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Gavor E, Choong YK, Jobichen C, Mok YK, Kini RM, Sivaraman J. Structure of Aedes aegypti carboxypeptidase B1-inhibitor complex uncover the disparity between mosquito and non-mosquito insect carboxypeptidase inhibition mechanism. Protein Sci 2021; 30:2445-2456. [PMID: 34658092 PMCID: PMC8605369 DOI: 10.1002/pro.4212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 11/07/2022]
Abstract
Metallocarboxypeptidases (MCPs) in the mosquito midgut play crucial roles in infection, as well as in mosquito dietary digestion, reproduction, and development. MCPs are also part of the digestive system of plant-feeding insects, representing key targets for inhibitor development against mosquitoes/mosquito-borne pathogens or as antifeedant molecules against plant-feeding insects. Notably, some non-mosquito insect B-type MCPs are primarily insensitive to plant protease inhibitors (PPIs) such as the potato carboxypeptidase inhibitor (PCI; MW 4 kDa), an inhibitor explored for cancer treatment and insecticide design. Here, we report the crystal structure of Aedes aegypti carboxypeptidase-B1 (CPBAe1)-PCI complex and compared the binding with that of PCI-insensitive CPBs. We show that PCI accommodation is determined by key differences in the active-site regions of MCPs. In particular, the loop regions α6-α7 (Leu242 -Ser250 ) and β8-α8 (Pro269 -Pro280 ) of CPBAe1 are replaced by α-helices in PCI-insensitive insect Helicoverpa zea CPBHz. These α-helices protrude into the active-site pocket of CPBHz, restricting PCI insertion and rendering the enzyme insensitive. We further compared our structure with the only other PCI complex available, bovine CPA1-PCI. The potency of PCI against CPBAe1 (Ki = 14.7 nM) is marginally less than that of bovine CPA1 (Ki = 5 nM). Structurally, the above loop regions that accommodate PCI binding in CPBAe1 are similar to that of bovine CPA1, although observed changes in proteases residues that interact with PCI could account for the differences in affinity. Our findings suggest that PCI sensitivity is largely dictated by structural interference, which broadens our understanding of carboxypeptidase inhibition as a mosquito population/parasite control strategy.
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Affiliation(s)
- Edem Gavor
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Yeu Khai Choong
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Chacko Jobichen
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Yu Keung Mok
- Department of Biological SciencesNational University of SingaporeSingapore
| | - R. Manjunatha Kini
- Department of Biological SciencesNational University of SingaporeSingapore
- Department of Pharmacology, Yong Loo Lin School of MedicineNational University of SingaporeSingapore
| | - J. Sivaraman
- Department of Biological SciencesNational University of SingaporeSingapore
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Gavor E, Choong YK, Tulsian NK, Nayak D, Idris F, Sivaraman H, Ting DHR, Sylvie A, Mok YK, Kini RM, Sivaraman J. Structure of Aedes aegypti procarboxypeptidase B1 and its binding with Dengue virus for controlling infection. Life Sci Alliance 2021; 5:5/1/e202101211. [PMID: 34750241 PMCID: PMC8605224 DOI: 10.26508/lsa.202101211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/18/2021] [Accepted: 10/19/2021] [Indexed: 12/05/2022] Open
Abstract
Using high-resolution structure, we have characterized the substrate specificity of Aedes aegypti procarboxypeptidase B1 and provided mechanistic insights into the binding and inhibition of DENV Metallocarboxypeptidases play critical roles in the development of mosquitoes and influence pathogen/parasite infection of the mosquito midgut. Here, we report the crystal structure of Aedes aegypti procarboxypeptidase B1 (PCPBAe1), characterized its substrate specificity and mechanism of binding to and inhibiting Dengue virus (DENV). We show that the activated PCPBAe1 (CPBAe1) hydrolyzes both Arg- and Lys-substrates, which is modulated by residues Asp251 and Ser239. Notably, these residues are conserved in CPBs across mosquito species, possibly required for efficient digestion of basic dietary residues that are necessary for mosquito reproduction and development. Importantly, we characterized the interaction between PCPBAe1 and DENV envelope (E) protein, virus-like particles, and infectious virions. We identified residues Asp18A, Glu19A, Glu85, Arg87, and Arg89 of PCPBAe1 are essential for interaction with DENV. PCPBAe1 maps to the dimeric interface of the E protein domains I/II (Lys64–Glu84, Val238–Val252, and Leu278–Leu287). Overall, our studies provide general insights into how the substrate-binding property of mosquito carboxypeptidases could be targeted to potentially control mosquito populations or proposes a mechanism by which PCPBAe1 binds to and inhibits DENV.
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Affiliation(s)
- Edem Gavor
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Yeu Khai Choong
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Nikhil Kumar Tulsian
- Department of Biological Sciences, National University of Singapore, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Digant Nayak
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Fakhriedzwan Idris
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore
| | - Hariharan Sivaraman
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Donald Heng Rong Ting
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore
| | - Alonso Sylvie
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore
| | - Yu Keung Mok
- Department of Biological Sciences, National University of Singapore, Singapore
| | - R Manjunatha Kini
- Department of Biological Sciences, National University of Singapore, Singapore.,Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - J Sivaraman
- Department of Biological Sciences, National University of Singapore, Singapore
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Sillen M, Declerck PJ. Thrombin Activatable Fibrinolysis Inhibitor (TAFI): An Updated Narrative Review. Int J Mol Sci 2021; 22:ijms22073670. [PMID: 33916027 PMCID: PMC8036986 DOI: 10.3390/ijms22073670] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 03/26/2021] [Accepted: 03/29/2021] [Indexed: 01/02/2023] Open
Abstract
Thrombin activatable fibrinolysis inhibitor (TAFI), a proenzyme, is converted to a potent attenuator of the fibrinolytic system upon activation by thrombin, plasmin, or the thrombin/thrombomodulin complex. Since TAFI forms a molecular link between coagulation and fibrinolysis and plays a potential role in venous and arterial thrombotic diseases, much interest has been tied to the development of molecules that antagonize its function. This review aims at providing a general overview on the biochemical properties of TAFI, its (patho)physiologic function, and various strategies to stimulate the fibrinolytic system by interfering with (activated) TAFI functionality.
