Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.7 (adenine phosphoribosyltransferase)
 692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell extracts of Acholeplasma laidlawii B-PG9, Acholeplasma morum S2, Mycoplasma capricolum 14, and Mycoplasma gallisepticum S6 were examined for 37 cytoplasmic enzyme activities involved in the salvage and biosynthesis of purines. All of these organisms had adenine phosphoribosyltransferase activity (EC 2.4.2.7) and hypoxanthine phosphoribosyltransferase activity (EC 2.4.2.8). All of these organisms had purine-nucleoside phosphorylase activity (EC 2.4.2.1) in the synthetic direction using ribose-1-phosphate (R-1-P) or deoxyribose-1-phosphate (dR-1-P); this activity generated ribonucleosides or deoxyribonucleosides, respectively. The pyrimidine nucleobase uracil could also be ribosylated by using either R-1-P or dR-1-P as a donor. The synthesis of deoxyribonucleosides from nucleobases and dR-1-P has been reported from only one other procaryote, Escherichia coli (L. A. Mason and J. O. Lampen, J. Biol. Chem. 193:539-547, 1951). The reverse of this phosphorylase reaction is more widely known, and we found such activity in all mollicutes studied. Some Acholeplasma species but not the Mycoplasma species can phosphorylate deoxyribonucleosides to deoxyribomononucleotides by a PPi-dependent deoxyribonucleoside kinase activity, which was first reported in this group for the ribose analogs (V. V. Tryon and J. D. Pollack, Int. J. Syst. Bacteriol. 35:497-501, 1985). This is the first report of PPi-dependent purine deoxyribonucleoside kinase activity. An ATP-dependent purine deoxyribonucleoside kinase activity is known only in salmon milt extracts (H. L. A. Tarr, Can. J. Biochem. 42:1535-1545, 1964). Deoxyribomononucleotidase activity was also found in cytoplasmic extracts of these mollicutes. This is the first report of deoxyribomononucleotidase activity.
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PMID:Synthesis of deoxyribomononucleotides in Mollicutes: dependence on deoxyribose-1-phosphate and PPi. 303 46

A 0.972-kilobase pair DNA fragment from Streptomyces lividans that induces the production of the blue-pigmented antibiotic actinorhodine in S. lividans when cloned on a multicopy plasmid has led to the isolation of a 4-kilobase pair DNA fragment from Streptomyces coelicolor containing homologous sequence. Computer-assisted analysis of the DNA sequence revealed three putative open reading frames (ORFs), ORF1, ORF2, and ORF3. ORF2 extends beyond the sequenced DNA fragment, and its deduced product shares no similarities with any other known proteins in the data bases. ORF3 is also truncated, and its 41-amino acid C-terminal product is identical to the S. coelicolor adenine phosphoribosyltransferase. The 847-amino acid ORF1 protein, with a predicted molecular mass of 94.2 kDa, strongly resembled the relA and spoT gene products from Escherichia coli and the homologs from Vibrio sp. strain S14, Haemophilus influenzae, Streptococcus equisimilis H46A, and Mycoplasma genitalium. Unlike these proteins, the ORF1 amino acid sequence analysis revealed the presence of a putative ATP/GTP-binding domain. A mutant was generated by deleting most of the ORF1 gene that showed an actinorhodine-nonproducing phenotype, while undecylprodigiosin and the calcium-dependent antibiotic were unaffected. The mutant strain grew at a much lower rate than the wild-type strain, and spore formation was delayed. When the gene was propagated on a low copy number vector, not only was actinorhodine production restored, but actinorhodine and undecylprodigiosin production was enhanced in both the mutant and wild-type and morphological differentiation returned to wild-type characteristics. (p)ppGpp synthetase activity was not detected in purified ribosomes from the ORF1-deleted mutant, while it was restored by complementation of this strain.
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PMID:A relA/spoT homologous gene from Streptomyces coelicolor A3(2) controls antibiotic biosynthetic genes. 863 67