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Cheng BH, Zhou X, Wang Y, Chan JYW, Lin HQ, Or PMY, Wan DCC, Leung PC, Fung KP, Wang YF, Lau CBS. Herb-drug interaction between an anti-HIV Chinese herbal SH formula and atazanavir in vitro and in vivo. JOURNAL OF ETHNOPHARMACOLOGY 2015; 162:369-376. [PMID: 25614104 DOI: 10.1016/j.jep.2015.01.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 01/09/2015] [Accepted: 01/12/2015] [Indexed: 06/04/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE With the prevalent use of highly active antiretroviral therapy (HAART) for AIDS patients since 1996, the mortality of HIV/AIDS patients has been remarkably decreased. With long-term use of HAART, drug resistance and side effects of antiretrovirals have been frequently reported, which not only reduce the efficacy, but also decreases the tolerance of patients. Traditional herbal medicine has become more popular among HIV/AIDS patients as adjuvant therapy to reduce these adverse effects of HAART. SH formula is a Chinese herbal formula consisting of five traditional Chinese herbs including Morus alba L., Glycyrrhiza glabra L., Artemisia capillaris Thumb., Astragalus membranaceus Bge., and Carthamus tinctorius L. SH formula is clinically used for HIV treatment in Thailand. However, the possible pharmacokinetic interactions between these Chinese herbs and antiretroviral drugs have not been well documented. The aim of this study was to investigate the potential herb-drug interaction between SH herbal Chinese formula and the antiretroviral drug atazanavir (ATV). MATERIALS AND METHODS The combination effect of SH formula and ATV on HIV protease was studied in HIV-1 protease inhibition assay in vitro. The inhibition of SH formula on rat CYP3A2 was assessed by detecting the formation of 1'-OH midazolam from midazolam in rat liver microsomes in vitro. The in vivo pharmacokinetic interaction between SH formula and ATV was investigated by measuring time-dependent plasma concentrations of ATV in male Sprague-Dawley rats with liquid chromatography-mass spectrometry. RESULTS Through the in vitro HIV-1 protease inhibition assay, combination of SH formula (41.7-166.7 μg/ml) and ATV (16.7-33.3 ng/ml) showed additive inhibition on HIV-1 protease activity than SH formula or ATV used alone. In vitro incubation assay indicated that SH formula showed a weak inhibition (IC50=231.2 µg/ml; Ki=98.2 µg/ml) on CYP3A2 activity in rat liver microsomes. In vivo pharmacokinetic study demonstrated that SH formula did not affect the metabolism of ATV in rats. CONCLUSIONS Our study demonstrated for the first time that there is no metabolism-based herb-drug interaction between SH formula and ATV in rats, but this combination enhances the inhibition potentials against HIV protease activity. This observation may support the combinational use of anti-HIV treatment in human.
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Affiliation(s)
- Bao-Hui Cheng
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Xuelin Zhou
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Yan Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing 100050, China
| | - Judy Yuet-Wa Chan
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Huang-Quan Lin
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Penelope M Y Or
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - David Chi-Cheong Wan
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Ping-Chung Leung
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Kwok-Pui Fung
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China; School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Yi-Fen Wang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Clara Bik-San Lau
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China.
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Engineering a switch-on peptide to ricin A chain for increasing its specificity towards HIV-infected cells. Biochim Biophys Acta Gen Subj 2014; 1840:958-63. [DOI: 10.1016/j.bbagen.2013.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/22/2013] [Accepted: 11/07/2013] [Indexed: 12/11/2022]
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3
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Law SKY, Wang RR, Mak ANS, Wong KB, Zheng YT, Shaw PC. A switch-on mechanism to activate maize ribosome-inactivating protein for targeting HIV-infected cells. Nucleic Acids Res 2010; 38:6803-12. [PMID: 20558598 PMCID: PMC2965250 DOI: 10.1093/nar/gkq551] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Maize ribosome-inactivating protein (RIP) is a plant toxin that inactivates eukaryotic ribosomes by depurinating a specific adenine residue at the α-sarcin/ricin loop of 28S rRNA. Maize RIP is first produced as a proenzyme with a 25-amino acid internal inactivation region on the protein surface. During germination, proteolytic removal of this internal inactivation region generates the active heterodimeric maize RIP with full N-glycosidase activity. This naturally occurring switch-on mechanism provides an opportunity for targeting the cytotoxin to pathogen-infected cells. Here, we report the addition of HIV-1 protease recognition sequences to the internal inactivation region and the activation of the maize RIP variants by HIV-1 protease in vitro and in HIV-infected cells. Among the variants generated, two were cleaved efficiently by HIV-1 protease. The HIV-1 protease-activated variants showed enhanced N-glycosidase activity in vivo as compared to their un-activated counterparts. They also possessed potent inhibitory effect on p24 antigen production in human T cells infected by two HIV-1 strains. This switch-on strategy for activating the enzymatic activity of maize RIP in target cells provides a platform for combating pathogens with a specific protease.
