1
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Detomasi TC, Batka AE, Valastyan JS, Hydorn MA, Craik CS, Bassler BL, Marletta MA. Proteases influence colony aggregation behavior in Vibrio cholerae. J Biol Chem 2023; 299:105386. [PMID: 37898401 PMCID: PMC10709122 DOI: 10.1016/j.jbc.2023.105386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 10/03/2023] [Accepted: 10/16/2023] [Indexed: 10/30/2023] Open
Abstract
Aggregation behavior provides bacteria protection from harsh environments and threats to survival. Two uncharacterized proteases, LapX and Lap, are important for Vibrio cholerae liquid-based aggregation. Here, we determined that LapX is a serine protease with a preference for cleavage after glutamate and glutamine residues in the P1 position, which processes a physiologically based peptide substrate with a catalytic efficiency of 180 ± 80 M-1s-1. The activity with a LapX substrate identified by a multiplex substrate profiling by mass spectrometry screen was 590 ± 20 M-1s-1. Lap shares high sequence identity with an aminopeptidase (termed VpAP) from Vibrio proteolyticus and contains an inhibitory bacterial prepeptidase C-terminal domain that, when eliminated, increases catalytic efficiency on leucine p-nitroanilide nearly four-fold from 5.4 ± 4.1 × 104 M-1s-1 to 20.3 ± 4.3 × 104 M-1s-1. We demonstrate that LapX processes Lap to its mature form and thus amplifies Lap activity. The increase is approximately eighteen-fold for full-length Lap (95.7 ± 5.6 × 104 M-1s-1) and six-fold for Lap lacking the prepeptidase C-terminal domain (11.3 ± 1.9 × 105 M-1s-1). In addition, substrate profiling reveals preferences for these two proteases that could inform in vivo function. Furthermore, purified LapX and Lap restore the timing of the V. cholerae aggregation program to a mutant lacking the lapX and lap genes. Both proteases must be present to restore WT timing, and thus they appear to act sequentially: LapX acts on Lap, and Lap acts on the substrate involved in aggregation.
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Affiliation(s)
- Tyler C Detomasi
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA; Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
| | - Allison E Batka
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA
| | - Julie S Valastyan
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; The Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Molly A Hydorn
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA; Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Charles S Craik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
| | - Bonnie L Bassler
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; The Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Michael A Marletta
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, California, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA.
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2
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Bandyopadhyay D, Murthy MRN, Balaram H, Balaram P. Probing the role of highly conserved residues in triosephosphate isomerase - analysis of site specific mutants at positions 64 and 75 in thePlasmodialenzyme. FEBS J 2015. [DOI: 10.1111/febs.13384] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | | | - Hemalatha Balaram
- Molecular Biology and Genetics Unit; Jawaharlal Nehru Centre for Advanced Scientific Research; Bangalore India
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3
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Gable J, Acker TM, Craik CS. Current and potential treatments for ubiquitous but neglected herpesvirus infections. Chem Rev 2014; 114:11382-412. [PMID: 25275644 PMCID: PMC4254030 DOI: 10.1021/cr500255e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Indexed: 02/07/2023]
Affiliation(s)
- Jonathan
E. Gable
- Department
of Pharmaceutical Chemistry, University
of California, San Francisco, 600 16th Street, San Francisco, California 94158-2280, United States
- Graduate
Group in Biophysics, University of California,
San Francisco, 600 16th
Street, San Francisco, California 94158-2280, United States
| | - Timothy M. Acker
- Department
of Pharmaceutical Chemistry, University
of California, San Francisco, 600 16th Street, San Francisco, California 94158-2280, United States
| | - Charles S. Craik
- Department
of Pharmaceutical Chemistry, University
of California, San Francisco, 600 16th Street, San Francisco, California 94158-2280, United States
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4
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Gable JE, Lee GM, Jaishankar P, Hearn BR, Waddling CA, Renslo AR, Craik CS. Broad-spectrum allosteric inhibition of herpesvirus proteases. Biochemistry 2014; 53:4648-60. [PMID: 24977643 PMCID: PMC4108181 DOI: 10.1021/bi5003234] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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Herpesviruses
rely on a homodimeric protease for viral capsid maturation.
