ACE2 X-Ray Structures Reveal a Large Hinge-bending Motion Important for Inhibitor Binding and Catalysis (original) (raw)
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Circulation Research, 2000
ACE2, the first known human homologue of angiotensin-converting enzyme (ACE), was identified from 5Ј sequencing of a human heart failure ventricle cDNA library. ACE2 has an apparent signal peptide, a single metalloprotease active site, and a transmembrane domain. The metalloprotease catalytic domains of ACE2 and ACE are 42% identical, and comparison of the genomic structures indicates that the two genes arose through duplication. In contrast to the more ubiquitous ACE, ACE2 transcripts are found only in heart, kidney, and testis of 23 human tissues examined. Immunohistochemistry shows ACE2 protein predominantly in the endothelium of coronary and intrarenal vessels and in renal tubular epithelium. Active ACE2 enzyme is secreted from transfected cells by cleavage N-terminal to the transmembrane domain. Recombinant ACE2 hydrolyzes the carboxy terminal leucine from angiotensin I to generate angiotensin 1-9, which is converted to smaller angiotensin peptides by ACE in vitro and by cardiomyocytes in culture. ACE2 can also cleave des-Arg bradykinin and neurotensin but not bradykinin or 15 other vasoactive and hormonal peptides tested. ACE2 is not inhibited by lisinopril or captopril. The organ-and cell-specific expression of ACE2 and its unique cleavage of key vasoactive peptides suggest an essential role for ACE2 in the local renin-angiotensin system of the heart and kidney. The full text of this article is available at http://www.circresaha.org.
Frontiers in Pharmacology, 2015
Angiotensin converting enzyme 2 (ACE2) is a zinc carboxypeptidase involved in the reninangiotensin system (RAS) and inactivates the potent vasopressive peptide angiotensin II (Ang II) by removing the C-terminal phenylalanine residue to yield Ang1-7. This conversion inactivates the vasoconstrictive action of Ang II and yields a peptide that acts as a vasodilatory molecule at the Mas receptor and potentially other receptors. Given the growing complexity of RAS and level of cross-talk between ligands and their corresponding enzymes and receptors, the design of molecules with selectivity for the major RAS binding partners to control cardiovascular tone is an ongoing challenge. In previous studies we used single β-amino acid substitutions to modulate the structure of Ang II and its selectivity for ACE2, AT 1 R, and angiotensin type 2 (AT 2 R) receptor. We showed that modification at the C-terminus of Ang II generally resulted in more pronounced changes to secondary structure and ligand binding, and here, we further explore this region for the potential to modulate ligand specificity. In this study, (1) a library of 47 peptides derived from the C-terminal tetrapeptide sequence (-IHPF) of Ang II was synthesized and assessed for ACE2 binding, (2) the terminal group requirements for high affinity ACE2 binding were explored by and Nand C-terminal modification, (3) high affinity ACE2 binding chimeric AngII analogs were then synthesized and assessed, (4) the structure of the full-length Ang II analogs were assessed by circular dichroism, and (5) the Ang II analogs were assessed for AT 1 R/AT 2 R selectivity by cell-based assays. Studies on the C-terminus of Ang II demonstrated varied specificity at different residue positions for ACE2 binding and four Ang II chimeric peptides were identified as selective ligands for the AT 2 receptor. Overall, these results provide insight into the residue and structural requirements for ACE2 binding and angiotensin receptor selectivity.
FEBS Journal, 2005
Angiotensin-converting enzyme-2 (ACE2) is a membrane protein with its active site exposed to the extracellular surface of endothelial cells, the renal tubular epithelium and also the epithelia of the lung and the small intestine . Here ACE2 is poised to metabolize circulating peptides which may include angiotensin II, a potent vasoconstrictor and the product of angiotensin I cleavage by angiotensin-converting enzyme (ACE; EC 3.4.15.1) . Indeed, ACE2 has been implicated in the regulation of heart and renal function where it is proposed to control the concentrations of angiotensin II relative to its hypotensive metabolite, angiotensin-(1-7) . Most recently, ACE2 has been identified as a functional receptor for the coronavirus which causes the severe acute respiratory syndrome (SARS) . For recent reviews, see .
2011
Human ACE (angiotensin-I-converting enzyme) has long been regarded as an excellent target for the treatment of hypertension and related cardiovascular diseases. Highly potent inhibitors have been developed and are extensively used in the clinic. To develop inhibitors with higher therapeutic efficacy and reduced side effects, recent efforts have been directed towards the discovery of compounds able to simultaneously block more than one zinc metallopeptidase (apart from ACE) involved in blood pressure regulation in humans, such as neprilysin and ECE-1 (endothelinconverting enzyme-1). In the present paper, we show the first structures of testis ACE [C-ACE, which is identical with the C-domain of somatic ACE and the dominant domain responsible for blood pressure regulation, at 1.97Å (1 Å = 0.1 nm)] and the N-domain of somatic ACE (N-ACE, at 2.15Å) in complex with a highly potent and selective dual ACE/ECE-1 inhibitor. The structural determinants revealed unique features of the binding of two molecules of the dual inhibitor in the active site of C-ACE. In both structures, the first molecule is positioned in the obligatory binding site and has a bulky bicyclic P 1 residue with the unusual R configuration which, surprisingly, is accommodated by the large S 2 pocket. In the C-ACE complex, the isoxazole phenyl group of the second molecule makes strong pi-pi stacking interactions with the amino benzoyl group of the first molecule locking them in a 'hand-shake' conformation. These features, for the first time, highlight the unusual architecture and flexibility of the active site of C-ACE, which could be further utilized for structure-based design of new C-ACE or vasopeptidase inhibitors.