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Affiliation(s)
- Sue Ka-Yee Law
- Department of Biochemistry and Centre for Protein Science and Crystallography, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
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4
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Sayer JM, Louis JM. Interactions of different inhibitors with active-site aspartyl residues of HIV-1 protease and possible relevance to pepsin. Proteins 2009; 75:556-68. [PMID: 18951411 DOI: 10.1002/prot.22271] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The importance of the active site region aspartyl residues 25 and 29 of the mature HIV-1 protease (PR) for the binding of five clinical and three experimental protease inhibitors [symmetric cyclic urea inhibitor DMP323, nonhydrolyzable substrate analog (RPB) and the generic aspartic protease inhibitor acetyl-pepstatin (Ac-PEP)] was assessed by differential scanning calorimetry. DeltaT(m) values, defined as the difference in T(m) for a given protein in the presence and absence of inhibitor, for PR with DRV, ATV, SQV, RTV, APV, DMP323, RPB, and Ac-PEP are 22.4, 20.8, 19.3, 15.6, 14.3, 14.7, 8.7, and 6.5 degrees C, respectively. Binding of APV and Ac-PEP is most sensitive to the D25N mutation, as shown by DeltaT(m) ratios [DeltaT(m)(PR)/DeltaT(m)(PR(D25N))] of 35.8 and 16.3, respectively, whereas binding of DMP323 and RPB (DeltaT(m) ratios of 1-2) is least affected. Binding of the substrate-like inhibitors RPB and Ac-PEP is nearly abolished (DeltaT(m)(PR)/DeltaT(m)(PR(D29N)) > or = 44) by the D29N mutation, whereas this mutation only moderately affects binding of the smaller inhibitors (DeltaT(m) ratios of 1.4-2.2). Of the nine FDA-approved clinical HIV-1 protease inhibitors screened, APV, RTV, and DRV competitively inhibit porcine pepsin with K(i) values of 0.3, 0.6, and 2.14 microM, respectively. DSC results were consistent with this relatively weak binding of APV (DeltaT(m) 2.7 degrees C) compared with the tight binding of Ac-PEP (DeltaT(m) > or = 17 degrees C). Comparison of superimposed structures of the PR/APV complex with those of PR/Ac-PEP and pepsin/pepstatin A complexes suggests a role for Asp215, Asp32, and Ser219 in pepsin, equivalent to Asp25, Asp25', and Asp29 in PR in the binding and stabilization of the pepsin/APV complex.
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Affiliation(s)
- Jane M Sayer
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, DHHS, Bethesda, MD 20892-0520, USA
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5
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Kogo H, Takeuchi K, Inoue H, Kihara H, Kojima M, Takahashi K. Urea-dependent unfolding of HIV-1 protease studied by circular dichroism and small-angle X-ray scattering. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:70-4. [DOI: 10.1016/j.bbapap.2008.09.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2008] [Revised: 09/20/2008] [Accepted: 09/28/2008] [Indexed: 11/28/2022]
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6
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LaFevre-Bernt M, Wu S, Lin X. Recombinant, refolded tetrameric p53 and gonadotropin-releasing hormone-p53 slow proliferation and induce apoptosis in p53-deficient cancer cells. Mol Cancer Ther 2008; 7:1420-9. [DOI: 10.1158/1535-7163.mct-08-0078] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The p53 tumor suppressor is mutated in over 50% of human cancers. Mutations resulting in amino acid changes within p53 result in a loss of activity and consequent changes in expression of genes that regulate DNA repair and cell cycle progression. Replacement of p53 using protein therapy would restore p53 function in p53-deficient tumor cells, with a consequence of tumor cell death and tumor regression. p53 functions in a tetrameric form in vivo. Here, we refolded a wild-type, full-length p53 from inclusion bodies expressed in Escherichia coli as a stable tetramer. The tetrameric p53 binds to p53-specific DNA and, when transformed into a p53-deficient cancer cell line, induced apoptosis of the transformed cells. Next, using the same expression and refolding technology, we produced a stable tetramer of recombinant gonadotropin-releasing hormone-p53 fusion protein (GnRH-p53), which traverses the plasma membrane, slows proliferation, and induces apoptosis in p53-deficient, GnRH-receptor–expressing cancer cell lines. In addition, we showed a time-dependent binding and internalization of GnRH-p53 to a receptor-expressing cell line. We conclude that the GnRH-p53 fusion strategy may provide a basis for constructing an effective cancer therapeutic for patients with tumors in GnRH-receptor–positive tissue types. [Mol Cancer Ther 2008;7(6):1420–9]
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Affiliation(s)
| | - Shili Wu
- 1ProteomTech, Inc., Costa Mesa, California and
| | - Xinli Lin
- 1ProteomTech, Inc., Costa Mesa, California and
- 2GeneCopoeia, Inc., Germantown, Maryland
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Hulko M, Lupas AN, Martin J. Inherent chaperone-like activity of aspartic proteases reveals a distant evolutionary relation to double-psi barrel domains of AAA-ATPases. Protein Sci 2007; 16:644-53. [PMID: 17384229 PMCID: PMC2203342 DOI: 10.1110/ps.062478607] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Chaperones and proteases share the ability to interact with unfolded proteins. Here we show that enzymatically inactive forms of the aspartic proteases HIV-1 protease and pepsin have inherent chaperone-like activity and can prevent the aggregation of denatured substrate proteins. In contrast to proteolysis, which requires dimeric enzymes, chaperone-like activity could be observed also with monomeric domains. The involvement of the active site cleft in the chaperone-like function was demonstrated by the inhibitory effect of peptide substrate inhibitors. The high structural similarity between aspartic proteases and the N-terminal double-psi barrels of Cdc48-like proteins, which are involved in the unfolding and dissociation of proteins, suggests that they share a common ancestor. The latent chaperone-like activity in aspartic proteases can be seen as a relic that has further evolved to serve substrate binding in the context of proteolytic activity.