A small molecule, DD2, previously shown to disrupt dimerization of
Kaposi’s sarcoma-associated herpesvirus protease (KSHV Pr)
by trapping an inactive monomeric conformation and two analogues generated
through carboxylate bioisosteric replacement (compounds 2 and 3) were shown to inhibit the associated proteases
of all three human herpesvirus (HHV) subfamilies (α, β,
and γ). Inhibition data reveal that compound 2 has
potency comparable to or better than that of DD2 against the tested
proteases. Nuclear magnetic resonance spectroscopy and a new application
of the kinetic analysis developed by Zhang and Poorman [Zhang, Z.
Y., Poorman, R. A., et al. (1991) J. Biol. Chem. 266, 15591–15594] show DD2, compound 2, and compound 3 inhibit HHV proteases by dimer disruption. All three compounds
bind the dimer interface of other HHV proteases in a manner analogous
to binding of DD2 to KSHV protease. The determination and analysis
of cocrystal structures of both analogues with the KSHV Pr monomer
verify and elaborate on the mode of binding for this chemical scaffold,
explaining a newly observed critical structure–activity relationship.
These results reveal a prototypical chemical scaffold for broad-spectrum
allosteric inhibition of human herpesvirus proteases and an approach
for the identification of small molecules that allosterically regulate
protein activity by targeting protein–protein interactions.
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Affiliation(s)
- Jonathan E Gable
- Department of Pharmaceutical Chemistry, University of California , San Francisco, California 94158-2280, United States
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5
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Craik CS, Shahian T. A screening strategy for trapping the inactive conformer of a dimeric enzyme with a small molecule inhibitor. Methods Mol Biol 2012; 928:119-131. [PMID: 22956137 PMCID: PMC3739972 DOI: 10.1007/978-1-62703-008-3_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi's sarcoma (KS), the most common cancer in AIDS patients. All herpesviruses express a conserved dimeric serine protease that is required for generating infectious virions and is therefore of pharmaceutical interest. Given the past challenges of developing drug-like active-site inhibitors to this class of proteases, small-molecules targeting allosteric sites are of great value. In light of evidence supporting a strong structural linkage between the dimer interface and the protease active site, we have focused our efforts on the dimer interface for identifying dimer disrupting inhibitors. Here, we describe a high throughput screening approach for identifying small molecule dimerization inhibitors of KSHV protease. The helical mimetic, small molecule library used, as well as general strategies for selecting compound libraries for this application will also be discussed. This methodology can be applicable to other systems where an alpha helical moiety plays a dominant role at the interaction site of interest, and in vitro assays to monitor function are in place.
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Affiliation(s)
- Charles S Craik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
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6
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Lee GM, Shahian T, Baharuddin A, Gable JE, Craik CS. Enzyme inhibition by allosteric capture of an inactive conformation. J Mol Biol 2011; 411:999-1016. [PMID: 21723875 DOI: 10.1016/j.jmb.2011.06.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 06/15/2011] [Accepted: 06/16/2011] [Indexed: 10/18/2022]
Abstract
All members of the human herpesvirus protease (HHV Pr) family are active as weakly associating dimers but inactive as monomers. A small-molecule allosteric inhibitor of Kaposi's sarcoma-associated herpesvirus protease (KSHV Pr) traps the enzyme in an inactive monomeric state where the C-terminal helices are unfolded and the hydrophobic dimer interface is exposed. NMR titration studies demonstrate that the inhibitor binds to KSHV Pr monomers with low micromolar affinity. A 2.0-Å-resolution X-ray crystal structure of a C-terminal truncated KSHV Pr-inhibitor complex locates the binding pocket at the dimer interface and displays significant conformational perturbations at the active site, 15 Å from the allosteric site. NMR and CD data suggest that the small molecule inhibits human cytomegalovirus protease via a similar mechanism. As all HHV Prs are functionally and structurally homologous, the inhibitor represents a class of compounds that may be developed into broad-spectrum therapeutics that allosterically regulate enzymatic activity by disrupting protein-protein interactions.
