Cloning and characterization of the cDNA encoding human adenylosuccinate synthetase

Abstract

Adenylosuccinate synthetase (AS) catalyzes the first committed step in the conversion of IMP to AMP. A cDNA was isolated from a human liver library which encodes a protein of 455 amino acids (M, or49.925). Alignments of human, mouse, Dicryostelium discoidrum and E. co/i AS sequences identify a number of invariant residues which are likely to be important for structure and/or catalysis. The human AS sequence was also 19% ideritical to the human urea cycle enzyme, arginosuccirlate synthetase (ASS), which catalyzes a chemically similar reaction, Both human liver and HeLa AS mRNA showed signals of 2.3 and 2.8 kb. An unmodified N-terminus is required for function of the human AS enzyme in E. c&mutants lacking the bacterial enzyme. The human cDNA provides a means to assess the possible role of AS abnormalities in unclassified, idiopathic cases of gout.Recombinant DNA; De novo purinc nucleotide synthesis; Gout

Growth factor – regulated expression of enzymes involved in nucleotide biosynthesis: a novel mechanism of growth factor action

“…We obtained a 293 bp cDNA fragment of the human ADS. This sequence is 100% identical to the sequence (nt 219 ± 511) published by Powell et al (1992). Furthermore, we cloned fragments encoding parts of PRPS subunit one (398 bp; nt 183 ± 580; Sonoda et al, 1991), APRT (368 bp; nt 220 ± 587; Iwahana et al, 1993a), HPRT (326 bp; nt 355 ± 680; Jolly et al, 1983), and of the multifunctional protein CAD (310 bp; nt 871 ± 1180; Iwahana et al, 1996).…”

Adenylosuccinate Syntheatase: Recent Developments

“…In humans, a single AMPSase cDNA has been isolated from liver RNA that probably specifies the nonmuscle isozyme: it shows more than 90% amino acid sequence identity with the murine nonmuscle isozyme and less than 75% identity with the murine muscle isozyme (Powell et al, 1992). The human AMPSase cDNA hybridizes to two mRNA size classes, also consistent with its identification as the nonmuscle isozyme.…”

Variations in the Response of Mouse Isozymes of Adenylosuccinate Synthetase to Inhibitors of Physiological Relevance

“…Adenylosuccinate synthetases are well conserved through evolution, exhibiting, for instance, ϳ40% sequence identity between eubacteria and mammals (2,3). Eukaryotic synthetases differ from their prokaryotic counterparts by the presence of N-terminal leader sequences (ϳ30 residues) and by truncations (ϳ10 residues) at their C termini (2)(3)(4). The synthetase catalyzes the first committed step in the de novo biosynthesis of AMP from IMP and, in vertebrates, is also a component of the purine nucleotide cycle (PNC) 1 (2,(5)(6)(7).…”

“…save in one instance (30), specific activities significantly lower than that of AdSS1 (2,6). Human and mouse AdSS2 have been cloned (3,4) and the latter overexpressed in COS (African green monkey kidney) cells, but no kinetic characterization was reported (3). Native states of oligomerization for each isozyme remain ambiguous, as reports of monomeric and dimeric AdSS1 and AdSS2 are in the literature (8, 10, 29 -31).…”