Structures of soluble rabbit neprilysin complexed with phosphoramidon or thiorphan

Aβ31-35 Decreases Neprilysin-Mediated Alzheimer's Amyloid-β Peptide Degradation

Alzheimer's disease is associated with the deposition of extracellular senile plaques, made primarily of amyloid-β (Aβ), particularly peptides Aβ_1-42 and Aβ_1-40. Neprilysin, or neutral endopeptidase (NEP), catalyzes proteolysis of the amyloid peptides (Aβ) and is recognized as one of the major regulators of the levels of these peptides in the brain, preventing Aβ accumulation and plaque formation. Here, we used a combination of techniques to elucidate the mechanism of Aβ binding and cleavage by NEP. Our findings indicate that the Aβ_31-X cleavage products remain bound to the neprilysin active site, reducing proteolytic activity. Interestingly, it was already shown that this Aβ_31-35 sequence is also critical for recognition of Aβ peptides by other targets, such as the serpin-enzyme complex receptor in neuronal cells.

Structural analysis of Mycobacterium tuberculosis M13 metalloprotease Zmp1 open states

Zinc metalloprotease 1 (Zmp1), a Mycobacterium tuberculosis 75 kDa secreted enzyme, mediates key stages of tuberculosis disease progression. The biological activity of Zmp1 presumably stems from its ability to degrade bacterium- and/or host-derived peptides. The crystal structures of Zmp1 and related M13 metalloproteases, such as neprilysin and endothelin-converting enzyme-1 were determined only in the closed conformation, which cannot capture substrates or release proteolytic products. Thus, the mechanisms of substrate binding and selectivity remain elusive. Here we report two open-state cryo-EM structures of Zmp1, revealed by our SAXS analysis to be the dominant states in solution. Our structural analyses reveal how ligand binding induces a conformational switch in four linker regions to drive the rigid body motion of the D1 and D2 domains, which form the sizable catalytic chamber. Furthermore, they offer insights into the catalytic cycle and mechanism of substrate recognition of M13 metalloproteases for future therapeutic innovations.

Molecular Basis for Omapatrilat and Sampatrilat Binding to Neprilysin-Implications for Dual Inhibitor Design with Angiotensin-Converting Enzyme

Neprilysin (NEP) and angiotensin-converting enzyme (ACE) are two key zinc-dependent metallopeptidases in the natriuretic peptide and kinin systems and renin–angiotensin–aldosterone system, respectively. They play an important role in blood pressure regulation and reducing the risk of heart failure. Vasopeptidase inhibitors omapatrilat and sampatrilat possess dual activity against these enzymes by blocking the ACE-dependent conversion of angiotensin I to the potent vasoconstrictor angiotensin II while simultaneously halting the NEP-dependent degradation of vasodilator atrial natriuretic peptide. Here, we report crystal structures of omapatrilat, sampatrilat, and sampatrilat-ASP (a sampatrilat analogue) in complex with NEP at 1.75, 2.65, and 2.6 Å, respectively. A detailed analysis of these structures and the corresponding structures of ACE with these inhibitors has provided the molecular basis of dual inhibitor recognition involving the catalytic site in both enzymes. This new information will be very useful in the design of safer and more selective vasopeptidase inhibitors of NEP and ACE for effective treatment in hypertension and heart failure.