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Fló M, Carrión F, Olivero-Deibe N, Bianchi S, Portela M, Rammauro F, Alvarez B, Pritsch O. Kinetics of Bovine leukemia virus aspartic protease reveals its dimerization and conformational change. PLoS One 2022; 17:e0271671. [PMID: 35867649 PMCID: PMC9307154 DOI: 10.1371/journal.pone.0271671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 07/05/2022] [Indexed: 11/28/2022] Open
Abstract
The retropepsin (PR) of the Bovine leukemia virus (BLV) plays, as in other retroviruses, a crucial role in the transition from the non-infective viral particle to the infective virion by processing the polyprotein Gag. PR is expressed as an immature precursor associated with Gag, after an occasional −1 ribosomal frameshifting event. Self-hydrolysis of PR at specific N- and C-terminal sites releases the monomer that dimerizes giving rise to the active protease. We designed a strategy to express BLV PR in E. coli as a fusion protein with maltose binding protein, with a six-histidine tag at its N-terminal end, and bearing a tobacco etch virus protease hydrolysis site. This allowed us to obtain soluble and mature recombinant PR in relatively good yields, with exactly the same amino acid composition as the native protein. As PR presents relative promiscuity for the hydrolysis sites we designed four fluorogenic peptide substrates based on Förster resonance energy transfer (FRET) in order to characterize the activity of the recombinant enzyme. These substrates opened the way to perform kinetic studies, allowing us to characterize the dimer-monomer equilibrium. Furthermore, we obtained kinetic evidence for the existence of a conformational change that enables the interaction with the substrate. These results constitute a starting point for the elucidation of the kinetic properties of BLV-PR, and may be relevant not only to improve the chemical warfare against this virus but also to better understand other viral PRs.
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Affiliation(s)
- Martín Fló
- Laboratorio de Inmunovirología, Institut Pasteur de Montevideo, Montevideo, Uruguay
- Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
- * E-mail: (OP); (MF)
| | - Federico Carrión
- Laboratorio de Inmunovirología, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | | | - Sergio Bianchi
- Laboratorio de Inmunovirología, Institut Pasteur de Montevideo, Montevideo, Uruguay
- Laboratorio de Biomarcadores Moleculares, Departamento de Fisiopatología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Madelón Portela
- Unidad de Bioquímica y Proteómica Analíticas, Institut Pasteur de Montevideo, Facultad de Ciencias, Montevideo, Uruguay
| | - Florencia Rammauro
- Laboratorio de Inmunovirología, Institut Pasteur de Montevideo, Montevideo, Uruguay
- Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Beatriz Alvarez
- Laboratorio de Enzimología, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Otto Pritsch
- Laboratorio de Inmunovirología, Institut Pasteur de Montevideo, Montevideo, Uruguay
- Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
- * E-mail: (OP); (MF)
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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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3
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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: 12] [Impact Index Per Article: 3.0] [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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5
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Dimer Interface Organization is a Main Determinant of Intermonomeric Interactions and Correlates with Evolutionary Relationships of Retroviral and Retroviral-Like Ddi1 and Ddi2 Proteases. Int J Mol Sci 2020; 21:ijms21041352. [PMID: 32079302 PMCID: PMC7072860 DOI: 10.3390/ijms21041352] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/11/2020] [Accepted: 02/14/2020] [Indexed: 02/07/2023] Open
Abstract
The life cycles of retroviruses rely on the limited proteolysis catalyzed by the viral protease. Numerous eukaryotic organisms also express endogenously such proteases, which originate from retrotransposons or retroviruses, including DNA damage-inducible 1 and 2 (Ddi1 and Ddi2, respectively) proteins. In this study, we performed a comparative analysis based on the structural data currently available in Protein Data Bank (PDB) and Structural summaries of PDB entries (PDBsum) databases, with a special emphasis on the regions involved in dimerization of retroviral and retroviral-like Ddi proteases. In addition to Ddi1 and Ddi2, at least one member of all seven genera of the Retroviridae family was included in this comparison. We found that the studied retroviral and non-viral proteases show differences in the mode of dimerization and density of intermonomeric contacts, and distribution of the structural characteristics is in agreement with their evolutionary relationships. Multiple sequence and structure alignments revealed that the interactions between the subunits depend mainly on the overall organization of the dimer interface. We think that better understanding of the general and specific features of proteases may support the characterization of retroviral-like proteases.