Current Topics in Medicinal Chemistry, 2004
Angiotensin-I Converting Enzyme (ACE) is a Zinc Metallopeptidase of which the three-dimensional stucture was unknown until recently, when the Xray structure of testis isoform (C-terminal domain of somatic) was determined. ACE plays an important role in the regulation of blood pressure due to its action in the frame of the Renin-Angiotensin System. Efforts for the specific inhibition of the catalytic function of this enzyme have been made on the basis of the Xray structures of other enzymes with analogous efficacy in the hydrolytic cleavage of peptide substrate terminal fragments. Angiotensin-I Converting Enzyme bears the sequence and topology characteristics of the well-known gluzincins, a sub-family of zincins metallopeptidases and these similarities are exploited in order to reveal common structural elements among these enzymes. 3D homology models are also built using the X-ray structure of Thermolysin as template and peptide models that represent the amino acid sequence of the ACE's two catalytic, zinc-containing sites are designed and synthesized. Conformational analysis of the zinc-free and zinc-bound peptides through high resolution 1 H NMR Spectroscopy provides new insights into the solution structure of ACE catalytic centers. Structural properties of these peptides could provide valuable information towards the design and preparation of new potent ACE inhibitors.
Experimental Physiology, 2008
Angiotensin-converting enzyme 2 (ACE2), a homologue of angiotensin-converting enzyme (ACE), converts angiotensin (Ang) I to Ang(1−9) and Ang II to Ang(1−7), but does not directly process Ang I to Ang II. Cardiac function is compromised in ACE2 null mice; however, the importance of ACE2 in the processing of angiotensin peptides within the murine heart is not known. We determined the metabolism of angiotensins in wild-type (WT), ACE (ACE −/−) and ACE2 null mice (ACE2 −/−). Angiotensin II was converted almost exclusively to Ang(1−7) in the cardiac membranes of WT and ACE −/− strains, although generation of Ang(1−7) was greater in the ACE −/− mice (27.4 ± 4.1 versus 17.5 ± 3.2 nmol −1 mg h −1 for WT). The ACE2 inhibitor MLN4760 significantly attenuated Ang II metabolism and the subsequent formation of Ang(1−7) in both strains. In the ACE2 −/− hearts, Ang II metabolism and the generation of Ang(1−7) were significantly attenuated; however, the ACE2 inhibitor reduced the residual Ang(1−7)-forming activity in this strain. Angiotensin I was primarily converted to Ang(1−9) (WT, 28.9 ± 3.1 nmol −1 mg h −1 ; ACE −/− , 49.8 ± 5.3 nmol −1 mg h −1 ; and ACE2 −/− , 35.9 ± 5.4 nmol −1 mg h −1) and to smaller quantities of Ang(1−7) and Ang II. Although the ACE2 inhibitor had no effect on Ang(1−9) formation, the carboxypeptidase A inhibitor benzylsuccinate essentially abolished the formation of Ang(1−9) and increased the levels of Ang I in cardiac membranes. In conclusion, our studies in the murine heart suggest that ACE2 is the primary pathway for the metabolism of Ang II and the subsequent formation of Ang(1−7), a peptide that, in contrast to Ang II, exhibits both antifibrotic and antiproliferative actions.
Journal of Computer-Aided Molecular Design, 1987
Previous structure-activity studies of captopril and related active angiotensin-converting enzyme (ACE) inhibitors have led to the conclusion that the basic structural requirements for inhibition of ACE involve (a) a terminal carboxyl group; (b) an amido carbonyl group; and (c) different types of effective zinc (Zn) ligand functional groups. Such structural requirements common to a set of compounds acting at the same receptor have been used to define a pharmacophoric pattern of atoms or groups of atoms mutually oriented in space that is necessary for ACE inhibition from a stereochemical point of view. A unique pharmacophore model (within the resolution of approximately 0.15 A) was observed using a method for systematic search of the conformational hyperspace available to the 28 structurally different molecules under study. The method does not assume a common molecular framework, and, therefore, allows comparison of different compounds that is independent of their absolute orientation.
Biological Chemistry, 2014
Somatic angiotensin-I converting enzyme (sACE) has an essential role in the regulation of blood pressure and electrolyte fluid homeostasis. It is a zinc protease that cleaves angiotensin-I (AngI), bradykinin, and a broad range of other signalling peptides. The enzyme activity is provided by two homologous domains (N- and C-), which display clear differences in substrate specificities and chloride activation. The presence of chloride ions in sACE and its unusual role in activity was identified early on in the characterisation of the enzyme. The molecular mechanisms of chloride activation have been investigated thoroughly through mutagenesis studies and shown to be substrate-dependent. Recent results from X-ray crystallography structural analysis have provided the basis for the intricate interactions between ACE, its substrate and chloride ions. Here we describe the role of chloride ions in human ACE and its physiological consequences. Insights into the chloride activation of the N- a...