Regulation ofN-Arginine Dibasic Convertase Activity by Amines:  Putative Role of a Novel Acidic Domain as an Amine Binding Site

Abstract

Peptide sequence analysis and cDNA cloning indicate that a previously described mouse arginine-specific dibasic cleaving enzyme (dynorphin converting enzyme) [Csuhai et al. (1995) Biochemistry 34, 12411] is the homologue of N-arginine dibasic convertase (NRDc) isolated from rat testis [Chesneau et al. (1994) J. Biol. Chem. 269, 2056]. A mouse NRDc cDNA exhibited 98% amino acid identity with the rat cDNA. However, within a 74 residue acidic stretch, this identity drops to 82%. Likewise, the corresponding acidic stretch of human NRDc is only 73% identical with that of rat NRDc. To reconcile previously observed kinetic differences between rat and mouse NRDc, the hydrolysis of peptide substrates by the rat, human, and mouse enzymes was compared using phosphate and Tris as buffers. Although the three NRDc's behaved similarly, Tris had a pronounced effect on the kinetics of peptide hydrolysis. With BAM-8, alpha-neoendorphin, and dynorphin B as substrates, Tris increased KM up to 40-fold with little change in Vmax, while with dynorphin A or somatostatin 28 as substrate, Tris caused a decrease in KM of up to 100 fold, again with only a modest change in Vmax. Other amines, including the polyamines putrescine, spermidine, and spermine, all affected NRD convertase activity. It is proposed that amines bind to the acidic stretch found in NRDc, and that quantitative differences in the sensitivity to amines between the rat, mouse, and human enzymes can be at least partially accounted for by differences in their acidic stretch. The role of polyamines as physiological modulators of N-arginine dibasic convertase is considered.

Reduced neuronal co-localisation of nardilysin and the putative α-secretases ADAM10 and ADAM17 in Alzheimer’s disease and Down syndrome brains

“…In this way, NRDc might contribute to the dysregulation of dynorphins in AD (Yakovleva et al 2007) and, possibly, to the elevated levels of the isoform somatostatin-28 Winsky-Sommerer et al 2003), which appear in parallel to the well-documented general somatostatin deficit in AD (Rossor et al 1984;Beal et al 1987;Mouradian et al 1991;Dournaud et al 1995). Although there is only little, if any, overlap of NRDc and somatostatin-28 immunoreactive nerve cell bodies in human brain (Bernstein et al 2007), a reduced somatostatin-28 metabolising function of NRDc (Csuhai et al 1998) cannot be ruled out in AD. In addition, NRDc has been demonstrated to interact with p42 IP4 /centaurin-α1 (Stricker et al 2006), which seems to play a role in AD Bernstein 2002, 2004).…”

Studies on the Subsite Specificity of Rat Nardilysin (N-Arginine Dibasic Convertase)

“…It has been suggested that this acidic domain might play a role in the regulation of nardilysin activity by forming charge-charge complexes with other cellular components (6,7).…”

Gene expression of the dibasic-pair cleaving enzyme NRD convertase (N-arginine dibasic convertase) is differentially regulated in the GH3 pituitary and Mat-Lu prostate cell lines

“…Rat, human and mouse cDNA sequences encoding NRD-C have been isolated [14,[18][19][20], and the deduced amino acid sequences have revealed that the enzyme is part of a large family of metalloendopeptidases -the M16 family (using the nomenclature of Rawlings and Barrett [21,22]). Many of the enzymes in this family have been implicated in prohormone or proprotein processing events.…”

“…It has been proposed that this acidic stretch might be a target for polyamines, which have been shown to inhibit the binding of rat, mouse and human NRD-C to its substrates and to control the activity of the enzyme [18,34]. It has been reported that expression of the enzyme is modulated by retinoic acid in human neuroblastoma cell lines and that this retinoic acid-responsiveness might be mediated by a retinoic acid-responsive element within the promoter of the NRD-C gene [35].…”