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Gazda LD, Joóné Matúz K, Nagy T, Mótyán JA, Tőzsér J. Biochemical characterization of Ty1 retrotransposon protease. PLoS One 2020; 15:e0227062. [PMID: 31917798 PMCID: PMC6952103 DOI: 10.1371/journal.pone.0227062] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 12/10/2019] [Indexed: 01/08/2023] Open
Abstract
Ty1 is one of the many transposons in the budding yeast Saccharomyces cerevisiae. The life-cycle of Ty1 shows numerous similarities with that of retroviruses, e.g. the initially synthesized polyprotein precursor undergoes proteolytic processing by the protease. The retroviral proteases have become important targets of current antiretroviral therapies due to the critical role of the limited proteolysis of Gag-Pol polyprotein in the replication cycle and they therefore belong to the most well-studied enzymes. Comparative analyses of retroviral and retroviral-like proteases can help to explore the key similarities and differences which may help understanding how resistance is developed against protease inhibitors, but the available information about the structural and biochemical characteristics of retroviral-like, and especially retrotransposon, proteases is limited. To investigate the main characteristics of Ty1 retrotransposon protease of Saccharomyces cerevisiae, untagged and His6-tagged forms of Ty1 protease were expressed in E. coli. After purification of the recombinant proteins, activity measurements were performed using synthetic oligopeptide and fluorescent recombinant protein substrates, which represented the wild-type and the modified forms of naturally occurring cleavage sites of the protease. We investigated the dependence of enzyme activity on different reaction conditions (pH, temperature, ionic strength, and urea concentration), and determined enzyme kinetic parameters for the studied substrates. Inhibitory potentials of 10 different protease inhibitors were also tested. Ty1 protease was not inhibited by the inhibitors which have been designed against human immunodeficiency virus type 1 protease and are approved as antiretroviral therapeutics. A quaternary structure of homodimeric Ty1 protease was proposed based on homology modeling, and this structure was used to support interpretation of experimental results and to correlate some structural and biochemical characteristics with that of other retroviral proteases.
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Affiliation(s)
- Lívia Diána Gazda
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Krisztina Joóné Matúz
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tibor Nagy
- Department of Applied Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - János András Mótyán
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- * E-mail: (JAM); (JT)
| | - József Tőzsér
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- * E-mail: (JAM); (JT)
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7
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Wöhrl BM. Structural and Functional Aspects of Foamy Virus Protease-Reverse Transcriptase. Viruses 2019; 11:v11070598. [PMID: 31269675 PMCID: PMC6669543 DOI: 10.3390/v11070598] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 06/28/2019] [Accepted: 06/29/2019] [Indexed: 12/15/2022] Open
Abstract
Reverse transcription describes the process of the transformation of single-stranded RNA into double-stranded DNA via an RNA/DNA duplex intermediate, and is catalyzed by the viral enzyme reverse transcriptase (RT). This event is a pivotal step in the life cycle of all retroviruses. In contrast to orthoretroviruses, the domain structure of the mature RT of foamy viruses is different, i.e., it harbors the protease (PR) domain at its N-terminus, thus being a PR-RT. This structural feature has consequences on PR activation, since the enzyme is monomeric in solution and retroviral PRs are only active as dimers. This review focuses on the structural and functional aspects of simian and prototype foamy virus reverse transcription and reverse transcriptase, as well as special features of reverse transcription that deviate from orthoretroviral processes, e.g., PR activation.
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Affiliation(s)
- Birgitta M Wöhrl
- Lehrstuhl Biopolymere, Universität Bayreuth, D-95440 Bayreuth, Germany.
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8
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Spannaus R, Bodem J. Determination of the protease cleavage site repertoire--the RNase H but not the RT domain is essential for foamy viral protease activity. Virology 2014; 454-455:145-56. [PMID: 24725941 DOI: 10.1016/j.virol.2014.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 12/15/2013] [Accepted: 02/11/2014] [Indexed: 12/26/2022]
Abstract
In contrast to orthoretroviruses, the foamy virus protease is only active as a protease-reverse transcriptase fusion protein and requires viral RNA for activation. Maturation of foamy viral proteins seems to be restricted to a single cleavage site in Gag and Pol. We provide evidence that unprocessed Gag is required for optimal infectivity, which is unique among retroviruses. Analyses of the cleavage site sequences of the Gag and Pol cleavage sites revealed a high similarity compared to those of Lentiviruses. We show that positions P2׳ and P2 are invariant and that Gag and Pol cleavage sites are processed with similar efficiencies. The RNase H domain is essential for protease activity, but can functionally be substituted by RNase H domains of other retroviruses. Thus, the RNase H domain might be involved in the stabilization of the protease dimer, while the RT domain is essential for RNA dependent protease activation.