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Affiliation(s)
- Gregory M Lee
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158-2280, USA
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7
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Shemetov AA, Seit-Nebi AS, Gusev NB. Phosphorylation of human small heat shock protein HspB8 (Hsp22) by ERK1 protein kinase. Mol Cell Biochem 2011; 355:47-55. [DOI: 10.1007/s11010-011-0837-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 04/15/2011] [Indexed: 11/25/2022]
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8
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Shen A. Allosteric regulation of protease activity by small molecules. MOLECULAR BIOSYSTEMS 2010; 6:1431-43. [PMID: 20539873 DOI: 10.1039/c003913f] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Proteases regulate a plethora of biological processes. Because they irreversibly cleave peptide bonds, the activity of proteases is strictly controlled. While there are many ways to regulate protease activity, an emergent mechanism is the modulation of protease function by small molecules acting at allosteric sites. This mode of regulation holds the potential to allow for the specific and temporal control of a given biological process using small molecules. These compounds also serve as useful tools for studying protein dynamics and function. This review highlights recent advances in identifying and characterizing natural and synthetic small molecule allosteric regulators of proteases and discusses their utility in studies of protease function, drug discovery and protein engineering.
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Affiliation(s)
- Aimee Shen
- Department of Pathology, Stanford School of Medicine, Stanford, California 94305, USA.
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9
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Shahian T, Lee GM, Lazic A, Arnold LA, Velusamy P, Roels CM, Guy RK, Craik CS. Inhibition of a viral enzyme by a small-molecule dimer disruptor. Nat Chem Biol 2009; 5:640-6. [PMID: 19633659 PMCID: PMC2752665 DOI: 10.1038/nchembio.192] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 05/18/2009] [Indexed: 11/03/2022]
Abstract
Small molecule dimer disruptors that inhibit an essential dimeric protease of human Kaposi’s sarcoma-associated herpesvirus (KSHV) were identified by screening an α-helical mimetic library. Subsequently, a second generation of low micromolar inhibitors with improved potency and solubility was synthesized. Complementary methods including size exclusion chromatography and 1H-13C HSQC titration using selectively labeled 13C-Met samples revealed that monomeric protease is enriched in the presence of inhibitor. 1H-15N-HSQC titration studies mapped the inhibitor binding-site to the dimer interface, and mutagenesis studies targeting this region were consistent with a mechanism where inhibitor binding prevents dimerization through the conformational selection of a dynamic intermediate. These results validate the interface of herpesvirus proteases and other similar oligomeric interactions as suitable targets for the development of small molecule inhibitors.
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Affiliation(s)
- Tina Shahian
- Graduate Group in Biochemistry and Molecular Biology, University of California, San Francisco, California, USA
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10
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Small capsid protein pORF65 is essential for assembly of Kaposi's sarcoma-associated herpesvirus capsids. J Virol 2008; 82:7201-11. [PMID: 18463150 DOI: 10.1128/jvi.00423-08] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent for KS tumors, multicentric Castleman's disease, and primary effusion lymphomas. Like other herpesvirus capsids, the KSHV capsid is an icosahedral structure composed of six proteins. The capsid shell is made up of the major capsid protein, two triplex proteins, and the small capsid protein. The scaffold protein and the protease occupy the internal space. The assembly of KSHV capsids is thought to occur in a manner similar to that determined for herpes simplex virus type 1 (HSV-1). Our goal was to assemble KSHV capsids in insect cells using the baculovirus expression vector system. Six KSHV capsid open reading frames were cloned and the proteins expressed in Sf9 cells: pORF25 (major capsid protein), pORF62 (triplex 1), pORF26 (triplex 2), pORF17 (protease), pORF17.5 (scaffold protein), and also pORF65 (small capsid protein). When insect cells were coinfected with these baculoviruses, angular capsids that contained internal core structures were readily observed by conventional electron microscopy of the infected cells. Capsids were also readily isolated from infected cells by using rate velocity sedimentation. With immuno-electron microscopy methods, these capsids were seen to be reactive to antisera to pORF65 as well as to KSHV-positive human sera, indicating the correct conformation of pORF65 in these capsids. When either virus expressing the triplex proteins was omitted from the coinfection, capsids did not assemble; similar to observations made in HSV-1-infected cells. If the virus expressing the scaffold protein was excluded, large open shells that did not attain icosahedral structure were seen in the nuclei of infected cells. The presence of pORF65 was required for capsid assembly, in that capsids did not form if this protein was absent as judged by both by ultrastructural analysis of infected cells and rate velocity sedimentation experiments. Thus, a novel outcome of this study is the finding that the small capsid protein of KSHV, like the major capsid and triplex proteins, is essential for capsid shell assembly.
