title: Analysis of the relA gene product of Escherichia coli.
abstract: The relA gene product, ATP: GTP 3'-pyrophosphotransferase (stringent factor) has been isolated in homogeneous form from an Escherichia coli strain polyploid for this gene at a yield of 1 mg/100 g cells and at a specific activity in a ribosome-activated assay at 37 degrees C of 120 mumol guanosine pentaphosphate formed min-1 mg protein-1. The specific activity in a methanol-activated assay at 25 degrees C was found to be 4 mumol guanosine pentaphosphate formed min-1 mg protein-1. These values are about 100 times higher than reported by others. Our further studies of this enzyme led to the following results. Antibodies raised against this enzyme inhibit the ribosome-activated synthesis of guanosine tetraphosphate and pentaphosphate but have no effect on the much slower synthesis, detected in the absence of ribosomes. The amount of stringent factor in the relA+ strain CP78 is estimated to about 1 copy per 200 ribosomes. The amount of antibody-binding material in CP79 (relA) is at least 5 times lower.
mesh_terms: D000907:Antibodies, Bacterial; D000917:Antibody Formation; D001666:Binding Sites, Antibody; D004355:Drug Stability; D004926:Escherichia coli / Q000201:enzymology*; D005796:Genes; D006150:Guanine Nucleotides / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D010756:Phosphoric Acids; D010770:Phosphotransferases / Q000302:isolation & purification* / Q000378:metabolism; D011123:Polyploidy; D011233:Precipitin Tests; D012269:Ribosomal Proteins / Q000302:isolation & purification*; D013045:Species Specificity
chemical_list: D000907:Antibodies, Bacterial; D006150:Guanine Nucleotides; D010756:Phosphoric Acids; D012269:Ribosomal Proteins; D006160:Guanosine Triphosphate; D010770:Phosphotransferases