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Affiliation(s)
- Ralf Spannaus
- Universität Würzburg, Institut für Virologie und Immunbiologie, Versbacher Str. 7, 97078 Würzburg, Germany
| | - Jochen Bodem
- Universität Würzburg, Institut für Virologie und Immunbiologie, Versbacher Str. 7, 97078 Würzburg, Germany.
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9
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Comparative studies on retroviral proteases: substrate specificity. Viruses 2010; 2:147-165. [PMID: 21994605 PMCID: PMC3185560 DOI: 10.3390/v2010147] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 01/12/2010] [Accepted: 01/13/2010] [Indexed: 12/18/2022] Open
Abstract
Exogenous retroviruses are subclassified into seven genera and include viruses that cause diseases in humans. The viral Gag and Gag-Pro-Pol polyproteins are processed by the retroviral protease in the last stage of replication and inhibitors of the HIV-1 protease are widely used in AIDS therapy. Resistant mutations occur in response to the drug therapy introducing residues that are frequently found in the equivalent position of other retroviral proteases. Therefore, besides helping to understand the general and specific features of these enzymes, comparative studies of retroviral proteases may help to understand the mutational capacity of the HIV-1 protease.
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10
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Amino acid preferences of retroviral proteases for amino-terminal positions in a type 1 cleavage site. J Virol 2008; 82:10111-7. [PMID: 18701588 DOI: 10.1128/jvi.00418-08] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The specificities of the proteases of 11 retroviruses were studied using a series of oligopeptides with amino acid substitutions in the P1, P3, and P4 positions of a naturally occurring type 1 cleavage site (Val-Ser-Gln-Asn-Tyr downward arrowPro-Ile-Val-Gln) in human immunodeficiency virus type 1 (HIV-1). Previously, the substrate specificity of the P2 site was studied for the same representative set of retroviral proteases, which included at least one member from each of the seven genera of the family Retroviridae (P. Bagossi, T. Sperka, A. Fehér, J. Kádas, G. Zahuczky, G. Miklóssy, P. Boross, and J. Tözsér, J. Virol. 79:4213-4218, 2005). Our enzyme set comprised the proteases of HIV-1, HIV-2, equine infectious anemia virus, avian myeloblastosis virus (AMV), Mason-Pfizer monkey virus, mouse mammary tumor virus (MMTV), Moloney murine leukemia virus, human T-lymphotropic virus type 1, bovine leukemia virus, walleye dermal sarcoma virus, and human foamy virus. Molecular models were used to interpret the similarities and differences in specificity between these retroviral proteases. The results showed that the retroviral proteases had similar preferences (Phe and Tyr) for the P1 position in this sequence context, but differences were found for the P3 and P4 positions. Importantly, the sizes of the P3 and P4 residues appear to be a major contributor for specificity. The substrate specificities correlated well with the phylogenetic tree of the retroviruses. Furthermore, while the specificities of some enzymes belonging to different genera appeared to be very similar (e.g., those of AMV and MMTV), the specificities of the primate lentiviral proteases substantially differed from that observed for a nonprimate lentiviral protease.
