The purB gene of Escherichia coli K-12 is located in an operon.
The structural gene (purB) for succinyl-AMP (S-AMP) lyase and three additional ORFs are on the same DNA strand of the chromosome of Escherichia coli. Cassette mutagenesis and primer extension mapping demonstrated that purB is co-transcribed with an upstream gene (ORF23, or ycfC) encoding a 22.9 kDa membrane-associated protein of non-essential, but unknown, function unrelated to purine biosynthesis. The purB operon lies between phoP and an ORF expressing an essential function which may correspond to asuE (trmU). S-AMP lyase was purified to near homogeneity. The purified enzyme is a homotetramer of 50 kDa subunits, has a K(m) for S-AMP of 3.7 microM and a pH optimum of 7.4-7.6.
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Department of Biochemistry, University of Southampton, Crescent East, UK.
Malik
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Giles
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Drabble
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D000264:Adenylosuccinate Lyase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation; D016366:Open Reading Frames; D009876:Operon; D011487:Protein Conformation; D015183:Restriction Mapping; D015398:Signal Transduction; D014158:Transcription, Genetic
D017931:DNA Primers; D004269:DNA, Bacterial; D000264:Adenylosuccinate Lyase