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11
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Lazic A, Goetz DH, Nomura AM, Marnett AB, Craik CS. Substrate modulation of enzyme activity in the herpesvirus protease family. J Mol Biol 2007; 373:913-23. [PMID: 17870089 PMCID: PMC2078331 DOI: 10.1016/j.jmb.2007.07.073] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Revised: 07/21/2007] [Accepted: 07/26/2007] [Indexed: 11/23/2022]
Abstract
The herpesvirus proteases are an example in which allosteric regulation of an enzyme activity is achieved through the formation of quaternary structure. Here, we report a 1.7 A resolution structure of Kaposi's sarcoma-associated herpesvirus protease in complex with a hexapeptide transition state analogue that stabilizes the dimeric state of the enzyme. Extended substrate binding sites are induced upon peptide binding. In particular, 104 A2 of surface are buried in the newly formed S4 pocket when tyrosine binds at this site. The peptide inhibitor also induces a rearrangement of residues that stabilizes the oxyanion hole and the dimer interface. Concomitant with the structural changes, an increase in catalytic efficiency of the enzyme results upon extended substrate binding. A nearly 20-fold increase in kcat/KM results upon extending the peptide substrate from a tetrapeptide to a hexapeptide exclusively due to a KM effect. This suggests that the mechanism by which herpesvirus proteases achieve their high specificity is by using extended substrates to modulate both the structure and activity of the enzyme.
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Affiliation(s)
- Ana Lazic
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158-2517, USA
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12
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Brignole EJ, Gibson W. Enzymatic activities of human cytomegalovirus maturational protease assemblin and its precursor (pPR, pUL80a) are comparable: [corrected] maximal activity of pPR requires self-interaction through its scaffolding domain. J Virol 2007; 81:4091-103. [PMID: 17287260 PMCID: PMC1866128 DOI: 10.1128/jvi.02821-06] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Herpesviruses encode an essential, maturational serine protease whose catalytic domain, assemblin (28 kDa), is released by self-cleavage from a 74-kDa precursor (pPR, pUL80a). Although there is considerable information about the structure and enzymatic characteristics of assemblin, a potential pharmacologic target, comparatively little is known about these features of the precursor. To begin studying pPR, we introduced five point mutations that stabilize it against self-cleavage at its internal (I), cryptic (C), release (R), and maturational (M) sites and at a newly discovered "tail" (T) site. The resulting mutants, called ICRM-pPR and ICRMT-pPR, were expressed in bacteria, denatured in urea, purified by immobilized metal affinity chromatography, and renatured by a two-step dialysis procedure and by a new method of sedimentation into glycerol gradients. The enzymatic activities of the pPR mutants were indistinguishable from that of IC-assemblin prepared in parallel for comparison, as determined by using a fluorogenic peptide cleavage assay, and approximated rates previously reported for purified assemblin. The percentage of active enzyme in the preparations was also comparable, as determined by using a covalent-binding suicide substrate. An unexpected finding was that, in the absence of the kosmotrope Na2SO4, optimal activity of pPR requires interaction through its scaffolding domain. We conclude that although the enzymatic activities of assemblin and its precursor are comparable, there may be differences in how their catalytic sites become fully activated.
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Affiliation(s)
- Edward J Brignole
- Virology Laboratories, The Department of Pharmacology & Molecular Sciences, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
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13
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Buisson M, Rivail L, Hernandez JF, Jamin M, Martinez J, Ruigrok RWH, Burmeister WP. Kinetics, inhibition and oligomerization of Epstein-Barr virus protease. FEBS Lett 2006; 580:6570-8. [PMID: 17118362 DOI: 10.1016/j.febslet.2006.11.006] [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] [Received: 10/12/2006] [Accepted: 11/06/2006] [Indexed: 01/28/2023]
Abstract
Epstein-Barr virus (EBV) is an omnipresent human virus causing infectious mononucleosis and EBV associated cancers. Its protease is a possible target for antiviral therapy. We studied its dimerization and enzyme kinetics with two enzyme assays based either on the release of paranitroaniline or 7-amino-4-methylcoumarin from labeled pentapeptide (Ac-KLVQA) substrates. The protease is in a monomer-dimer equilibrium where only dimers are active. In absence of citrate the K(d) is 20 microM and drops to 0.2 microM in presence of 0.5M citrate. Citrate increases additionally the activity of the catalytic sites. The inhibitory constants of different substrate derived peptides and alpha-keto-amide based inhibitors, which have at best a K(i) of 4 microM, have also been evaluated.
