was purified using affinity chromatography and confirmed by western blotting. Results: It was concluded that a 5-h induction with 0.75 mM isopropyl β-D-1-thiogalactopyranoside at 37°C in BL21(DE3) cells was the most favorable condition for maximal protein expression. The far-UV circular dichroism spectroscopy suggested that it is an α-helical protein. Conclusion: The purified Ge protein can be characterized by antigenic and biophysical methods in future studies, which will probably assist in vaccine development.
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Affiliation(s)
- Zoya Shafat
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Abu Hamza
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Farah Deeba
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Md Imam Faizan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Nazim Khan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Asimul Islam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Anwar Ahmed
- Centre of Excellence in Biotechnology Research, College of Science, King Saud University, Riyadh, Saudi Arabia
- Protein Research Chair, Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Salman F Alamery
- Centre of Excellence in Biotechnology Research, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Shama Parveen
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
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Machado VB, Maróstica de Sá J, Miranda Prado AK, Alves de Toledo K, Regasini LO, Pereira de Souza F, Caruso ÍP, Fossey MA. Biophysical and flavonoid-binding studies of the G protein ectodomain of group A human respiratory syncytial virus. Heliyon 2019; 5:e01394. [PMID: 30976680 PMCID: PMC6439273 DOI: 10.1016/j.heliyon.2019.e01394] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/17/2019] [Accepted: 03/18/2019] [Indexed: 02/02/2023] Open
Abstract
The human Respiratory Syncytial Virus (hRSV) is the major causative agent of lower respiratory tract diseases in infants, young children and elderly. The membrane protein G is embedded in the viral lipid envelope and plays an adhesion function of the virus to host cells. The present study reports the production of the group A hRSV recombinant G protein ectodomain (edG) and its characterization of secondary structure and thermal unfolding by circular dichroism (CD), as well as the binding investigation of flavonoids quercetin and morin to this protein by fluorescent quenching. CD data reveal that edG is composed mostly of β-structure and its melting temperature is of 325 K. Fluorescence quenching experiments of hRSV edG show that the dissociation constants for the flavonoids binding are micromolar and the binding affinity for the edG/quercetin complex is inversely dependent on rising temperature while is directly dependent for the edG/morin interaction. The thermodynamic parameters suggest that hydrophobic contacts are important for the edG/morin association while van der Waals forces and hydrogen bonds contribute to the stabilization of the edG/quercetin complex. Thus, data reported herein may contribute to the development of new treatment strategies that prevent the viral infection by hRSV.
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Affiliation(s)
- Vitor Brassolatti Machado
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Department of Biology, São José do Rio Preto, SP, Brazil
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Multiuser Center for Biomolecular Innovation, Laboratory of Molecular Biology, São José do Rio Preto, SP, Brazil
| | - Jéssica Maróstica de Sá
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Multiuser Center for Biomolecular Innovation, Laboratory of Molecular Biology, São José do Rio Preto, SP, Brazil
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Department of Physics, São José do Rio Preto, SP, Brazil
| | - Ana Karla Miranda Prado
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Multiuser Center for Biomolecular Innovation, Laboratory of Molecular Biology, São José do Rio Preto, SP, Brazil
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Department of Physics, São José do Rio Preto, SP, Brazil
| | - Karina Alves de Toledo
- Faculdade de Ciências e Letras, UNESP, Department of Biology Sciences, Assis, SP, Brazil
| | - Luis Octávio Regasini
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Department of Chemistry and Environmental Sciences, São José do Rio Preto, SP, Brazil
| | - Fátima Pereira de Souza
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Multiuser Center for Biomolecular Innovation, Laboratory of Molecular Biology, São José do Rio Preto, SP, Brazil
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Department of Physics, São José do Rio Preto, SP, Brazil
| | - Ícaro Putinhon Caruso
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Multiuser Center for Biomolecular Innovation, Laboratory of Molecular Biology, São José do Rio Preto, SP, Brazil
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Department of Physics, São José do Rio Preto, SP, Brazil
- Corresponding author.
| | - Marcelo Andres Fossey
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Multiuser Center for Biomolecular Innovation, Laboratory of Molecular Biology, São José do Rio Preto, SP, Brazil
- Instituto de Biociências, Letras e Ciências Exatas, UNESP, Department of Physics, São José do Rio Preto, SP, Brazil
- Corresponding author.
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