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Affiliation(s)
- Michael Hulko
- Department of Protein Evolution, Max-Planck-Institute for Developmental Biology, D-72076 Tübingen, Germany
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8
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Chang WP, Downs D, Huang XP, Da H, Fung KM, Tang J. Amyloid‐beta reduction by memapsin 2 (beta‐secretase) immunization. FASEB J 2007; 21:3184-96. [PMID: 17494994 DOI: 10.1096/fj.06-7993com] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Memapsin 2 (beta-secretase, BACE1) is the protease that initiates cleavage of beta-amyloid precursor protein leading to the production of amyloid-beta (Abeta) and the onset of Alzheimer's disease (AD). Reducing Abeta by targeting memapsin 2 is a major strategy in developing new AD therapy. Here, in a proof-of-concept study, we show that immunization of transgenic AD mice (Tg2576) with memapsin 2 resulted in Abeta reduction and cognitive improvement. To study the basis of this therapy, we demonstrated that anti-memapsin 2 (anti-M2) antibodies were rapidly internalized and reduced Abeta production in cultured cells. These antibodies also effectively crossed the blood-brain barrier to reach the brain. Two- and 10-month Tg2576 mice were immunized and monitored over 10 and 6 months, respectively. We observed a significant decrease of plasma and brain Abeta40 and Abeta42 (approximately 35%) in the immunized mice as compared to controls. Immunized mice also showed better cognitive performance than controls in both cohorts. Brain histological analyses found no evidence of T cell/microglia/astrocyte activation in the immunized mice, suggesting the absence of inflammatory responses. These results suggest that memapsin 2 immunization in Tg2576 was effective in reducing Abeta production and improving cognitive function and that the current approach warrants further investigation as a therapy for AD.
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Affiliation(s)
- Wan-Pin Chang
- Protein Studies Program, Oklahoma Medical Research Foundation, 825 N.E. 13th St., Oklahoma City, OK 73104, USA.
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9
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Wittayanarakul K, Aruksakunwong O, Sompornpisut P, Sanghiran-Lee V, Parasuk V, Pinitglang S, Hannongbua S. Structure, dynamics and solvation of HIV-1 protease/saquinavir complex in aqueous solution and their contributions to drug resistance: molecular dynamic simulations. J Chem Inf Model 2006; 45:300-8. [PMID: 15807491 DOI: 10.1021/ci049784g] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As it is known that the understanding of the basic properties of the enzyme/inhibitor complex leads directly to enhancing the capability in drug designing and drug discovery. Molecular dynamics simulations have been performed to examine detailed information on the structure and dynamical properties of the HIV-1 PR complexed with saquinavir in the three protonated states, monoprotonates at Asp25 (Mono-25) and Asp25'(Mono-25') and diprotonate (Di-Pro) at both Asp25 and Asp25'. The obtained results support clinical data which reveal that Ile84 and Gly48 are two of the most frequent residues where mutation toward a protease inhibitor takes place. In contrast to the Ile84 mutation due to high displacement of Ile84 in the presence of saquinavir, source of the Gly48 mutation was observed to be due to the limited space in the HIV-1 PR pocket. The Gly48 was, on one side, found to form strong hydrogen bonds with saquinavir, while on the other side this residue was repelled by the hydrophobic Phe53 residue. In terms of inhibitor/enzyme binding, interactions between saquinavir and a catalytic triad of the HIV-1 PR were calculated using the ab initio method. The results show an order of the binding energy of Mono25<Di-pro<<Mono-25', suggesting that the active site in the HIV-1 PR complexed with saquinavir is monoprotonated states on Asp25. In contrast to the binding energy, 3, 6 and 12 hydrogen bonds between saquinavir and HIV-1 PR were found for the Mono-25, Mono-25' and Di-pro states, respectively. Discrepancy between the two trends suggests us to conclude that interaction between inhibitor and catalytic residues should be used as a criteria to enhance capability in drug designing and drug screening instead of using the total inhibitor/enzyme interaction which is normally reported in the literature. In addition, the distribution and binding of water molecules, in terms of hydrogen bonding, to the donor atoms of saquinavir were investigated and discussed, referring to that which was reported experimentally.
