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1.

001-es BibID:BIBFORM040648
Első szerző:Boross Péter (biokémikus, vegyész)
Cím:Effect of substrate residues on the P2' preference of retroviral proteinases / Boross Peter, Bagossi Peter, Copeland Terry D., Oroszlan Stephen, Louis John M., Tozser Jozsef
Dátum:1999
ISSN:0014-2956
Megjegyzések:The substrate sequence requirements for preference toward P2' Glu residue by human immunodeficiency virus type 1 (HIV-1) proteinase were studied in both the matrix protein/ capsid protein (MA/CA) and CA/p2 cleavage site sequence contexts. These sequences represent typical type 1 (-aromatic*Pro-) and type 2 (-hydrophobic* hydrophobic-) cleavage site sequences, respectively. While in the type 1 sequence context, the preference for P2' Glu over Ile or Gln was found to be strongly dependent on the ionic strength and the residues being outside the P2-P2' region of the substrate, it remained preferable in the type 2 substrates when typical type 1 substrate sequence residues were substituted into the outside regions. The pH profile of the specificity constants suggested a lower pH optimum for substrates having P2' Glu in contrast to those having uncharged residues, in both sequence contexts. The very low frequency of P2' Glu in naturally occurring retroviral cleavage sites of various retroviruses including equine infectious anemia virus (EIAV) and murine leukemia virus (MuLV) suggests that such a residue may not have a general regulatory role in the retroviral life cycle. In fact, unlike HIV-1 and HIV-2, EIAV and MuLV proteinases do not favor P2' Glu in either the MA/CA or CA/p2 sequence contexts.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:European Journal Of Biochemistry. - 264 : 3 (1999), p. 921-929. -
További szerzők:Bagossi Péter (1966-2011) (biokémikus, vegyész) Copeland, Terry D. Oroszlan, Stephen Louis, John M. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész)
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2.

001-es BibID:BIBFORM040655
Első szerző:Fehér Anita
Cím:Effect of sequence polymorphism and drug resistance on two HIV-1 Gag processing sites / Fehér Anita, Weber Irene T., Bagossi Péter, Boross Péter, Mahalingam Bhuvaneshwari, Louis John M., Copeland Terry D., Torshin Ivan Y., Harrison Robert W., Tözsér József
Dátum:2002
ISSN:0014-2956
Megjegyzések:The HIV-1 proteinase (PR) has proved to be a good target for antiretroviral therapy of AIDS, and various PR inhibitors are now in clinical use. However, there is a rapid selection of viral variants bearing mutations in the proteinase that are resistant to clinical inhibitors. Drug resistance also involves mutations of the nucleocapsid/p1 and p1/p6 cleavage sites of Gag, both in vitro and in vivo. Cleavages at these sites have been shown to be rate limiting steps for polyprotein processing and viral maturation. Furthermore, these sites show significant sequence polymorphism, which also may have an impact on virion infectivity. We have studied the hydrolysis of oligopeptides representing these cleavage sites with representative mutations found as natural variations or that arise as resistant mutations. Wild-type and five drug resistant PRs with mutations within or outside the substrate binding site were tested. While the natural variations showed either increased or decreased susceptibility of peptides toward the proteinases, the resistant mutations always had a beneficial effect on catalytic efficiency. Comparison of the specificity changes obtained for the various substrates suggested that the maximization of the van der Waals contacts between substrate and PR is the major determinant of specificity: the same effect is crucial for inhibitor potency. The natural nucleocapsid/p1 and p1/p6 sites do not appear to be optimized for rapid hydrolysis. Hence, mutation of these rate limiting cleavage sites can partly compensate for the reduced catalytic activity of drug resistant mutant HIV-1 proteinases.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:European Journal Of Biochemistry. - 269 : 16 (2002), p. 4114-4120. -
További szerzők:Weber, Irene T. Bagossi Péter (1966-2011) (biokémikus, vegyész) Boross Péter (1972-) (biokémikus, vegyész) Mahalingam, Bhuvaneshwari Louis, John M. Copeland, Terry D. Torshin, Ivan Y. Harrison, Robert W. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész)
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3.

001-es BibID:BIBFORM086386
Első szerző:Liu, Fengling
Cím:Analysis of HIV-1 protease mutants to understand mechanisms of resistance / Liu F., Boross Péter, Tőzsér József, Louis J. M., Harrison R. W., Weber I. T.
Dátum:2005
ISSN:1742-464X
Tárgyszavak:Orvostudományok Klinikai orvostudományok idézhető absztrakt
folyóiratcikk
Megjelenés:Febs Journal. - 272 : Suppl1 (2005), p. 12. -
További szerzők:Boross Péter (1972-) (biokémikus, vegyész) Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Louis, John M. Harrison, Robert W. Weber, Irene T.
Pályázati támogatás:OTKA T43482
OTKA
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4.