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11
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Hartl MJ, Wöhrl BM, Rösch P, Schweimer K. The solution structure of the simian foamy virus protease reveals a monomeric protein. J Mol Biol 2008; 381:141-9. [PMID: 18597783 DOI: 10.1016/j.jmb.2008.05.064] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Revised: 05/23/2008] [Accepted: 05/27/2008] [Indexed: 10/22/2022]
Abstract
In contrast to orthoretroviruses, foamy viruses (FVs) express their Pol polyprotein from a separate pol-specific transcript. Only the integrase domain is cleaved off, leading to a protease-reverse transcriptase (PR-RT) protein. We purified the separate PR domain (PRshort) of simian FV from macaques by expressing the recombinant gene in Escherichia coli. Sedimentation analyses and size exclusion chromatography indicate that PRshort is a stable monomer in solution. This allowed us to determine the structure of the PRshort monomer using 1426 experimental restraints derived from NMR spectroscopy. The superposition of 20 conformers resulted in a backbone atom rmsd of 0.55 A for residues Gln8-Leu93. Although the overall folds are similar, the macaque simian FV PRshort reveals significant differences in the dimerization interface relative to other retroviral PRs, such as HIV-1 (human immunodeficiency virus type 1) PR, which appear to be rather stable dimers. Especially the flap region and the N- and C-termini of PRshort are highly flexible. Neglecting these regions, the backbone atom rmsd drops to 0.32 A, highlighting the good definition of the central part of the protein. To exclude that the monomeric state of PRshort is due to cleaving off the RT, we purified the complete PR-RT and performed size exclusion chromatography. Our data show that PR-RT is also monomeric. We thus conclude adoption of a monomeric state of PR-RT to be a regulatory mechanism to inhibit PR activity before virus assembly in order to reduce packaging problems. Dimerization might therefore be triggered by additional viral or cellular factors.
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Affiliation(s)
- Maximilian J Hartl
- Lehrstuhl für Struktur und Chemie der Biopolymere, Universität Bayreuth, 95440 Bayreuth, Germany
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12
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Sperka T, Miklóssy G, Tie Y, Bagossi P, Zahuczky G, Boross P, Matúz K, Harrison RW, Weber IT, Tözsér J. Bovine leukemia virus protease: comparison with human T-lymphotropic virus and human immunodeficiency virus proteases. J Gen Virol 2007; 88:2052-2063. [PMID: 17554040 DOI: 10.1099/vir.0.82704-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Bovine leukemia virus (BLV) is a valuable model system for understanding human T-lymphotropic virus 1 (HTLV-1); the availability of an infectious BLV clone, together with animal-model systems, will help to explore anti-HTLV-1 strategies. Nevertheless, the specificity and inhibitor sensitivity of the BLV protease (PR) have not been characterized in detail. To facilitate such studies, a molecular model for the enzyme was built. The specificity of the BLV PR was studied with a set of oligopeptides representing naturally occurring cleavage sites in various retroviruses. Unlike HTLV-1 PR, but similar to the human immunodeficiency virus 1 (HIV-1) enzyme, BLV PR was able to hydrolyse the majority of the peptides, mostly at the same position as did their respective host PRs, indicating a broad specificity. When amino acid residues of the BLV PR substrate-binding sites were replaced by equivalent ones of the HIV-1 PR, many substitutions resulted in inactive protein, indicating a great sensitivity to mutations, as observed previously for the HTLV-1 PR. The specificity of the enzyme was studied further by using a series of peptides containing amino acid substitutions in a sequence representing a naturally occurring HTLV-1 PR cleavage site. Also, inhibitors of HIV-1 PR, HTLV-1 PR and other retroviral proteases were tested on the BLV PR. Interestingly, the BLV PR was more susceptible than the HTLV-1 PR to the inhibitors tested. Therefore, despite the specificity differences, in terms of mutation intolerance and inhibitor susceptibility of the PR, BLV and the corresponding animal-model systems may provide good models for testing of PR inhibitors that target HTLV-1.