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Affiliation(s)
- Kitiyaporn Wittayanarakul
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Prathumwan, Bangkok 10330, Thailand
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Hou W, Medynski D, Wu S, Lin X, Li LY. VEGI-192, a new isoform of TNFSF15, specifically eliminates tumor vascular endothelial cells and suppresses tumor growth. Clin Cancer Res 2006; 11:5595-602. [PMID: 16061878 DOI: 10.1158/1078-0432.ccr-05-0384] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE We determined the antiangiogenic and anticancer activity of VEGI-192, a new isoform of TNFSF15 (VEGI, TL1), with a Lewis lung cancer murine tumor model. EXPERIMENTAL DESIGN Recombinant human VEGI-192 was produced in Escherichia coli and purified to apparent homogeneity. The protein was given systemically via i.p., i.v., or s.c. injections to tumor-bearing C57BL/6 mice. Tumor growth rates, animal survival rates, and general toxicity were determined. Effect on endothelial cell/smooth muscle cell ratio of the tumor vasculature was analyzed. RESULTS Systemic administration of VEGI-192 gave rise to a marked inhibition of tumor growth. As much as 50% inhibition of the tumor growth rate was achieved with treatment initiated when the tumor volumes reached nearly 5% of the body weight. Inhibition of tumor formation was also observed when VEGI-192 was given at the time of tumor inoculation. Consistently, we observed an increased survival time of the treated animals. The VEGI-192-treated animals showed no liver or kidney toxicity. The treatment eliminated tumor endothelial cells but not vascular smooth muscle cells, which remained associated with a residual vascular structure consisting of the basement membrane. In addition, we carried out immunohistochemical analysis of rat kidneys and found that vascular endothelial cell growth inhibitor (VEGI) expression is largely limited to endothelial cells. CONCLUSIONS Our findings indicate that VEGI is an endogenous inhibitor of angiogenesis, and that systemic administration of the VEGI-192 isoform resulted in inhibition of tumor angiogenesis and growth.
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Affiliation(s)
- Wen Hou
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213, USA
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Rajaiya J, Hatfield M, Nixon JC, Rawlings DJ, Webb CF. Bruton's tyrosine kinase regulates immunoglobulin promoter activation in association with the transcription factor Bright. Mol Cell Biol 2005; 25:2073-84. [PMID: 15743806 PMCID: PMC1061591 DOI: 10.1128/mcb.25.6.2073-2084.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Revised: 07/06/2004] [Accepted: 12/13/2004] [Indexed: 01/19/2023] Open
Abstract
Bright (B-cell regulator of immunoglobulin heavy chain transcription) binding to immunoglobulin heavy chain loci after B-cell activation is associated with increased heavy chain transcription. Our earlier reports demonstrated that Bright coimmunoprecipitates with Bruton's tyrosine kinase (Btk) and that these proteins associate in a DNA-binding complex in primary B cells. B cells from immunodeficient mice with a mutation in Btk failed to produce stable Bright DNA-binding complexes. In order to determine if Btk is important for Bright function, a transcription activation assay was established and analyzed using real-time PCR technology. Cells lacking both Bright and Btk were transfected with Bright and/or Btk along with an immunoglobulin heavy chain reporter construct. Immunoglobulin gene transcription was enhanced when Bright and Btk were coexpressed. In contrast, neither Bright nor Btk alone led to activation of heavy chain transcription. Furthermore, Bright function required both Btk kinase activity and sequences within the pleckstrin homology domain of Btk. Bright was not appreciably phosphorylated by Btk; however, a third tyrosine-phosphorylated protein coprecipitated with Bright. Thus, the ability of Bright to enhance immunoglobulin transcription critically requires functional Btk.
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Affiliation(s)
- Jaya Rajaiya
- Oklahoma Medical Research Foundation, Immunobiology and Cancer Research Program, 825 N.E. 13th St., Oklahoma City, OK 73104, USA
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Zhu G, Zhai P, Wakeham N, He X, Zhang XC. Analysis of the Interaction between GGA1 GAT Domain and Rabaptin‐5. Methods Enzymol 2005; 403:583-92. [PMID: 16473621 DOI: 10.1016/s0076-6879(05)03050-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
GGAs are a family of adaptor proteins involved in vesicular transport. As an effector of the small GTPase Arf, GGA interacts using its GAT domain with the GTP-bound form of Arf. The GAT domain is also found to interact with ubiquitin and rabaptin-5. Rabaptin-5 is, in turn, an effector of another small GTPase, Rab5, which regulates early endosome fusion. The interaction between GGAs and rabaptin-5 is likely to take place in a pathway between the trans-Golgi network and early endosomes. This chapter describes in vitro biochemical characterization of the interaction between the GGA1 GAT domain and rabaptin-5. Combining with the complex crystal structure, we reveal that the binding mode is helix bundle-to-helix bundle in nature.
