@article{mbs:/content/journal/micro/10.1099/13500872-142-11-3219, author = "Green, Stephen M. and Malik, Tahir and Giles, Ian G. and Drabble, William T.", title = "The purB gene of Escherichia coli K-12 is located in an operon", journal= "Microbiology", year = "1996", volume = "142", number = "11", pages = "3219-3230", doi = "https://doi.org/10.1099/13500872-142-11-3219", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-142-11-3219", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "internal promoter", keywords = "Escherichia coli", keywords = "succinyl-AMP lyase", keywords = "phoP gene", keywords = "purB gene", abstract = "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 μM and a pH optimum of 7·4–7·6.", }