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Diaz A, Ramakrishnan V. Effect of osmolytes on the EcoRI endonuclease: Insights into hydration and protein dynamics from molecular dynamics simulations. Comput Biol Chem 2023; 105:107883. [PMID: 37210944 DOI: 10.1016/j.compbiolchem.2023.107883] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 05/16/2023] [Accepted: 05/16/2023] [Indexed: 05/23/2023]
Abstract
Osmolytes play an important role in cellular physiology by modulating the properties of proteins, including their molecular specificity. EcoRI is a model restriction enzyme whose specificity to DNA is altered in the presence of osmolytes. Here, we investigate the effect of two different osmolytes, glycerol and DMSO, on the dynamics and hydration of the EcoRI enzyme using molecular dynamics simulations. Our results show that the osmolytes, alter the essential dynamics of EcoRI. Particularly, we observe that the dynamics of the arm region of EcoRI which is involved in DNA binding is significantly altered. In addition, conformational free energy analyses reveals that the osmolytes bring about a change in the landscape similar to that of EcoRI bound to cognate DNA. We further observe that the hydration of the enzyme for each of the osmolyte is different, indicating that the mechanism of action of each of these osmolytes could be different. Further analyses of interfacial water dynamics using rotational autocorrelation function reveals that while the protein surface contributes to a slower tumbling motion of water, osmolytes, additionally contribute to the slowing of the angular motion of the water molecules. Entropy analysis also corroborates with this finding. We also find that the slowed rotational motion of interfacial waters in the presence of osmolytes contributes to a slowed relaxation of the hydrogen bonds between the interfacial waters and the functionally important residues in the protein. Taken together, our results show that osmolytes alter the dynamics of the protein by altering the dynamics of water. This altered dynamics, mediated by the changes in the water dynamics and hydrogen bonds with functionally important residues, may contribute to the altered specificity of EcoRI in the presence of osmolytes.
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Affiliation(s)
- Aathithya Diaz
- Computational Molecular Biophysics Laboratory, Bioinformatics Center, School of Chemical & Biotechnology, SASTRA Deemed to be University, Thanjavur 613401, Tamil Nadu, India
| | - Vigneshwar Ramakrishnan
- Computational Molecular Biophysics Laboratory, Bioinformatics Center, School of Chemical & Biotechnology, SASTRA Deemed to be University, Thanjavur 613401, Tamil Nadu, India.
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Venkatachalam S, Murlidharan N, Krishnan SR, Ramakrishnan C, Setshedi M, Pandian R, Barh D, Tiwari S, Azevedo V, Sayed Y, Gromiha MM. Understanding Drug Resistance of Wild-Type and L38HL Insertion Mutant of HIV-1 C Protease to Saquinavir. Genes (Basel) 2023; 14:533. [PMID: 36833460 PMCID: PMC9957153 DOI: 10.3390/genes14020533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 02/25/2023] Open
Abstract
Acquired immunodeficiency syndrome (AIDS) is one of the most challenging infectious diseases to treat on a global scale. Understanding the mechanisms underlying the development of drug resistance is necessary for novel therapeutics. HIV subtype C is known to harbor mutations at critical positions of HIV aspartic protease compared to HIV subtype B, which affects the binding affinity. Recently, a novel double-insertion mutation at codon 38 (L38HL) was characterized in HIV subtype C protease, whose effects on the interaction with protease inhibitors are hitherto unknown. In this study, the potential of L38HL double-insertion in HIV subtype C protease to induce a drug resistance phenotype towards the protease inhibitor, Saquinavir (SQV), was probed using various computational techniques, such as molecular dynamics simulations, binding free energy calculations, local conformational changes and principal component analysis. The results indicate that the L38HL mutation exhibits an increase in flexibility at the hinge and flap regions with a decrease in the binding affinity of SQV in comparison with wild-type HIV protease C. Further, we observed a wide opening at the binding site in the L38HL variant due to an alteration in flap dynamics, leading to a decrease in interactions with the binding site of the mutant protease. It is supported by an altered direction of motion of flap residues in the L38HL variant compared with the wild-type. These results provide deep insights into understanding the potential drug resistance phenotype in infected individuals.
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Affiliation(s)
- Sankaran Venkatachalam
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Nisha Murlidharan
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sowmya R. Krishnan
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - C. Ramakrishnan
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Mpho Setshedi
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2000, South Africa
| | - Ramesh Pandian
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2000, South Africa
| | - Debmalya Barh
- Department of Genetics, Ecology, and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Belo Horizonte 31270-901, Brazil
- Institute of Integrative Omics and Applied Biotechnology (IIOAB), Nonakuri, Purba Medinipur 721172, West Bengal, India
| | - Sandeep Tiwari
- Department of Genetics, Ecology, and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Belo Horizonte 31270-901, Brazil
- Institute of Biology, Federal University of Bahia, Salvador, BA 40110-909, Brazil
- Institute of Health Sciences, Federal University of Bahia, Salvador, BA 40110-909, Brazil
| | - Vasco Azevedo
- Department of Genetics, Ecology, and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Belo Horizonte 31270-901, Brazil
| | - Yasien Sayed
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2000, South Africa
| | - M. Michael Gromiha
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
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Zhao G, Hu T, Li J, Wei H, Shang H, Guan Y. A RCA-based assay for analyzing individual strand break in DNA heteroduplex cleavage by restriction endonucleases. Chem Commun (Camb) 2015; 50:11930-3. [PMID: 25157639 DOI: 10.1039/c4cc05314a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We have developed a rapid and high-throughput assay based on rolling circle amplification, to distinguish individual strand cleavage of DNA duplexes by restriction endonucleases. As an illustration, we analyzed nicking activity of Nb.BbvCI and uneven cleavage of LNA modified DNA by EcoRI. This assay has potential for analyzing protein-DNA interactions.
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Affiliation(s)
- Guojie Zhao
- Key Laboratory of Medical Cell Biology (Ministry of Education), Department of Biochemistry and Molecular Biology, China Medical University, Shenyang, Liaoning 110001, China.
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