An Angiotensin I-Converting Enzyme Mutation (Y465D) Causes a Dramatic Increase in Blood ACE via Accelerated ACE Shedding

Abstract

BackgroundAngiotensin I-converting enzyme (ACE) metabolizes a range of peptidic substrates and plays a key role in blood pressure regulation and vascular remodeling. Thus, elevated ACE levels may be associated with an increased risk for different cardiovascular or respiratory diseases. Previously, a striking familial elevation in blood ACE was explained by mutations in the ACE juxtamembrane region that enhanced the cleavage-secretion process. Recently, we found a family whose affected members had a 6-fold increase in blood ACE and a Tyr465Asp (Y465D) substitution, distal to the stalk region, in the N domain of ACE.Methodology/Principal FindingsHEK and CHO cells expressing mutant (Tyr465Asp) ACE demonstrate a 3- and 8-fold increase, respectively, in the rate of ACE shedding compared to wild-type ACE. Conformational fingerprinting of mutant ACE demonstrated dramatic changes in ACE conformation in several different epitopes of ACE. Cell ELISA carried out on CHO-ACE cells also demonstrated significant changes in local ACE conformation, particularly proximal to the stalk region. However, the cleavage site of the mutant ACE - between Arg1203 and Ser1204 - was the same as that of WT ACE. The Y465D substitution is localized in the interface of the N-domain dimer (from the crystal structure) and abolishes a hydrogen bond between Tyr465 in one monomer and Asp462 in another.Conclusions/SignificanceThe Y465D substitution results in dramatic increase in the rate of ACE shedding and is associated with significant local conformational changes in ACE. These changes could result in increased ACE dimerization and accessibility of the stalk region or the entire sACE, thus increasing the rate of cleavage by the putative ACE secretase (sheddase).

A Modern Understanding of the Traditional and Nontraditional Biological Functions of Angiotensin-Converting Enzyme

“…These studies allow the representation of mature human ACE, as shown in Fig. 1 (Danilov et al, 2011). The N-domain of the molecule begins with Leu1 and extends to Pro601 .…”

“…Model of human somatic ACE. This model is a three-dimensional reconstruction of the electron microscopic appearance of porcine somatic ACE (the net) combined with available human X-ray crystal structures (Chen et al, 2010;Danilov et al, 2011). It shows the ACE N-domain (Leu1-Pro601), linker region (Pro602-Asp612), C-domain (Leu613--Pro1193), stalk region (Gln1194-Arg1227), transmembrane segment (Val1228-Ser1248), and intracellular domain (Gln1249-Ser1277) Corradi et al, 2006).…”

Pharmarcogenetic Mechanism of ACE I/D Polymorphism Adversely Responding to ACE Inhibitors in Regulating the ACE Promoter Activity in Neurons

“…The second vital question is whether the secreted ACE in serum could represent the amount of all ACE protein expressed from all tissues of the individual. Recently, a study provided an important evidence that the secreted ACE in human serum is very minor part of expressed ACE in comparison to membrane-bound ACE [47]. Besides, Fagyas and his colleagues [48,49] showed that most of the secreted ACE in body fluid are blocked by natural ACE inhibitors in serum (e.g., serum albumins).…”

Shedding the load of hypertension: The proteolytic processing of angiotensin-converting enzyme

“…Collaboration of our group with the University of Chicago has revealed a third ACE mutation present in a family of individuals where the affected members suffer from intermittent nausea, vomiting, fatigue and depression. 13 Investigation revealed dramatically elevated levels of plasma ACE (approximately 10-fold higher than normal) associated with a mutation in the ACE ectodomain (Y465D). Expression of recombinant ACE with this mutation in mammalian cells confirmed that the Y465D mutation causes increased ACE shedding.…”

“…Expression of recombinant ACE with this mutation in mammalian cells confirmed that the Y465D mutation causes increased ACE shedding. 13 This is remarkable because the mutation is distant from the stalk cleavage site and probably causes a change in the relative orientation of the two domains, allowing better access of the sheddase.…”