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Abstract
Recent studies have used cross-species comparisons of expression profiles to annotate gene functions, to draw evolutionary inferences concerning specific biological processes and to study the global properties of expression networks. The rapid accumulation of microarray data from multiple species provides unprecedented opportunities to study the evolution of biological systems. Recent studies have used cross-species comparisons of expression profiles to annotate gene functions, to draw evolutionary inferences concerning specific biological processes and to study the global properties of expression networks.
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Affiliation(s)
- Xianghong Jasmine Zhou
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0371, USA
| | - Greg Gibson
- Department of Genetics, North Carolina State University, Raleigh, NC 27695-7614, USA
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14
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Kopcho LM, Ma J, Marcinkeviciene J, Lai Z, Witmer MR, Cheng J, Yanchunas J, Tredup J, Corbett M, Calambur D, Wittekind M, Paruchuri M, Kothari D, Lee G, Ganguly S, Ramamurthy V, Morin PE, Camac DM, King RW, Lasut AL, Ross OH, Hillman MC, Fish B, Shen K, Dowling RL, Kim YB, Graciani NR, Collins D, Combs AP, George H, Thompson LA, Copeland RA. Comparative studies of active site-ligand interactions among various recombinant constructs of human beta-amyloid precursor protein cleaving enzyme. Arch Biochem Biophys 2003; 410:307-16. [PMID: 12573291 DOI: 10.1016/s0003-9861(02)00690-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Amyloid precursor protein (APP) cleaving enzyme (BACE) is the enzyme responsible for beta-site cleavage of APP, leading to the formation of the amyloid-beta peptide that is thought to be pathogenic in Alzheimer's disease (AD). Hence, BACE is an attractive pharmacological target, and numerous research groups have begun searching for potent and selective inhibitors of this enzyme as a potential mechanism for therapeutic intervention in AD. The mature enzyme is composed of a globular catalytic domain that is N-linked glycosylated in mammalian cells, a single transmembrane helix that anchors the enzyme to an intracellular membrane, and a short C-terminal domain that extends outside the phospholipid bilayer of the membrane. Here we have compared the substrate and active site-directed inhibitor binding properties of several recombinant constructs of human BACE. The constructs studied here address the importance of catalytic domain glycosylation state, inclusion of domains other than the catalytic domain, and incorporation into a membrane bilayer on the interactions of the enzyme active site with peptidic ligands. We find no significant differences in ligand binding properties among these various constructs. These data demonstrate that the nonglycosylated, soluble catalytic domain of BACE faithfully reflects the ligand binding properties of the full-length mature enzyme in its natural membrane environment. Thus, the use of the nonglycosylated, soluble catalytic domain of BACE is appropriate for studies aimed at understanding the determinants of ligand recognition by the enzyme active site.
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Affiliation(s)
- Lisa M Kopcho
- Department of Chemical Enzymology, Hopewell, NJ, USA
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15
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Affiliation(s)
- Liang Tong
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
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Kim YT, Downs D, Wu S, Dashti A, Pan Y, Zhai P, Wang X, Zhang XC, Lin X. Enzymic properties of recombinant BACE2. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:5668-77. [PMID: 12423367 DOI: 10.1046/j.1432-1033.2002.03277.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACE2 (Memapsin 1) is a membrane-bound aspartic protease that is highly homologous with BACE1 (Memapsin 2). While BACE1 processes the amyloid precursor protein (APP) at a key step in generating the beta-amyloid peptide and presumably causes Alzheimer's disease (AD), BACE2 has not been demonstrated to be directly involved in APP processing, and its physiological functions remain to be determined. In vivo, BACE2 is expressed as a precursor protein containing pre-, pro-, protease, transmembrane, and cytosolic domains/peptides. To determine the enzymatic properties of BACE2, two variants of its pro-protease domain, pro-BACE2-T1 (PB2-T1) and pro-BACE2-T2 (PB2-T2), were constructed. They have been expressed in Escherichia coli as inclusion bodies, refolded and purified. These two recombinant proteins have the same N terminus but differ at their C-terminal ends: PB2-T1 ends at Pro466, on the boundary of the postulated transmembrane domain, and PB2-T2 ends at Ser431, close to the homologous ends of other aspartic proteases such as pepsin. While PB2-T1 shares similar substrate specificities with BACE1 and other 'general' aspartic proteases, the specificity of PB2-T2 is more constrained, apparently preferring to cleave at the NH2-terminal side of paired basic residues. Unlike other 'typical' aspartic proteases, which are active only under acidic conditions, the recombinant BACE2, PB2-T1, was active at a broad pH range. In addition, pro-BACE2 can be processed at its in vivo maturation site by BACE1.