001-es BibID:BIBFORM040663
Első szerző:Liu, Fengling
Cím:Kinetic, Stability, and Structural Changes in High-resolution Crystal Structures of HIV-1 Protease with Drug-resistant Mutations L24I, I50V, and G73S / Liu Fengling, Boross Peter I., Wang Yuan-Fang, Tozser Jozsef, Louis John M., Harrison Robert W., Weber Irene T.
Dátum:2005
ISSN:0022-2836
Megjegyzések:The crystal structures, dimer stabilities, and kinetics have been analyzed for wild-type human immunodeficiency virus type 1 (HIV-1) protease (PR) and resistant mutants PR(L24I), PR(I50V), and PR(G73S) to gain insight into the molecular basis of drug resistance. The mutations lie in different structural regions. Mutation I50V alters a residue in the flexible flap that interacts with the inhibitor, L24I alters a residue adjacent to the catalytic Asp25, and G73S lies at the protein surface far from the inhibitor-binding site. PR(L24I) and PR(I50V), showed a 4% and 18% lower k(cat)/K(m), respectively, relative to PR. The relative k(cat)/K(m) of PR(G73S) varied from 14% to 400% when assayed using different substrates. Inhibition constants (K(i)) of the antiviral drug indinavir for the reaction catalyzed by the mutant enzymes were about threefold and 50-fold higher for PR(L24I) and PR(I50V), respectively, relative to PR and PR(G73S). The dimer dissociation constant (K(d)) was estimated to be approximately 20 nM for both PR(L24I) and PR(I50V), and below 5 nM for PR(G73S) and PR. Crystal structures of the mutants PR(L24I), PR(I50V) and PR(G73S) were determined in complexes with indinavir, or the p2/NC substrate analog at resolutions of 1.10-1.50 Angstrom. Each mutant revealed distinct structural changes relative to PR. The mutated residues in PR(L24I) and PR(I50V) had reduced intersubunit contacts, consistent with the increased K(d) for dimer dissociation. Relative to PR, PR(I50V) had fewer interactions of Val50 with inhibitors, in agreement with the dramatically increased K(i). The distal mutation G73S introduced new hydrogen bond interactions that can transmit changes to the substrate-binding site and alter catalytic activity. Therefore, the structural alterations observed for drug-resistant mutations were in agreement with kinetic and stability changes.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal Of Molecular Biology. - 354 : 4 (2005), p. 789-800. -
További szerzők:Boross Péter (1972-) (biokémikus, vegyész) Wang, Yuan-Fang Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Louis, John M. Harrison, Robert W. Weber, Irene T.
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5.

001-es BibID:BIBFORM019933
Első szerző:Liu, Fengling
Cím:Mechanism of drug resistance revealed by the crystal structure of the unliganded HIV-1 protease with F53L mutation / Fengling Liu, Andrey Y. Kovalevsky, John M. Louis, Peter I. Boross, Yuan-Fang Wang, Robert W. Harrison, Irene T. Weber
Dátum:2006
ISSN:0022-2836
Megjegyzések:Mutations in HIV-1 protease (PR) that produce resistance to antiviral PR inhibitors are a major problem in AIDS therapy. The mutation F53L arising from antiretroviral therapy was introduced into the flexible flap region of the wild-type PR to study its effect and potential role in developing drug resistance. Compared to wild-type PR, PR(F53L) showed lower (15%) catalytic efficiency, 20-fold weaker inhibition by the clinical drug indinavir, and reduced dimer stability, while the inhibition constants of two peptide analog inhibitors were slightly lower than those for PR. The crystal structure of PR(F53L) was determined in the unliganded form at 1.35 Angstrom resolution in space group P4(1)2(1)2. The tips of the flaps in PR(F53L) had a wider separation than in unliganded wild-type PR, probably due to the absence of hydrophobic interactions of the side-chains of Phe53 and Ile50'. The changes in interactions between the flaps agreed with the reduced stability of PR(F53L) relative to wild-type PR. The altered flap interactions in the unliganded form of PR(F53L) suggest a distinct mechanism for drug resistance, which has not been observed in other common drug-resistant mutants.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal of Molecular Biology. - 358 : 5 (2006), p. 1191-1199. -
További szerzők:Kovalevsky, Andrey Yu Louis, John M. Wang, Yuan-Fang Harrison, Robert W. Weber, Irene T. Boross Péter (1972-) (biokémikus, vegyész)
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6.

