Adenylosuccinate synthase

In molecular biology, adenylosuccinate synthase (or adenylosuccinate synthetase) (EC 6.3.4.4) is an enzyme that plays an important role in purine biosynthesis, by catalysing the guanosine triphosphate (GTP)-dependent conversion of inosine monophosphate (IMP) and aspartic acid to guanosine diphosphate (GDP), phosphate and N(6)-(1,2-dicarboxyethyl)-AMP. Adenylosuccinate synthetase has been characterised from various sources ranging from Escherichia coli (gene purA) to vertebrate tissues. In vertebrates, two isozymes are present: one involved in purine biosynthesis and the other in the purine nucleotide cycle.

Adenylosuccinate synthase
Adenylosuccinate synthetase dimer, Human
Identifiers
EC no.	6.3.4.4
CAS no.	9023-57-8
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

Adenylsucc_synt
structures of adenylosuccinate synthetase from Triticum aestivum and Arabidopsis thaliana
Identifiers
Symbol	Adenylsucc_synt
Pfam	PF00709
Pfam clan	CL0023
InterPro	IPR001114
PROSITE	PDOC00444
SCOP2	1ade / SCOPe / SUPFAM
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Structure

The crystal structure of adenylosuccinate synthetase from E. coli reveals that the dominant structural element of each monomer of the homodimer is a central beta-sheet of 10 strands. The first nine strands of the sheet are mutually parallel with right-handed crossover connections between the strands. The 10th strand is antiparallel with respect to the first nine strands. In addition, the enzyme has two antiparallel beta-sheets, composed of two strands and three strands each, 11 alpha-helices and two short 3₁₀-helices. Further, it has been suggested that the similarities in the GTP-binding domains of the synthetase and the p21ras protein are an example of convergent evolution of two distinct families of GTP-binding proteins.^[1] Structures of adenylosuccinate synthetase from Triticum aestivum and Arabidopsis thaliana when compared with the known structures from E. coli reveals that the overall fold is very similar to that of the E. coli protein.^[2]

Isozymes

Humans express two adenylosuccinate synthase isozymes:

adenylosuccinate synthase Identifiers Symbol ADSS NCBI gene 159 HGNC 292 OMIM 103060 RefSeq NM_001126 UniProt P30520 Other data EC number 6.3.4.4 Locus Chr. 1 q44 Search for Structures Swiss-model Domains InterPro

adenylosuccinate synthase like 1 Identifiers Symbol ADSSL1 NCBI gene 122622 HGNC 20093 OMIM 612498 RefSeq NM_152328 UniProt Q8N142 Other data EC number 6.3.4.4 Locus Chr. 14 q32.33 Search for Structures Swiss-model Domains InterPro

External links

• Adenylosuccinate+synthase at the U.S. National Library of Medicine Medical Subject Headings (MeSH)