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Affiliation(s)
- Yong-Tae Kim
- Functional Proteomics Laboratory and Crystallography Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Babé LM, Linnevers CJ, Schmidt BF. Production of active mammalian and viral proteases in bacterial expression systems. Biotechnol Genet Eng Rev 2001; 17:213-52. [PMID: 11255667 DOI: 10.1080/02648725.2000.10647993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- L M Babé
- Axys Pharmaceuticals Inc., 180 Kimball Way, South San Francisco, CA 94080, USA.
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18
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Hong L, Koelsch G, Lin X, Wu S, Terzyan S, Ghosh AK, Zhang XC, Tang J. Structure of the protease domain of memapsin 2 (beta-secretase) complexed with inhibitor. Science 2000; 290:150-3. [PMID: 11021803 DOI: 10.1126/science.290.5489.150] [Citation(s) in RCA: 536] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Memapsin 2 (beta-secretase) is a membrane-associated aspartic protease involved in the production of beta-amyloid peptide in Alzheimer's disease and is a major target for drug design. We determined the crystal structure of the protease domain of human memapsin 2 complexed to an eight-residue inhibitor at 1.9 angstrom resolution. The active site of memapsin 2 is more open and less hydrophobic than that of other human aspartic proteases. The subsite locations from S4 to S2' are well defined. A kink of the inhibitor chain at P2' and the change of chain direction of P3' and P4' may be mimicked to provide inhibitor selectivity.
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Affiliation(s)
- L Hong
- Protein Studies Program and Crystallography Program, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA
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19
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Galea CA, Dalrymple BP, Kuypers R, Blakeley R. Modification of the substrate specificity of porcine pepsin for the enzymatic production of bovine hide gelatin. Protein Sci 2000; 9:1947-59. [PMID: 11106168 PMCID: PMC2144476 DOI: 10.1110/ps.9.10.1947] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The substrate specificity of porcine pepsin has been altered by site-directed mutagenesis in an attempt to selectively cleave bovine hide collagen at only a few sites, similar to cathepsin D, for the production of high quality gelatin. Kinetic parameters were determined using chromogenic peptide substrates based on the sequence Lys-Pro-Xaa-Yaa-Phe*Nph-Arg-Leu (where Xaa is Ile or Pro, Yaa is Glu. Leu, Gln or Lys, Nph is p-nitrophenylalanine, and * is the site of cleavage). Substitution of Thr222 and Glu287 within the S2 subsite of pepsin by Val and Met, respectively, produced a double mutant with a two- to fourfold higher kcat/Km, compared with wild-type pepsin, for the chromogenic peptides with residues Leu, Gln, and Glu at position P2 (Yaa). The results suggest that the functional group of the P2 side chain may be exposed to solvent, while the aliphatic portion interacts with hydrophobic residues comprising S2. Wild-type pepsin cleaved a peptide corresponding to the carboxy-terminal telopeptide region of bovine type I collagen alpha1 chain, SGGYDLSFLPQPPQE, predominantly at three sites (Asp-Leu, Leu-Ser, and Phe-Leu) and at a significantly lower rate at Ser-Phe. However, Thr222Val/Glu287Met cleaved site Ser-Phe at a rate 20-fold higher than the wild-type. Significantly, enzymes containing the double substitution Phe111Thr/Leu112Phe cleaved this peptide predominantly at one site Leu-Ser (similar to cathepsin D) and at a rate 23-fold higher than the wild-type. These mutants can potentially enhance the rate of solubilization of bovine hide collagen under conditions mild enough to maintain the triple helix structure and hence minimize the rate of subsequent denaturation and proteolytic cleavage.
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Affiliation(s)
- C A Galea
- Department of Biochemistry, University of Queensland, St. Lucia, Australia
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20
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Bennett BD, Babu-Khan S, Loeloff R, Louis JC, Curran E, Citron M, Vassar R. Expression analysis of BACE2 in brain and peripheral tissues. J Biol Chem 2000; 275:20647-51. [PMID: 10749877 DOI: 10.1074/jbc.m002688200] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Beta-site amyloid precursor protein cleaving enzyme (BACE) is a novel transmembrane aspartic protease that possesses all the known characteristics of the beta-secretase involved in Alzheimer's disease (Vassar, R., Bennett, B. D., Babu-Khan, S., Kahn, S., Mendiaz, E. A., Denis, P., Teplow, D. B., Ross, S., Amarante, P., Loeloff, R., Luo, Y., Fisher, S., Fuller, J., Edenson, S., Lile, J., Jarosinski, M. A., Biere, A. L., Curran, E., Burgess, T., Louis, J. -C., Collins, F., Treanor, J., Rogers, G., and Citron, M. (1999) Science 286, 735-741). We have analyzed the sequence and expression pattern of a BACE homolog termed BACE2. BACE and BACE2 are unique among aspartic proteases in that they possess a carboxyl-terminal extension with a predicted transmembrane region and together they define a new family. Northern analysis reveals that BACE2 mRNA is expressed at low levels in most human peripheral tissues and at higher levels in colon, kidney, pancreas, placenta, prostate, stomach, and trachea. Human adult and fetal whole brain and most adult brain subregions express very low or undetectable levels of BACE2 mRNA. In addition, in situ hybridization of adult rat brain shows that BACE2 mRNA is expressed at very low levels in most brain regions. The very low or undetectable levels of BACE2 mRNA in the brain are not consistent with the expression pattern predicted for beta-secretase.