001-es BibID:BIBFORM040670
Első szerző:Mahalingam, Bhuvaneshwari
Cím:Combining mutations in HIV-1 protease to understand mechanisms of resistance / Mahalingam Bhuvaneshwari, Boross Peter, Wang Yuan-Fang, Louis John M., Fischer Christopher C., Tozser Jozsef, Harrison Robert W., Weber Irene T.
Dátum:2002
ISSN:0887-3585
Megjegyzések:HIV-1 develops resistance to protease inhibitors predominantly by selecting mutations in the protease gene. Studies of resistant mutants of HIV-1 protease with single amino acid substitutions have shown a range of independent effects on specificity, inhibition, and stability. Four double mutants, K45I/L90M, K45I/V82S, D30N/V82S, and N88D/L90M were selected for analysis on the basis of observations of increased or decreased stability or enzymatic activity for the respective single mutants. The double mutants were assayed for catalysis, inhibition, and stability. Crystal structures were analyzed for the double mutants at resolutions of 2.2-1.2 A to determine the associated molecular changes. Sequence-dependent changes in protease-inhibitor interactions were observed in the crystal structures. Mutations D30N, K45I, and V82S showed altered interactions with inhibitor residues at P2/P2', P3/P3'/P4/P4', and P1/P1', respectively. One of the conformations of Met90 in K45I/L90M has an unfavorably close contact with the carbonyl oxygen of Asp25, as observed previously in the L90M single mutant. The observed catalytic efficiency and inhibition for the double mutants depended on the specific substrate or inhibitor. In particular, large variation in cleavage of p6(pol)-PR substrate was observed, which is likely to result in defects in the maturation of the protease from the Gag-Pol precursor and hence viral replication. Three of the double mutants showed values for stability that were intermediate between the values observed for the respective single mutants. D30N/V82S mutant showed lower stability than either of the two individual mutations, which is possibly due to concerted changes in the central P2-P2' and S2-S2' sites. The complex effects of combining mutations are discussed.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Proteins-Structure Function And Bioinformatics. - 48 : 1 (2002), p. 107-116. -
További szerzők:Boross Péter (1972-) (biokémikus, vegyész) Wang, Yuan-Fang Louis, John M. Fischer, Christopher C. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Harrison, Robert W. Weber, Irene T.
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7.

001-es BibID:BIBFORM040668
Első szerző:Mahalingam, Bhuvaneshwari
Cím:Crystal structures of HIV protease V82A and L90M mutants reveal changes in the indinavir-binding site / Mahalingam Bhuvaneshwari, Wang Yuan-Fang, Boross Peter I., Tozser Jozsef, Louis John M., Harrison Robert W., Weber Irene T.
Dátum:2004
ISSN:0014-2956
Megjegyzések:The crystal structures of the wild-type HIV-1 protease (PR) and the two resistant variants, PR(V82A) and PR(L90M), have been determined in complex with the antiviral drug, indinavir, to gain insight into the molecular basis of drug resistance. V82A and L90M correspond to an active site mutation and nonactive site mutation, respectively. The inhibition (K(i)) of PR(V82A) and PR(L90M) was 3.3- and 0.16-fold, respectively, relative to the value for PR. They showed only a modest decrease, of 10-15%, in their k(cat)/K(m) values relative to PR. The crystal structures were refined to resolutions of 1.25-1.4 A to reveal critical features associated with inhibitor resistance. PR(V82A) showed local changes in residues 81-82 at the site of the mutation, while PR(L90M) showed local changes near Met90 and an additional interaction with indinavir. These structural differences concur with the kinetic data.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:European Journal Of Biochemistry. - 271 : 8 (2004), p. 1516-1524. -
További szerzők:Wang, Yuan-Fang Boross Péter (1972-) (biokémikus, vegyész) Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Louis, John M. Harrison, Robert W. Weber, Irene T.
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8.

