4c2q | pdb_00004c2q
Crystal structure of human testis angiotensin-I converting enzyme mutant R522K
Structural highlights
Disease[ACE_HUMAN] Genetic variations in ACE may be a cause of susceptibility to ischemic stroke (ISCHSTR) [MIM:601367]; also known as cerebrovascular accident or cerebral infarction. A stroke is an acute neurologic event leading to death of neural tissue of the brain and resulting in loss of motor, sensory and/or cognitive function. Ischemic strokes, resulting from vascular occlusion, is considered to be a highly complex disease consisting of a group of heterogeneous disorders with multiple genetic and environmental risk factors.[1] Defects in ACE are a cause of renal tubular dysgenesis (RTD) [MIM:267430]. RTD is an autosomal recessive severe disorder of renal tubular development characterized by persistent fetal anuria and perinatal death, probably due to pulmonary hypoplasia from early-onset oligohydramnios (the Potter phenotype).[2] Genetic variations in ACE are associated with susceptibility to microvascular complications of diabetes type 3 (MVCD3) [MIM:612624]. These are pathological conditions that develop in numerous tissues and organs as a consequence of diabetes mellitus. They include diabetic retinopathy, diabetic nephropathy leading to end-stage renal disease, and diabetic neuropathy. Diabetic retinopathy remains the major cause of new-onset blindness among diabetic adults. It is characterized by vascular permeability and increased tissue ischemia and angiogenesis. Defects in ACE are a cause of susceptibility to intracerebral hemorrhage (ICH) [MIM:614519]. A pathological condition characterized by bleeding into one or both cerebral hemispheres including the basal ganglia and the cerebral cortex. It is often associated with hypertension and craniocerebral trauma. Intracerebral bleeding is a common cause of stroke.[3] Function[ACE_HUMAN] Converts angiotensin I to angiotensin II by release of the terminal His-Leu, this results in an increase of the vasoconstrictor activity of angiotensin. Also able to inactivate bradykinin, a potent vasodilator. Has also a glycosidase activity which releases GPI-anchored proteins from the membrane by cleaving the mannose linkage in the GPI moiety. Publication Abstract from PubMedSomatic angiotensin-converting enzyme (sACE), a key regulator of blood pressure and electrolyte fluid homeostasis, cleaves the vasoactive angiotensin-I (AngI), bradykinin, and a number of other physiologically relevant peptides. sACE consists of two homologous and catalytically active N and C domains which display marked differences in substrate specificities and chloride activation. A series of single substitution mutants were generated and evaluated under varying chloride concentrations using isothermal titration calorimetry (ITC). The X-ray crystal structures of the mutants provided details on the chloride-dependent interactions with ACE. Chloride binding in the chloride 1 pocket of C-domain ACE was found to affect positioning of residues from the active site. Analysis of the chloride 2 pocket R522Q and R522K mutations revealed the key interactions with the catalytic site that are stabilized via chloride coordination of R522. Substrate interactions in the S2 sub-site were shown to affect chloride affinity in the chloride 2 pocket. The E403-K118 salt bridge in C-domain ACE was shown to stabilize the hinge-bending region and reduce chloride affinity by constraining the chloride 2 pocket. This work demonstrated that substrate composition to the C-terminal side of the scissile bond, as well as interactions of larger substrates in the S2 sub-site, moderate chloride affinity in the chloride 2 pocket of the ACE C-domain, providing a rationale for the substrate selective nature of chloride dependence in ACE and how this varies between the N and C domains. Molecular and Thermodynamic Mechanisms of the Chloride Dependent Human Angiotensin-I Converting Enzyme (ACE).,Yates CJ, Masuyer G, Schwager SL, Mohd A, Sturrock ED, Acharya KR J Biol Chem. 2013 Dec 2. PMID:24297181[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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