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Affiliation(s)
- B D Bennett
- Amgen, Inc., Thousand Oaks, California 91320-1799, USA
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21
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Au TK, Collins RA, Lam TL, Ng TB, Fong WP, Wan DC. The plant ribosome inactivating proteins luffin and saporin are potent inhibitors of HIV-1 integrase. FEBS Lett 2000; 471:169-72. [PMID: 10767416 DOI: 10.1016/s0014-5793(00)01389-2] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The ribosome inactivating proteins (RIPs) are a group of proteins that are able to inactivate eukaryotic protein synthesis by attacking the 28S ribosomal RNA. Recent studies have shown that some RIPs possess strong anti-human immunodeficiency virus (HIV) activity. In this study, several common plant RIPs including agrostin, gelonin, luffin, alpha-momorcharin, beta-momorcharin, saporin and trichosanthin were examined for the ability to interfere with HIV-1 replication in a variety of mechanistic assays in vitro. These assays included the CD4/gp120 interaction assay, HIV-1 reverse transcriptase (RT) assay, HIV-1 protease assay and HIV-1 integrase assay. At the concentration of 100 nM, all RIPs appeared to enhance the CD4/gp120 interaction by about 50%. These RIPs exhibited a very weak suppressive effect on HIV-1 RT and on HIV-1 protease. In contrast, with the exception of agrostin, all the RIPs tested could strongly inhibit HIV-1 integrase, the extent of inhibition ranging from 26.1 to 96.3% in an ELISA-based assay. Two RIPs, saporin and luffin, which licited over 90% inhibition in the ELISA-based assay, were further characterized in a radiometric assay. Both of these two RIPs evoked a strong dose-dependent inhibition in the 3'-end processing and strand-transfer activities of integrase. The results from this study suggest that the anti-HIV property of RIPs may be due to inhibition of HIV-1 integrase.
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Affiliation(s)
- T K Au
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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22
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Lin X, Koelsch G, Wu S, Downs D, Dashti A, Tang J. Human aspartic protease memapsin 2 cleaves the beta-secretase site of beta-amyloid precursor protein. Proc Natl Acad Sci U S A 2000; 97:1456-60. [PMID: 10677483 PMCID: PMC26455 DOI: 10.1073/pnas.97.4.1456] [Citation(s) in RCA: 638] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/1999] [Accepted: 12/14/1999] [Indexed: 11/18/2022] Open
Abstract
The cDNAs of two new human membrane-associated aspartic proteases, memapsin 1 and memapsin 2, have been cloned and sequenced. The deduced amino acid sequences show that each contains the typical pre, pro, and aspartic protease regions, but each also has a C-terminal extension of over 80 residues, which includes a single transmembrane domain and a C-terminal cytosolic domain. Memapsin 2 mRNA is abundant in human brain. The protease domain of memapsin 2 cDNA was expressed in Escherichia coli and was purified. Recombinant memapsin 2 specifically hydrolyzed peptides derived from the beta-secretase site of both the wild-type and Swedish mutant beta-amyloid precursor protein (APP) with over 60-fold increase of catalytic efficiency for the latter. Expression of APP and memapsin 2 in HeLa cells showed that memapsin 2 cleaved the beta-secretase site of APP intracellularly. These and other results suggest that memapsin 2 fits all of the criteria of beta-secretase, which catalyzes the rate-limiting step of the in vivo production of the beta-amyloid (Abeta) peptide leading to the progression of Alzheimer's disease. Recombinant memapsin 2 also cleaved a peptide derived from the processing site of presenilin 1, albeit with poor kinetic efficiency. Alignment of cleavage site sequences of peptides indicates that the specificity of memapsin 2 resides mainly at the S(1)' subsite, which prefers small side chains such as Ala, Ser, and Asp.