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Affiliation(s)
- Marlyse Buisson
- Institut de Virologie Moléculaire et Structurale, FRE 2854 CNRS-UJF, BP181, 38042 Grenoble Cedex 9, France
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14
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Nomura AM, Marnett AB, Shimba N, Dötsch V, Craik CS. Induced structure of a helical switch as a mechanism to regulate enzymatic activity. Nat Struct Mol Biol 2006; 12:1019-20. [PMID: 16244665 DOI: 10.1038/nsmb1006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Accepted: 09/19/2005] [Indexed: 11/09/2022]
Abstract
Herpesviruses encode a protease that is activated by homodimerization at high enzyme concentrations during lytic replication. The homodimer contains two active sites, which are distal from the dimer interface. Assignment of backbone NMR resonances and engineering of a redox switch show that two helices position a loop containing catalytic residues within each active site.
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Affiliation(s)
- Anson M Nomura
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143, USA
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15
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Cottier V, Barberis A, Lüthi U. Novel yeast cell-based assay to screen for inhibitors of human cytomegalovirus protease in a high-throughput format. Antimicrob Agents Chemother 2006; 50:565-71. [PMID: 16436711 PMCID: PMC1366920 DOI: 10.1128/aac.50.2.565-571.2006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The protease encoded by the human cytomegalovirus (HCMV) is an attractive target for antiviral drug development because of its essential function in viral replication. We describe here a cellular assay in the yeast Saccharomyces cerevisiae for the identification of small molecule inhibitors of HCMV protease by conditional growth in selective medium. In this system, the protease cleavage sequence is inserted into the N-(5'-phosphoribosyl)anthranilate isomerase (Trp1p), a yeast protein essential for cell proliferation in the absence of tryptophan. Coexpression of HCMV protease with the engineered Trp1p substrate in yeast cells results in site-specific cleavage and functional inactivation of the Trp1p enzyme, thereby leading to an arrest of cell proliferation. This growth arrest can be suppressed by the addition of validated HCMV protease inhibitors. The growth selection system presented here provides the basis for a high-throughput screen to identify HCMV protease inhibitors that are active in eukaryotic cells.
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Affiliation(s)
- Valérie Cottier
- ESBATech AG, Wagistr. 21, CH-8952 Zurich-Schlieren, Switzerland
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16
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McCartney SA, Brignole EJ, Kolegraff KN, Loveland AN, Ussin LM, Gibson W. Chemical Rescue of I-site Cleavage in Living Cells and in Vitro Discriminates between the Cytomegalovirus Protease, Assemblin, and Its Precursor, pUL80a. J Biol Chem 2005; 280:33206-12. [PMID: 16036911 DOI: 10.1074/jbc.m506876200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chemical rescue is an established approach that offers a directed strategy for designing mutant enzymes in which activity can be restored by supplying an appropriate exogenous compound. This method has been used successfully to study a broad range of enzymes in vitro, but its application to living systems has received less attention. We have investigated the feasibility of using chemical rescue to make a conditional-lethal mutant of the cytomegalovirus (CMV) maturational protease. The 28-kDa CMV serine protease, assemblin, has a Ser-His-His catalytic triad and an internal (I) cleavage site near its midpoint. We found that imidazole can restore I-site cleavage to mutants inactivated by replacing the critical active site His with Ala or with Gly, which rescued better. Comparable rescue was observed for counterpart mutants of the human and simian CMV assemblin homologs and occurred in both living cells and in vitro. Cleavage was established to be at the correct site by amino acid sequencing and proceeded at approximately 11%/h in bacteria and approximately 30%/h in vitro. The same mutations were unresponsive to chemical rescue in the context of the assemblin precursor, pUL80a. This catalytic difference distinguishes the two forms of the CMV protease.