001-es BibID:BIBFORM040679
Első szerző:Tie, Yunfeng
Cím:Critical differences in HIV-1 and HIV-2 protease specificity for clinical inhibitors / Tie Yunfeng, Wang Yuan-Fang, Boross Peter I., Chiu Ting-Yi, Ghosh Arun K., Tozser Jozsef, Louis John M., Harrison Robert W., Weber Irene T.
Dátum:2012
ISSN:0961-8368
Megjegyzések:Clinical inhibitor amprenavir (APV) is less effective on HIV-2 protease (PR₂) than on HIV-1 protease (PR₁). We solved the crystal structure of PR₂ with APV at 1.5 Å resolution to identify structural changes associated with the lowered inhibition. Furthermore, we analyzed the PR₁ mutant (PR(1M) ) with substitutions V32I, I47V, and V82I that mimic the inhibitor binding site of PR₂. PR(1M) more closely resembled PR₂ than PR₁ in catalytic efficiency on four substrate peptides and inhibition by APV, whereas few differences were seen for two other substrates and inhibition by saquinavir (SQV) and darunavir (DRV). High resolution crystal structures of PR(1M) with APV, DRV, and SQV were compared with available PR₁ and PR₂ complexes. Val/Ile32 and Ile/Val47 showed compensating interactions with SQV in PR(1M) and PR₁, however, Ile82 interacted with a second SQV bound in an extension of the active site cavity of PR(1M). Residues 32 and 82 maintained similar interactions with DRV and APV in all the enzymes, whereas Val47 and Ile47 had opposing effects in the two subunits. Significantly diminished interactions were seen for the aniline of APV bound in PR₁ (M) and PR₂ relative to the strong hydrogen bonds observed in PR₁, consistent with 15- and 19-fold weaker inhibition, respectively. Overall, PR(1M) partially replicates the specificity of PR₂ and gives insight into drug resistant mutations at residues 32, 47, and 82. Moreover, this analysis provides a structural explanation for the weaker antiviral effects of APV on HIV-2.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Protein Science. - 21 : 3 (2012), p. 339-350. -
További szerzők:Wang, Yuan-Fang Boross Péter (1972-) (biokémikus, vegyész) Chiu, Ting-Yi Ghosh, Arun K. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Louis, John M. Harrison, Robert W. Weber, Irene T.
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9.

001-es BibID:BIBFORM040690
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Effect of serine and tyrosine phosphorylation on retroviral proteinase substrates / Tozser Jozsef, Bagossi Peter, Boross Peter, Louis John M., Majerova Eva, Oroszlan Stephen, Copeland Terry D.
Dátum:1999
ISSN:0014-2956
Megjegyzések:Vimentin, a cellular substrate of HIV type 1 (HIV-1) proteinase, contains a protein kinase C (PKC) phosphorylation site at one of its cleavage sites. Peptides representing this site were synthesized in P2 Ser-phosphorylated and nonphosphorylated forms. While the nonphosphorylated peptide was a fairly good substrate of the enzyme, phosphorylation prevented hydrolysis. Phosphorylation of human recombinant vimentin by PKC prevented its processing within the head domain, where the phosphorylation occurred. Oligopeptides representing naturally occurring cleavage sites at the C-terminus of the Rous sarcoma virus integrase were assayed as substrates of the avian proteinase. Unlike the nonphosphorylated peptides, a Ser-phosphorylated peptide was not hydrolyzed by the enzyme at the Ser-Pro bond, suggesting the role of previously established phosphorylation in processing at this site. Ser-phosphorylated and Tyr-phosphorylated forms of model substrates were also tested as substrates of the HIV-1 and the avian retroviral proteinases. In contrast to the moderate effect of P4 Ser phosphorylation, phosphorylation of P1 Tyr prevented substrate hydrolysis by HIV-1 proteinase. Substrate phosphorylation had substantially smaller effects on the hydrolysis by the avian retroviral proteinase. As the active retroviral proteinase as well as various protein kinases are incorporated into mature virions, substrate phosphorylation resulting in attenuation or prevention of proteolytic processing may have important consequences in the regulation of the retroviral life cycle as well as in virus-host cell interactions.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:European Journal Of Biochemistry. - 265 : 1 (1999), p. 423-429. -
További szerzők:Bagossi Péter (1966-2011) (biokémikus, vegyész) Boross Péter (1972-) (biokémikus, vegyész) Louis, John M. Majerova, Eva Oroszlan, Stephen Copeland, Terry D.
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10.

001-es BibID:BIBFORM039225
Első szerző:Zahuczky Gábor (molekuláris biológus, biokémikus, vegyész)
Cím:Cloning of the bovine leukemia virus proteinase in Escherichia coli and comparison of its specificity to that of human T-cell leukemia virus proteinase / Gábor Zahuczky, Péter Boross, Péter Bagossi, Gabriella Emri, Terry D. Copeland, Stephen Oroszlan, John M. Louis, József Tőzsér
Dátum:2000
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Biochimica et Biophysica Acta (BBA). Protein Structure and Molecular Enzymology. - 1478 : 1 (2000), p. 1-8. -
További szerzők:Boross Péter (1972-) (biokémikus, vegyész) Bagossi Péter (1966-2011) (biokémikus, vegyész) Emri Gabriella (1972-) (bőrgyógyász, allergológus, onkológus) Copeland, Terry D. Oroszlan, Stephen Louis, John M. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész)
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