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Affiliation(s)
- X Lin
- Protein Studies Program, Oklahoma Medical Research Foundation, and Department of Biochemistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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23
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Wang X, Terzyan S, Tang J, Loy JA, Lin X, Zhang XC. Human plasminogen catalytic domain undergoes an unusual conformational change upon activation. J Mol Biol 2000; 295:903-14. [PMID: 10656799 DOI: 10.1006/jmbi.1999.3397] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of the serine protease plasmin from its zymogen, plasminogen, is the key step in fibrinolysis leading to blood clot dissolution. It also plays critical roles in cell migration, such as in tumor metastasis. Here, we report the crystal structure of an inactive S741A mutant of human plasminogen catalytic domain at 2.0 A resolution. This structure permits a direct comparison with that of the plasmin catalytic unit. Unique conformational differences are present between these two structures that are not seen in other zymogen-enzyme pairs of the trypsin family. The functional significance of these differences and the structural basis of plasminogen activation is discussed in the light of this new structure.
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Affiliation(s)
- X Wang
- Oklahoma Medical Research Foundation, Crystallography Program, 825 N. E. 13(th) Street, Oklahoma City, OK, 73104, USA
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24
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Abstract
Streptokinase, a 47 kDa secreted protein of hemolytic strains of streptococci, is a human plasminogen activator and contains three structural domains linked by flexible loops. We describe here the crystal structure of the isolated streptokinase middle (SKbeta) domain determined at 2.4 A resolution. Among the functionally important structural features is a putative binding site for a kringle domain of plasminogen located at the tip of a fully exposed hairpin loop. The distribution of genetically conserved residues of SKbeta is strongly correlated with their functions. The extensive interface of the SKbeta dimer suggests that such dimers may also exist in solution for free SKbeta.
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Affiliation(s)
- X Wang
- Crystallography Program, Oklahoma Medical Research Foundation, 825 N. E. 13th Street, Oklahoma City, OK 73104, USA
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25
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Melnick L, Yang SS, Rossi R, Zepp C, Heefner D. An Escherichia coli expression assay and screen for human immunodeficiency virus protease variants with decreased susceptibility to indinavir. Antimicrob Agents Chemother 1998; 42:3256-65. [PMID: 9835523 PMCID: PMC106031 DOI: 10.1128/aac.42.12.3256] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/1998] [Accepted: 09/12/1998] [Indexed: 11/20/2022] Open
Abstract
We have developed a recombinant Escherichia coli screening system for the rapid detection and identification of amino acid substitutions in the human immunodeficiency virus (HIV) protease associated with decreased susceptibility to the protease inhibitor indinavir (MK-639; Merck & Co.). The assay depends upon the correct processing of a segment of the HIV-1 HXB2 gag-pol polyprotein followed by detection of HIV reverse transcriptase activity by a highly sensitive, colorimetric enzyme-linked immunosorbent assay. The highly sensitive system detects the contributions of single substitutions such as I84V, L90M, and L63P. The combination of single substitutions further decreases the sensitivity to indinavir. We constructed a library of HIV protease variant genes containing dispersed mutations and, using the E. coli recombinant system, screened for mutants with decreased indinavir sensitivity. The discovered HIV protease variants contain amino acid substitutions commonly associated with indinavir resistance in clinical isolates, including the substitutions L90M, L63P, I64V, V82A, L24I, and I54T. One substitution, W6R, is also frequently found by the screen and has not been reported elsewhere. Of a total of 12,000 isolates that were screened, 12 protease variants with decreased sensitivity to indinavir were found. The L63P substitution, which is also associated with indinavir resistance, increases the stability of the isolated protease relative to that of the native HXB2 protease. The rapidity, sensitivity, and accuracy of this screen also make it useful for screening for novel inhibitors. We have found the approach described here to be useful for the detection of amino acid substitutions in HIV protease that have been associated with drug resistance as well as for the screening of novel compounds for inhibitory activity.
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Affiliation(s)
- L Melnick
- Sepracor Inc., Marlborough, Massachusetts 01752, USA.
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26
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Wang X, Lin X, Loy JA, Tang J, Zhang XC. Crystal structure of the catalytic domain of human plasmin complexed with streptokinase. Science 1998; 281:1662-5. [PMID: 9733510 DOI: 10.1126/science.281.5383.1662] [Citation(s) in RCA: 171] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Streptokinase is a plasminogen activator widely used in treating blood-clotting disorders. Complexes of streptokinase with human plasminogen can hydrolytically activate other plasminogen molecules to plasmin, which then dissolves blood clots. A similar binding activation mechanism also occurs in some key steps of blood coagulation. The crystal structure of streptokinase complexed with the catalytic unit of human plasmin was solved at 2.9 angstroms. The amino-terminal domain of streptokinase in the complex is hypothesized to enhance the substrate recognition. The carboxyl-terminal domain of streptokinase, which binds near the activation loop of plasminogen, is likely responsible for the contact activation of plasminogen in the complex.
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Affiliation(s)
- X Wang
- Crystallography Program, Oklahoma Medical Research Foundation, 825 N.E. 13th Street, Oklahoma City, OK 73104, USA
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27
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Affiliation(s)
- B Goldberg
- DNCB Study Group, California Pacific Medical Center, San Francisco, USA
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