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Mótyán JA, Tőzsér J. The human retroviral-like aspartic protease 1 (ASPRV1): From in vitro studies to clinical correlations. J Biol Chem 2024; 300:107634. [PMID: 39098535 PMCID: PMC11402058 DOI: 10.1016/j.jbc.2024.107634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 07/25/2024] [Accepted: 07/27/2024] [Indexed: 08/06/2024] Open
Abstract
The human retroviral-like aspartic protease 1 (ASPRV1) is a retroviral-like protein that was first identified in the skin due to its expression in the stratum granulosum layer of the epidermis. Accordingly, it is also referred to as skin-specific aspartic protease. Similar to the retroviral polyproteins, the full-length ASPRV1 also undergoes self-proteolysis, the processing of the precursor is necessary for the autoactivation of the protease domain. ASPRV1's functions are well-established at the level of the skin: it is part of the epidermal proteolytic network and has a significant contribution to skin moisturization via the limited proteolysis of filaggrin; it is only natural protein substrate identified so far. Filaggrin and ASPRV1 are also specific for mammalians, these proteins provide unique features for the skins of these species, and the importance of filaggrin processing in hydration is proved by the fact that some ASPRV1 mutations are associated with skin diseases such as ichthyosis. ASPRV1 was also found to be expressed in macrophage-like neutrophil cells, indicating that its functions are not limited to the skin. In addition, differential expression of ASPRV1 was detected in many diseases, with yet unknown significance. The currently known enzymatic characteristics-that had been revealed mainly by in vitro studies-and correlations with pathogenic phenotypes imply potentially important functions in multiple cell types, which makes the protein a promising target of functional studies. In this review we describe the currently available knowledge and future perspective in regard to ASPRV1.
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Affiliation(s)
- János András Mótyán
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
| | - József Tőzsér
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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Development of a Bio-Layer Interferometry-Based Protease Assay Using HIV-1 Protease as a Model. Viruses 2021; 13:v13061183. [PMID: 34205716 PMCID: PMC8235736 DOI: 10.3390/v13061183] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/09/2021] [Accepted: 06/19/2021] [Indexed: 11/16/2022] Open
Abstract
Proteolytic enzymes have great significance in medicine and the pharmaceutical industry and are applied in multiple fields of life sciences. Therefore, cost-efficient, reliable and sensitive real-time monitoring methods are highly desirable to measure protease activity. In this paper, we describe the development of a new experimental approach for investigation of proteolytic enzymes. The method was designed by the combination of recombinant fusion protein substrates and bio-layer interferometry (BLI). The protease (PR) of human immunodeficiency virus type 1 (HIV-1) was applied as model enzyme to set up and test the method. The principle of the assay is that the recombinant protein substrates immobilized to the surface of biosensor are specifically cleaved by the PR, and the substrate processing can be followed by measuring change in the layer thickness by optical measurement. We successfully used this method to detect the HIV-1 PR activity in real time, and the initial rate of the signal decrease was found to be proportional to the enzyme activity. Substrates representing wild-type and modified cleavage sites were designed to study HIV-1 PR's specificity, and the BLI-based measurements showed differential cleavage efficiency of the substrates, which was proven by enzyme kinetic measurements. We applied this BLI-based assay to experimentally confirm the existence of extended binding sites at the surface of HIV-1 PR. We found the measurements may be performed using lysates of cells expressing the fusion protein, without primary purification of the substrate. The designed BLI-based protease assay is high-throughput-compatible and enables real-time and small-volume measurements, thus providing a new and versatile approach to study proteolytic enzymes.
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Specificity of the HIV-1 Protease on Substrates Representing the Cleavage Site in the Proximal Zinc-Finger of HIV-1 Nucleocapsid Protein. Viruses 2021; 13:v13061092. [PMID: 34201134 PMCID: PMC8227227 DOI: 10.3390/v13061092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/02/2021] [Accepted: 06/03/2021] [Indexed: 12/14/2022] Open
Abstract
To explore the sequence context-dependent nature of the human immunodeficiency virus type 1 (HIV-1) protease’s specificity and to provide a rationale for viral mutagenesis to study the potential role of the nucleocapsid (NC) processing in HIV-1 replication, synthetic oligopeptide substrates representing the wild-type and modified versions of the proximal cleavage site of HIV-1 NC were assayed as substrates of the HIV-1 protease (PR). The S1′ substrate binding site of HIV-1 PR was studied by an in vitro assay using KIVKCF↓NCGK decapeptides having amino acid substitutions of N17 residue of the cleavage site of the first zinc-finger domain, and in silico calculations were also performed to investigate amino acid preferences of S1′ site. Second site substitutions have also been designed to produce “revertant” substrates and convert a non-hydrolysable sequence (having glycine in place of N17) to a substrate. The specificity constants obtained for peptides containing non-charged P1′ substitutions correlated well with the residue volume, while the correlation with the calculated interaction energies showed the importance of hydrophobicity: interaction energies with polar residues were related to substantially lower specificity constants. Cleavable “revertants” showed one residue shift of cleavage position due to an alternative productive binding mode, and surprisingly, a double cleavage of a substrate was also observed. The results revealed the importance of alternative binding possibilities of substrates into the HIV-1 PR. The introduction of the “revertant” mutations into infectious virus clones may provide further insights into the potential role of NC processing in the early phase of the viral life-cycle.
