Disease relevance of purA

• Adenylosuccinate synthetase (EC 6.3.4.4), encoded by the purA gene of Escherichia coli K12, catalyzes the synthesis of adenylosuccinate (SAMP) from IMP, the first committed step in AMP biosynthesis [1].
• Cloning and sequence of Bacillus subtilis purA and guaA, involved in the conversion of IMP to AMP and GMP [2].
• Attenuation, persistence, and vaccine potential of an Edwardsiella ictaluri purA mutant [3].

High impact information on purA

• We found that purified MarA was sufficient in vitro to repress transcription of both purA and hdeA [4].
• Vertebrates have acidic and basic isozymes of adenylosuccinate synthetase, which participate in the first committed step of de novo AMP biosynthesis and/or the purine nucleotide cycle [5].
• IMP Alone Organizes the Active Site of Adenylosuccinate Synthetase from Escherichia coli [6].
• Determinants of L-aspartate and IMP recognition in Escherichia coli adenylosuccinate synthetase [7].
• Guanosine 5'-diphosphate 3'-diphosphate (ppGpp), a pleiotropic effector of the stringent response, potently inhibits adenylosuccinate synthetase from Escherichia coli as an allosteric effector and/or as a competitive inhibitor with respect to GTP [8].

Chemical compound and disease context of purA

• Evidence for an arginine residue at the substrate binding site of Escherichia coli adenylosuccinate synthetase as studied by chemical modification and site-directed mutagenesis [9].
• Incubation of adenylosuccinate synthetase from Escherichia coli with low concentrations of pyridoxal 5'-phosphate (PLP) resulted in a rapid loss of activity (92%), concomitant with the formation of a Schiff base [10].
• Chemical modification of adenylosuccinate synthetase from Escherichia coli with phenylglyoxal resulted in an inhibition of enzyme activity with a second-order rate constant of 13.6 M-1 min-1 [9].
• Because the consensus sequence GXXXXGK(T/S) has been found in many GTP-binding proteins, isoleucine at position 19 in the E. coli adenylosuccinate synthetase was changed to threonine to produce the sequence GDEGKGKT [11].
• Crystal structures of adenylosuccinate synthetase from Escherichia coli complexed with GDP, IMP hadacidin, NO3-, and Mg2+ [12].

Biological context of purA

• Nucleotide sequence and analysis of the purA gene encoding adenylosuccinate synthetase of Escherichia coli K12 [1].
• The nucleotide sequences of purA and guaA were determined from a series of gene fragments isolated by polymerase chain reaction amplification, library screening, and plasmid rescue techniques [2].
• Comparison of the 5'-flanking regions of purA and guaA with the pur operon suggests similarities in mechanisms for gene regulation [2].
• To examine the effects on replication initiation in B. subtilis, we constructed a strain in which a copy of the dnaA gene was integrated at the purA locus on the chromosome under the control of an isopropyl-beta-D-thiogalactopyranoside (IPTG)-inducible promoter [13].
• Cloning followed by nucleotide sequencing of the vacB region showed it to contain a 2,280-bp open reading frame encoding an 86.9-kDa protein located 669 bp downstream from the 3' end of the open reading frame for the purA gene [14].

Anatomical context of purA

• Escherichia coli K1 purA and sorC are preferentially expressed upon association with human brain microvascular endothelial cells [15].
• Two genes were identified, purA (encodes adenylosuccinate synthetase) and a sorC homologue (encodes a member of the sorC family of transcriptional regulators), whose expression were preferentially induced when bacteria were associated with eukaryotic cells [15].

Associations of purA with chemical compounds

• Introduction of a purR mutation in wild-type and pur-lac fusion strains was found to abolish purine repression of all genes of the purine biosynthetic pathway except for purA [16].
• In purA mutants deprived of adenine, this amount increased sixfold within 2 h [17].
• The cloned E. ictaluri purA gene was mutated by deleting a 598-bp segment of the gene and inserting the kanamycin resistance gene from Tn903 into the gap [3].
• The three substrates of adenylosuccinate synthetase (GTP, IMP, and aspartate) showed different effects in their ability to protect the enzyme against PLP inactivation [10].
• These findings suggest that the glycine-rich sequence in adenylosuccinate synthetase functions differently relative to those in other GTP binding proteins or enzymes [11].

Other interactions of purA

• Suppression of the defects in rdgB mutants of Escherichia coli K-12 by the cloned purA gene [18].

Analytical, diagnostic and therapeutic context of purA

• The size of the purA mRNA was determined by Northern blotting to be approximately 1.5 kilobase pairs [1].
• To determine the role of this sequence in the structure and function of Escherichia coli adenylosuccinate synthetase, site-directed mutagenesis was performed to generate five mutant enzymes: G12V (Gly12----Val), G15V (Gly15----Val), G17V (Gly17----Val), K18R (Lys18----Arg), and I19T (Ile19----Thr) [11].

References