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Affiliation(s)
- Tamás Sperka
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Hungary
| | - Gabriella Miklóssy
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Hungary
| | - Yunfeng Tie
- Department of Chemistry, Georgia State University, Atlanta, GA, USA
| | - Péter Bagossi
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Hungary
| | - Gábor Zahuczky
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Hungary
| | - Péter Boross
- Department of Biology, Georgia State University, Atlanta, GA, USA
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Hungary
| | - Krisztina Matúz
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Hungary
| | - Robert W Harrison
- Department of Computer Science, Georgia State University, Atlanta, GA, USA
- Department of Biology, Georgia State University, Atlanta, GA, USA
| | - Irene T Weber
- Department of Biology, Georgia State University, Atlanta, GA, USA
- Department of Chemistry, Georgia State University, Atlanta, GA, USA
| | - József Tözsér
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Hungary
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Boross P, Tözsér J, Bagossi P. Improved purification protocol for wild-type and mutant human foamy virus proteases. Protein Expr Purif 2005; 46:343-7. [PMID: 16243539 DOI: 10.1016/j.pep.2005.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 09/06/2005] [Accepted: 09/09/2005] [Indexed: 10/25/2022]
Abstract
Wild-type and an active site mutant (S25T) human foamy virus (HFV) proteases were expressed in fusion with maltose binding protein in Escherichia coli. The mutant enzyme contained a Ser to Thr mutation in the -Asp-Ser-Gly- active site triplet of the enzyme, which forms the "fireman's grip" between the two subunits of the homodimeric enzyme. The fusion proteins were purified by affinity chromatography on amylose resin, cleaved with factor Xa, and the processed enzymes were purified by gel filtration under denaturing condition. Refolding after purification resulted in active enzymes with comparable yields. Furthermore, both enzymes showed similar catalytic activities in an oligopeptide substrate representing an HFV Gag cleavage site. However, the S25T mutant showed increased stability in urea unfolding experiment, in a good agreement with the suggested role of the Thr residue of fireman's grip.
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Affiliation(s)
- Péter Boross
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, H-4012 Debrecen, Nagyerdei krt. 98., P.O. Box 6, Hungary
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14
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Bagossi P, Sperka T, Fehér A, Kádas J, Zahuczky G, Miklóssy G, Boross P, Tözsér J. Amino acid preferences for a critical substrate binding subsite of retroviral proteases in type 1 cleavage sites. J Virol 2005; 79:4213-8. [PMID: 15767422 PMCID: PMC1061542 DOI: 10.1128/jvi.79.7.4213-4218.2005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Accepted: 10/31/2004] [Indexed: 11/20/2022] Open
Abstract
The specificities of the proteases of 11 retroviruses representing each of the seven genera of the family Retroviridae were studied using a series of oligopeptides with amino acid substitutions in the P2 position of a naturally occurring type 1 cleavage site (Val-Ser-Gln-Asn-Tyr Pro-Ile-Val-Gln; the arrow indicates the site of cleavage) in human immunodeficiency virus type 1 (HIV-1). This position was previously found to be one of the most critical in determining the substrate specificity differences of retroviral proteases. Specificities at this position were compared for HIV-1, HIV-2, equine infectious anemia virus, avian myeloblastosis virus, Mason-Pfizer monkey virus, mouse mammary tumor virus, Moloney murine leukemia virus, human T-cell leukemia virus type 1, bovine leukemia virus, human foamy virus, and walleye dermal sarcoma virus proteases. Three types of P2 preferences were observed: a subgroup of proteases preferred small hydrophobic side chains (Ala and Cys), and another subgroup preferred large hydrophobic residues (Ile and Leu), while the protease of HIV-1 preferred an Asn residue. The specificity distinctions among the proteases correlated well with the phylogenetic tree of retroviruses prepared solely based on the protease sequences. Molecular models for all of the proteases studied were built, and they were used to interpret the results. While size complementarities appear to be the main specificity-determining features of the S2 subsite of retroviral proteases, electrostatic contributions may play a role only in the case of HIV proteases. In most cases the P2 residues of naturally occurring type 1 cleavage site sequences of the studied proteases agreed well with the observed P2 preferences.
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Affiliation(s)
- Péter Bagossi
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
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15
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Fehér A, Boross P, Sperka T, Oroszlan S, Tözsér J. Expression of the murine leukemia virus protease in fusion with maltose-binding protein in Escherichia coli. Protein Expr Purif 2004; 35:62-8. [PMID: 15039067 DOI: 10.1016/j.pep.2004.01.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2003] [Revised: 01/12/2004] [Indexed: 01/15/2023]
Abstract
The protease of murine leukemia virus (MLV) was cloned into pMal-c2 vector, expressed in fusion with maltose-binding protein (MBP), and purified to homogeneity after Factor Xa cleavage of the chimeric protein. Substantial degradation of the fusion protein was observed during expression, which severely diminished the yield. The degree of degradation of the fusion protein was even more pronounced when a single-chain form of the MLV protease was cloned after the gene coding for MBP. To increase the yield, a hexahistidine tag with an additional Factor Xa cleavage site was cloned after the protease and nickel chelate affinity chromatography was used as the first purification step. The modified procedure resulted in substantially higher yield as compared to the original procedure. The degradation of hexahistidine-tagged active site mutant MLV protease was very low and comparable to that obtained with hexahistidine-tagged MBP, but purified MLV protease alone was not able to degrade purified MBP, suggesting that during expression the active MLV protease may activate bacterial proteases which appear to be responsible for the degradation of the fusion proteins.
