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Sun Y, Ko DH, Gao J, Fu K, Gao Y, Zhang Q, Baldi S, Hong T, Ivanov I, He Y, Tian H. Unraveling the salt tolerance of Phi29 DNA polymerase using compartmentalized self-replication and microfluidics platform. Front Microbiol 2023; 14:1267196. [PMID: 38029082 PMCID: PMC10661337 DOI: 10.3389/fmicb.2023.1267196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/24/2023] [Indexed: 12/01/2023] Open
Abstract
In Phi29-α-hemolysin (α-HL) nanopore sequencing systems, a strong electrochemical signal is dependent on a high concentration of salt. However, high salt concentrations adversely affect polymerase activity. Sequencing by synthesis (SBS) requires the use of phi29 polymerase without exonuclease activity to prevent the degradation of modified nucleotide tags; however, the lack of exonuclease activity also affects polymerase processivity. This study aimed to optimize phi29 polymerase for improved salt tolerance and processivity while maintaining its lack of exonuclease activity to meet the requirements of nanopore sequencing. Using salt tolerance compartmentalized self-replication (stCSR) and a microfluidic platform, we obtained 11 mutant sites with enhanced salt tolerance attributes. Sequencing and biochemical analyses revealed that the substitution of conserved amino acids such as G197D, Y369E, T372N, and I378R plays a critical role in maintaining the processivity of exonuclease-deficient phi29 polymerase under high salt conditions. Furthermore, Y369E and T372N have been identified as important determinants of DNA polymerase binding affinity. This study provides insights into optimizing polymerase processability under high-salt conditions for real-time polymerase nanopore sequencing, paving the way for improved performance and applications in nanopore sequencing technologies.
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Affiliation(s)
- Yaping Sun
- Research Center of Molecular Diagnostics and Sequencing, Research Institute of Tsinghua University in Shenzhen, Shenzhen, China
| | - Danny Hsu Ko
- Research Center of Molecular Diagnostics and Sequencing, Axbio Biotechnology (Shenzhen) Co., Ltd., Shenzhen, China
| | - Jie Gao
- Research Center of Molecular Diagnostics and Sequencing, Axbio Biotechnology (Shenzhen) Co., Ltd., Shenzhen, China
| | - Kang Fu
- Research Center of Molecular Diagnostics and Sequencing, Axbio Biotechnology (Shenzhen) Co., Ltd., Shenzhen, China
| | - Yaping Gao
- Research Center of Molecular Diagnostics and Sequencing, Research Institute of Tsinghua University in Shenzhen, Shenzhen, China
| | - Qiwen Zhang
- Research Center of Molecular Diagnostics and Sequencing, Axbio Biotechnology (Shenzhen) Co., Ltd., Shenzhen, China
| | - Salem Baldi
- Research Center of Molecular Diagnostics and Sequencing, Axbio Biotechnology (Shenzhen) Co., Ltd., Shenzhen, China
| | - Tao Hong
- Research Center of Molecular Diagnostics and Sequencing, Axbio Biotechnology (Shenzhen) Co., Ltd., Shenzhen, China
| | - Igor Ivanov
- Research Center of Molecular Diagnostics and Sequencing, Axbio Biotechnology (Shenzhen) Co., Ltd., Shenzhen, China
| | - Yun He
- Research Center of Molecular Diagnostics and Sequencing, Research Institute of Tsinghua University in Shenzhen, Shenzhen, China
| | - Hui Tian
- Research Center of Molecular Diagnostics and Sequencing, Axbio Biotechnology (Shenzhen) Co., Ltd., Shenzhen, China
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Dahl JM, Thomas N, Tracy MA, Hearn BL, Perera L, Kennedy SR, Herr AJ, Kunkel TA. Probing the mechanisms of two exonuclease domain mutators of DNA polymerase ϵ. Nucleic Acids Res 2022; 50:962-974. [PMID: 35037018 DOI: 10.1093/nar/gkab1255] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 11/21/2021] [Accepted: 12/08/2021] [Indexed: 11/15/2022] Open
Abstract
We report the properties of two mutations in the exonuclease domain of the Saccharomyces cerevisiae DNA polymerase ϵ. One, pol2-Y473F, increases the mutation rate by about 20-fold, similar to the catalytically dead pol2-D290A/E290A mutant. The other, pol2-N378K, is a stronger mutator. Both retain the ability to excise a nucleotide from double-stranded DNA, but with impaired activity. pol2-Y473F degrades DNA poorly, while pol2-N378K degrades single-stranded DNA at an elevated rate relative to double-stranded DNA. These data suggest that pol2-Y473F reduces the capacity of the enzyme to perform catalysis in the exonuclease active site, while pol2-N378K impairs partitioning to the exonuclease active site. Relative to wild-type Pol ϵ, both variants decrease the dNTP concentration required to elicit a switch between proofreading and polymerization by more than an order of magnitude. While neither mutation appears to alter the sequence specificity of polymerization, the N378K mutation stimulates polymerase activity, increasing the probability of incorporation and extension of a mismatch. Considered together, these data indicate that impairing the primer strand transfer pathway required for proofreading increases the probability of common mutations by Pol ϵ, elucidating the association of homologous mutations in human DNA polymerase ϵ with cancer.