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Kassay N, Mótyán JA, Matúz K, Golda M, Tőzsér J. Biochemical Characterization, Specificity and Inhibition Studies of HTLV-1, HTLV-2, and HTLV-3 Proteases. Life (Basel) 2021; 11:life11020127. [PMID: 33562087 PMCID: PMC7915765 DOI: 10.3390/life11020127] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 01/03/2023] Open
Abstract
The human T-lymphotropic viruses (HTLVs) are causative agents of severe diseases including adult T-cell leukemia. Similar to human immunodeficiency viruses (HIVs), the viral protease (PR) plays a crucial role in the viral life-cycle via the processing of the viral polyproteins. Thus, it is a potential target of anti-retroviral therapies. In this study, we performed in vitro comparative analysis of human T-cell leukemia virus type 1, 2, and 3 (HTLV-1, -2, and -3) proteases. Amino acid preferences of S4 to S1′ subsites were studied by using a series of synthetic oligopeptide substrates representing the natural and modified cleavage site sequences of the proteases. Biochemical characteristics of the different PRs were also determined, including catalytic efficiencies and dependence of activity on pH, temperature, and ionic strength. We investigated the effects of different HIV-1 PR inhibitors (atazanavir, darunavir, DMP-323, indinavir, ritonavir, and saquinavir) on enzyme activities, and inhibitory potentials of IB-268 and IB-269 inhibitors that were previously designed against HTLV-1 PR. Comparative biochemical analysis of HTLV-1, -2, and -3 PRs may help understand the characteristic similarities and differences between these enzymes in order to estimate the potential of the appearance of drug-resistance against specific HTLV-1 PR inhibitors.
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Affiliation(s)
- Norbert Kassay
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (N.K.); (K.M.); (M.G.)
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - János András Mótyán
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (N.K.); (K.M.); (M.G.)
- Correspondence: (J.A.M.); (J.T.); Tel.: +36-52-512-900 (J.A.M. & J.T.)
| | - Krisztina Matúz
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (N.K.); (K.M.); (M.G.)
| | - Mária Golda
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (N.K.); (K.M.); (M.G.)
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - József Tőzsér
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (N.K.); (K.M.); (M.G.)
- Correspondence: (J.A.M.); (J.T.); Tel.: +36-52-512-900 (J.A.M. & J.T.)
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Identification of Host Cellular Protein Substrates of SARS-COV-2 Main Protease. Int J Mol Sci 2020; 21:ijms21249523. [PMID: 33333742 PMCID: PMC7765187 DOI: 10.3390/ijms21249523] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/11/2020] [Accepted: 12/12/2020] [Indexed: 12/20/2022] Open
Abstract
The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease-19 (COVID-19) being associated with severe pneumonia. Like with other viruses, the interaction of SARS-CoV-2 with host cell proteins is necessary for successful replication, and cleavage of cellular targets by the viral protease also may contribute to the pathogenesis, but knowledge about the human proteins that are processed by the main protease (3CLpro) of SARS-CoV-2 is still limited. We tested the prediction potentials of two different in silico methods for the identification of SARS-CoV-2 3CLpro cleavage sites in human proteins. Short stretches of homologous host-pathogen protein sequences (SSHHPS) that are present in SARS-CoV-2 polyprotein and human proteins were identified using BLAST analysis, and the NetCorona 1.0 webserver was used to successfully predict cleavage sites, although this method was primarily developed for SARS-CoV. Human C-terminal-binding protein 1 (CTBP1) was found to be cleaved in vitro by SARS-CoV-2 3CLpro, the existence of the cleavage site was proved experimentally by using a His6-MBP-mEYFP recombinant substrate containing the predicted target sequence. Our results highlight both potentials and limitations of the tested algorithms. The identification of candidate host substrates of 3CLpro may help better develop an understanding of the molecular mechanisms behind the replication and pathogenesis of SARS-CoV-2.