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Affiliation(s)
- Anita Fehér
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
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16
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Abstract
The foamy viral proteases (FV PRs) are set apart from other retroviral processing enzymes by unique features. The first remarkable property is that FV PRs are enzymatically active as high-molecular-mass Pro-Pol proteins. Hence there exist multiple forms of active FV PRs that likely contribute to cleavage site specificity. A FV PR of low molecular size is not detectable in purified virions, in contrast to PRs of other retroviruses that are found in virus particles. Because the major part of Pol remains attached to the amino-terminal enzymatically active PR protein region, the FV-specific way of expressing Pro-Pol polyproteins from a pol-specific transcript provides for the incorporation of Pro-Pol and IN into virus particles. Proteolytic processing of Gag and Pol proteins is incomplete and delayed. Another novel feature is that the catalytic center of the active dimers of cat FV PR consists of D-S/T-Q instead of D-S/T-G, an unprecedented feature of this enzyme. The temporal and spatial control and the factors that regulate FV PRs remain to be elucidated.
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MESH Headings
- Amino Acid Sequence
- Animals
- Aspartic Acid Endopeptidases/biosynthesis
- Aspartic Acid Endopeptidases/genetics
- Aspartic Acid Endopeptidases/metabolism
- Fusion Proteins, gag-pol/biosynthesis
- Fusion Proteins, gag-pol/genetics
- Fusion Proteins, gag-pol/metabolism
- Gene Expression Regulation, Viral
- Gene Products, env/genetics
- Gene Products, env/physiology
- Gene Products, gag/biosynthesis
- Gene Products, gag/metabolism
- Gene Products, pol/biosynthesis
- Gene Products, pol/metabolism
- Humans
- Molecular Sequence Data
- Mutation
- Polyproteins/chemistry
- Polyproteins/physiology
- Protein Processing, Post-Translational
- Rabbits
- Spumavirus/enzymology
- Spumavirus/genetics
- Spumavirus/physiology
- Virion/physiology
- Virus Assembly
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Affiliation(s)
- R M Flügel
- Retroviral Gene Expression, Research Programme Applied Tumor Virology, German Cancer Research Center, Im Neuenheimer Feld 242, 69009 Heidelberg, Germany.
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17
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Pfrepper KI, Reed J, Rackwitz HR, Schnölzer M, Flügel RM. Characterization of peptide substrates and viral enzyme that affect the cleavage site specificity of the human spumaretrovirus proteinase. Virus Genes 2001; 22:61-72. [PMID: 11210941 DOI: 10.1023/a:1008134419542] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Oligopeptides that correspond to proteolytic cleavage site junctions of the native Gag and Pol proteins are specifically cleaved by retroviral aspartate proteases (PRs). The role of the flap subdomain of the PR of the human spumaretrovirus (HSRV) and of substrate peptides in cleavage site specificity was analyzed by site-directed mutagenesis. Native and mutant peptides were subjected to proteolysis by the authentic and mutated recombinant viral enzyme. The results reveal that Glu residue 54 of the HSRV PR is an essential specificity determinant for proteolytic processing of the structural proteins. Peptides that represent in vivo cleavage sites were susceptible to proteolysis by the recombinant HSRV PR, but one peptide located at the junction between the PR and reverse transcriptase domains was completely resistant to cleavage. Thus the data indicate that a proteolytic cleavage between these domains does not occur in vivo. Naturally occurring and mutant forms of the cleavage-resistant peptide were therefore analyzed by circular dichroism to determine if differences existed in the secondary structures of the peptides that did or did not serve as substrates. The data show that differences in the secondary structure of the native and mutant peptides analyzed does not seem to play a crucial role for cleavage site specificity in HSRV PR. Instead highly conserved hydrophobic residues at distinct positions of the HSRV cleavage site junctions contribute to the specificity observed as reported for HIV-1 PR.
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Affiliation(s)
- K I Pfrepper
- Division of Retroviral Gene Expression, German Cancer Research Center, Heidelberg, Federal Republic of Germany
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