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Plug T, Meijers JCM. Structure-function relationships in thrombin-activatable fibrinolysis inhibitor. J Thromb Haemost 2016; 14:633-44. [PMID: 26786060 DOI: 10.1111/jth.13261] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Indexed: 11/30/2022]
Abstract
Thrombin-activatable fibrinolysis inhibitor (TAFI) is an important regulator in the balance of coagulation and fibrinolysis. TAFI is a metallocarboxypeptidase that circulates in plasma as zymogen. Activated TAFI (TAFIa) cleaves C-terminal lysine or arginine residues from peptide substrates. The removal of C-terminal lysine residues from partially degraded fibrin leads to reduced plasmin formation and thus attenuation of fibrinolysis. TAFI also plays a role in inflammatory processes via the removal of C-terminal arginine or lysine residues from bradykinin, thrombin-cleaved osteopontin, C3a, C5a and chemerin. TAFI has been studied extensively over the past three decades and recent publications provide a wealth of information, including crystal structures, mutants and structural data obtained with antibodies and peptides. In this review, we combined and compared available data on structure/function relationships of TAFI.
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Affiliation(s)
- T Plug
- Department of Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - J C M Meijers
- Department of Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
- Department of Plasma Proteins, Sanquin Research, Amsterdam, the Netherlands
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Yoshimoto N, Sasaki T, Sugimoto K, Ishii H, Yamamoto K. Design and characterization of a selenium-containing inhibitor of activated thrombin-activatable fibrinolysis inhibitor (TAFIa), a zinc-containing metalloprotease. J Med Chem 2012; 55:7696-705. [PMID: 22891675 DOI: 10.1021/jm300735t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Available therapies for thromboembolic disorders include thrombolytics, anticoagulants, and antiplatelets, but these are associated with complications such as bleeding. To develop an alternative drug which is clinically safe, we focused on activated thrombin-activatable fibrinolysis inhibitor (TAFIa) as the target molecule. TAFIa is a zinc-containing carboxypeptidase that significantly inhibits fibrinolysis. Here we designed and synthesized selenium-containing compounds 5-13 to discover novel TAFIa inhibitors having a superior zinc-coordinating group. Compounds 5-13 significantly inhibited TAFIa activity (IC(50) 2.2 × 10(-12) M - 2.6 × 10(-6) M). We found that selenol is a better functional group than thiol for coordinating to zinc at the active site of TAFIa. Furthermore, compound 12, which has an amino-chloro-pyridine ring, was found to be a potent and selective TAFIa inhibitor that lacks carboxypeptidase N inhibitory activity. Therefore, compound 12 is a promising candidate for the treatment of thromboembolic disorders. This is the first report of a selenium-containing inhibitor for TAFIa.
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Affiliation(s)
- Nobuko Yoshimoto
- High Technology Research Center, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan.
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Mishra N, Buelens K, Theyskens S, Compernolle G, Gils A, Declerck PJ. Increased zymogen activity of thrombin-activatable fibrinolysis inhibitor prolongs clot lysis. J Thromb Haemost 2012; 10:1091-9. [PMID: 22498006 DOI: 10.1111/j.1538-7836.2012.04738.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND OBJECTIVES Thrombin-activatable fibrinolysis inhibitor (TAFI) is a zymogen that can be activated by proteolytic cleavage into the active enzyme TAFIa. Hydrolysis of the C-terminal lysines on fibrin by TAFIa results in a down-regulation of fibrinolysis. Recent studies demonstrated that the zymogen also exerts an intrinsic enzymatic activity. Our objective was to identify and characterize zymogen-stimulatory nanobodies. METHODS AND RESULTS The screening of 24 nanobodies against TAFI revealed that two nanobodies (i.e. Vhh-TAFI-a51 and Vhh-TAFI-i103) were able to stimulate the zymogen activity 10- to 21-fold compared with the baseline zymogen activity of TAFI. The increase in catalytic efficiency can be attributed mainly to an increased catalytic rate, as no change in the K(M) -value was observed. The stability, the susceptibility towards PTCI and GEMSA and the kinetics of the stimulated zymogen activity differ significantly from those of TAFIa activity. Epitope mapping revealed that both Asp(75) and Thr(301) are major determinants in the binding of these nanobodies to TAFI. Localization of the epitope strongly suggests that this instability is as a result of a disruption of the stabilizing interactions between the activation peptide and the dynamic flap region (residues 296-350). In TAFI-depleted plasma reconstituted with a non-activatable variant of TAFI (TAFI-R92A), clot lysis could be prolonged by nanobody-induced stimulation of its zymogen activity as well as by increasing its concentration. CONCLUSIONS Increasing the zymogen activity of TAFI results in an antifibrinolytic effect.
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Affiliation(s)
- N Mishra
- Laboratory for Pharmaceutical Biology, Katholieke Universiteit, Leuven, Belgium
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