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Bozóki B, Mótyán JA, Hoffka G, Waugh DS, Tőzsér J. Specificity Studies of the Venezuelan Equine Encephalitis Virus Non-Structural Protein 2 Protease Using Recombinant Fluorescent Substrates. Int J Mol Sci 2020; 21:E7686. [PMID: 33081394 PMCID: PMC7593941 DOI: 10.3390/ijms21207686] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 10/13/2020] [Accepted: 10/14/2020] [Indexed: 11/16/2022] Open
Abstract
The non-structural protein 2 (nsP2) of alphavirus Venezuelan equine encephalitis virus (VEEV) is a cysteine protease that is responsible for processing of the viral non-structural polyprotein and is an important drug target owing to the clinical relevance of VEEV. In this study we designed two recombinant VEEV nsP2 constructs to study the effects of an N-terminal extension on the protease activity and to investigate the specificity of the elongated enzyme in vitro. The N-terminal extension was found to have no substantial effect on the protease activity. The amino acid preferences of the VEEV nsP2 protease were investigated on substrates representing wild-type and P5, P4, P2, P1, P1', and P2' variants of Semliki forest virus nsP1/nsP2 cleavage site, using a His6-MBP-mEYFP recombinant substrate-based protease assay which has been adapted for a 96-well plate-based format. The structural basis of enzyme specificity was also investigated in silico by analyzing a modeled structure of VEEV nsP2 complexed with oligopeptide substrate. To our knowledge, in vitro screening of P1' amino acid preferences of VEEV nsP2 protease remains undetermined to date, thus, our results may provide valuable information for studies and inhibitor design of different alphaviruses or other Group IV viruses.
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Affiliation(s)
- Beáta Bozóki
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (B.B.); (G.H.)
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - János András Mótyán
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (B.B.); (G.H.)
| | - Gyula Hoffka
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (B.B.); (G.H.)
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary
- MTA-DE Laboratory of Protein Dynamics, Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - David S. Waugh
- Macromolecular Crystallography Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA;
| | - József Tőzsér
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (B.B.); (G.H.)
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Biochemical Characterization of Human Retroviral-Like Aspartic Protease 1 (ASPRV1). Biomolecules 2020; 10:biom10071004. [PMID: 32640672 PMCID: PMC7408472 DOI: 10.3390/biom10071004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/26/2020] [Accepted: 06/30/2020] [Indexed: 12/25/2022] Open
Abstract
The human retroviral-like aspartic protease 1 (ASPRV1) is a mammalian retroviral-like enzyme that catalyzes a critical proteolytic step during epidermal differentiation; therefore, it is also referred to as skin-specific aspartic protease (SASPase). Neutrophil granulocytes were also found recently to express ASPRV1 that is involved in the progression of acute chronic inflammation of the central nervous system, especially in autoimmune encephalomyelitis. Thus, investigation of ASPRV1 is important due to its therapeutic or diagnostic potential. We investigated the structural characteristics of ASPRV1 by homology modeling; analysis of the proposed structure was used for interpretation of in vitro specificity studies. For in-vitro characterization, activities of SASP28 and SASP14 enzyme forms were measured using synthetic oligopeptide substrates. We demonstrated that self-processing of SASP28 precursor causes autoactivation of the protease. The highest activity was measured for GST-SASP14 at neutral pH and at high ionic strength, and we proved that pepstatin A and acetyl-pepstatin can also inhibit the protease. In agreement with the structural characteristics, the relatively lower urea dissociation constant implied lower dimer stability of SASP14 compared to that of HIV-1 protease. The obtained structural and biochemical characteristics support better understanding of ASPRV1 function in the skin and central nervous system.
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Golda M, Mótyán JA, Mahdi M, Tőzsér J. Functional Study of the Retrotransposon-Derived Human PEG10 Protease. Int J Mol Sci 2020; 21:ijms21072424. [PMID: 32244497 PMCID: PMC7212762 DOI: 10.3390/ijms21072424] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 12/11/2022] Open
Abstract
Paternally expressed gene 10 (PEG10) is a human retrotransposon-derived imprinted gene. The mRNA of PEG10 encodes two protein isoforms: the Gag-like protein (RF1PEG10) is coded by reading frame 1, while the Gag-Pol-like polyprotein (RF1/RF2PEG10) is coded by reading frames 1 and 2. The proteins are translated by a typical retroviral frameshift mechanism. The protease (PR) domain of RF2PEG10 contains an -Asp-Ser-Gly- sequence, which corresponds to the consensus -Asp-Ser/Thr-Gly- active-site motif of retroviral aspartic proteases. The function of the aspartic protease domain of RF2PEG10 remains unclear. To elucidate the function of PEG10 protease (PRPEG10), we designed a frameshift mutant (fsRF1/RF2PEG10) for comparison with the RF1/RF2PEG10 form. To study the effects of PRPEG10 on cellular proliferation and viability, mammalian HEK293T and HaCaT cells were transfected with plasmids coding for either RF1/RF2PEG10, the frameshift mutant (fsRF1/RF2PEG10), or a PR active-site (D370A) mutant fsRF1/RF2PEG10. Our results indicate that fsRF1/RF2PEG10 overexpression results in increased cellular proliferation. Remarkably, transfection with fsRF1/RF2PEG10 had a detrimental effect on cell viability. We hypothesize that PRPEG10 plays an important role in the function of this retroviral remnant, mediating the proliferation of cells and possibly implicating it in the inhibition of apoptosis.
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Affiliation(s)
- Mária Golda
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.G.); (M.M.)
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - János András Mótyán
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.G.); (M.M.)
- Correspondence: (J.A.M.); (J.T.)
| | - Mohamed Mahdi
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.G.); (M.M.)
| | - József Tőzsér
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.G.); (M.M.)
- Correspondence: (J.A.M.); (J.T.)
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