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Affiliation(s)
- Joseph M Dahl
- Genome Integrity Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - Natalie Thomas
- Genome Integrity Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - Maxwell A Tracy
- Department of Laboratory Medicine and Pathology, UW Medicine, Seattle, WA 98195, USA
| | - Brady L Hearn
- Department of Laboratory Medicine and Pathology, UW Medicine, Seattle, WA 98195, USA
| | - Lalith Perera
- Genome Integrity Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - Scott R Kennedy
- Department of Laboratory Medicine and Pathology, UW Medicine, Seattle, WA 98195, USA
| | - Alan J Herr
- Department of Laboratory Medicine and Pathology, UW Medicine, Seattle, WA 98195, USA
| | - Thomas A Kunkel
- Genome Integrity Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
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Long C, Romero ME, La Rocco D, Yu J. Dissecting nucleotide selectivity in viral RNA polymerases. Comput Struct Biotechnol J 2021; 19:3339-3348. [PMID: 34104356 PMCID: PMC8175102 DOI: 10.1016/j.csbj.2021.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 01/18/2023] Open
Abstract
Designing antiviral therapeutics is of great concern per current pandemics caused by novel coronavirus or SARS-CoV-2. The core polymerase enzyme in the viral replication/transcription machinery is generally conserved and serves well for drug target. In this work we briefly review structural biology and computational clues on representative single-subunit viral polymerases that are more or less connected with SARS-CoV-2 RNA dependent RNA polymerase (RdRp), in particular, to elucidate how nucleotide substrates and potential drug analogs are selected in the viral genome synthesis. To do that, we first survey two well studied RdRps from Polio virus and hepatitis C virus in regard to structural motifs and key residues that have been identified for the nucleotide selectivity. Then we focus on related structural and biochemical characteristics discovered for the SARS-CoV-2 RdRp. To further compare, we summarize what we have learned computationally from phage T7 RNA polymerase (RNAP) on its stepwise nucleotide selectivity, and extend discussion to a structurally similar human mitochondria RNAP, which deserves special attention as it cannot be adversely affected by antiviral treatments. We also include viral phi29 DNA polymerase for comparison, which has both helicase and proofreading activities on top of nucleotide selectivity for replication fidelity control. The helicase and proofreading functions are achieved by protein components in addition to RdRp in the coronavirus replication-transcription machine, with the proofreading strategy important for the fidelity control in synthesizing a comparatively large viral genome.
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Affiliation(s)
- Chunhong Long
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
| | | | - Daniel La Rocco
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - Jin Yu
- Department of Physics and Astronomy, Department of Chemistry, NSF-Simons Center for Multiscale Cell Fate Research, University of California, Irvine, CA 92697, USA
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Long N, Qiao Y, Xu Z, Tu J, Lu Z. Recent advances and application in whole-genome multiple displacement amplification. QUANTITATIVE BIOLOGY 2020. [DOI: 10.1007/s40484-020-0217-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Pollock K, Liu M, Zaleska M, Meniconi M, Pfuhl M, Collins I, Guettler S. Fragment-based screening identifies molecules targeting the substrate-binding ankyrin repeat domains of tankyrase. Sci Rep 2019; 9:19130. [PMID: 31836723 PMCID: PMC6911004 DOI: 10.1038/s41598-019-55240-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 11/22/2019] [Indexed: 12/16/2022] Open
Abstract
The PARP enzyme and scaffolding protein tankyrase (TNKS, TNKS2) uses its ankyrin repeat clusters (ARCs) to bind a wide range of proteins and thereby controls diverse cellular functions. A number of these are implicated in cancer-relevant processes, including Wnt/β-catenin signalling, Hippo signalling and telomere maintenance. The ARCs recognise a conserved tankyrase-binding peptide motif (TBM). All currently available tankyrase inhibitors target the catalytic domain and inhibit tankyrase's poly(ADP-ribosyl)ation function. However, there is emerging evidence that catalysis-independent "scaffolding" mechanisms contribute to tankyrase function. Here we report a fragment-based screening programme against tankyrase ARC domains, using a combination of biophysical assays, including differential scanning fluorimetry (DSF) and nuclear magnetic resonance (NMR) spectroscopy. We identify fragment molecules that will serve as starting points for the development of tankyrase substrate binding antagonists. Such compounds will enable probing the scaffolding functions of tankyrase, and may, in the future, provide potential alternative therapeutic approaches to inhibiting tankyrase activity in cancer and other conditions.
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Affiliation(s)
- Katie Pollock
- Divisions of Structural Biology & Cancer Biology, The Institute of Cancer Research (ICR), London, SW7 3RP, United Kingdom
- Division of Cancer Therapeutics, The Institute of Cancer Research (ICR), London, SW7 3RP, United Kingdom
- Cancer Research UK Beatson Institute, Drug Discovery Programme, Glasgow, G61 1BD, United Kingdom
| | - Manjuan Liu
- Division of Cancer Therapeutics, The Institute of Cancer Research (ICR), London, SW7 3RP, United Kingdom
| | - Mariola Zaleska
- Divisions of Structural Biology & Cancer Biology, The Institute of Cancer Research (ICR), London, SW7 3RP, United Kingdom
| | - Mirco Meniconi
- Division of Cancer Therapeutics, The Institute of Cancer Research (ICR), London, SW7 3RP, United Kingdom
| | - Mark Pfuhl
- School of Cardiovascular Medicine and Sciences and Randall Centre, King's College London, Guy's Campus, London, SE1 1UL, United Kingdom
| | - Ian Collins
- Division of Cancer Therapeutics, The Institute of Cancer Research (ICR), London, SW7 3RP, United Kingdom.
| | - Sebastian Guettler
- Divisions of Structural Biology & Cancer Biology, The Institute of Cancer Research (ICR), London, SW7 3RP, United Kingdom.
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