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Affiliation(s)
- Stephen A McCartney
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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17
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Shimba N, Nomura AM, Marnett AB, Craik CS. Herpesvirus protease inhibition by dimer disruption. J Virol 2004; 78:6657-65. [PMID: 15163756 PMCID: PMC416554 DOI: 10.1128/jvi.78.12.6657-6665.2004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2003] [Accepted: 02/03/2004] [Indexed: 01/23/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV), like all herpesviruses, encodes a protease (KSHV Pr), which is necessary for the viral lytic cycle. Herpesvirus proteases function as obligate dimers; however, each monomer has an intact, complete active site which does not interact directly with the other monomer across the dimer interface. Protein grafting of an interfacial KSHV Pr alpha-helix onto a small stable protein, avian pancreatic polypeptide, generated a helical 30-amino-acid peptide designed to disrupt the dimerization of KSHV Pr. The chimeric peptide was optimized through protein modeling of the KSHV Pr-peptide complex. Circular dichroism analysis and gel filtration chromatography revealed that the rationally designed peptide adopts a helical conformation and is capable of disrupting KSHV Pr dimerization, respectively. Additionally, the optimized peptide inhibits KSHV Pr activity by 50% at a approximately 200-fold molar excess of peptide to KSHV Pr, and the dissociation constant was estimated to be 300 microM. Mutagenesis of the interfacial residue M197 to a leucine resulted in an inhibitory concentration which was twofold higher for KSHV Pr M197L than for KSHV Pr, in agreement with the model that the dimer interface is involved in peptide binding. These results indicate that the dimer interface, as well as the active sites, of herpesvirus proteases is a viable target for inhibiting enzyme activity.
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Affiliation(s)
- Nobuhisa Shimba
- Department of Pharmaceutical Chemistry, University of California-San Francisco, 600 16th St., Box 2280, San Francisco, CA 94143-2280, USA
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18
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Buisson M, Hernandez JF, Lascoux D, Schoehn G, Forest E, Arlaud G, Seigneurin JM, Ruigrok RWH, Burmeister WP. The crystal structure of the Epstein-Barr virus protease shows rearrangement of the processed C terminus. J Mol Biol 2002; 324:89-103. [PMID: 12421561 DOI: 10.1016/s0022-2836(02)01040-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Epstein-Barr virus (EBV) belongs to the gamma-herpesvirinae subfamily of the Herpesviridae. The protease domain of the assemblin protein of herpesviruses forms a monomer-dimer equilibrium in solution. The protease domain of EBV was expressed in Escherichia coli and its structure was solved by X-ray crystallography to 2.3A resolution after inhibition with diisopropyl-fluorophosphate (DFP). The overall structure confirms the conservation of the homodimer and its structure throughout the alpha, beta, and gamma-herpesvirinae. The substrate recognition could be modelled using information from the DFP binding, from a crystal contact, suggesting that the substrate forms an antiparallel beta-strand extending strand beta5, and from the comparison with the structure of a peptidomimetic inhibitor bound to cytomegalovirus protease. The long insert between beta-strands 1 and 2, which was disordered in the KSHV protease structure, was found to be ordered in the EBV protease and shows the same conformation as observed for proteases in the alpha and beta-herpesvirus families. In contrast to previous structures, the long loop located between beta-strands 5 and 6 is partially ordered, probably due to DFP inhibition and a crystal contact. It also contributes to substrate recognition. The protease shows a specific recognition of its own C terminus in a binding pocket involving residue Phe210 of the other monomer interacting across the dimer interface. This suggests conformational changes of the protease domain after its release from the assemblin precursor followed by burial of the new C terminus and a possible effect onto the monomer-dimer equilibrium. The importance of the processed C terminus was confirmed using a mutant protease carrying a C-terminal extension and a mutated release site, which shows different solution properties and a strongly reduced enzymatic activity.
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Affiliation(s)
- Marlyse Buisson
- Laboratoire de Virologie, Hôpital Michallon, BP 217, 38043 Grenoble Cedex 9, France
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