Fig. 1

The metabolic map of putrescine in E. coli K-12. The Xs indicate the knocked out genes. Thick arrows indicate the overexpression of genes. Dash arrows indicate the increased expression of genes. Blunt end arrows indicate inhibition of the expression of genes. GdhA glutamate dehydrogenase, HdfR DNA-binding transcriptional dual regulator HdfR, GltBD glutamate synthase, GlnA glutamine synthetase, GlnE glutamine synthetase adenylyltransferase, CarAB carbamoyl phosphate synthetase, ArgA N-acetylglutamate synthase, ArgB acetylglutamate kinase, ArgC N-acetylglutamylphosphate reductase, ArgD N-acetylornithine aminotransferase, ArgE acetylornithine deacetylase, ArgF ornithine carbamoyltransferase, ArgI ornithine carbamoyltransferase, ArgG argininosuccinate synthetase, ArgH argininosuccinate lyase, ArgR DNA-binding transcriptional dual regulator ArgR, SpeA biosynthetic arginine decarboxylase, SpeB agmatinase, SpeC constitutive ornithine decarboxylase, SpeD S-adenosylmethionine decarboxylase, SpeE spermidine synthase, SpeF inducible ornithine decarboxylase, SpeG spermidine N-acetyltransferase, PatA putrescine aminotransferase, PatD γ-aminobutyraldehyde dehydrogenase, GabT 4-aminobutyrate aminotransferase, GabD succinate-semialdehyde dehydrogenase GabD, Sad succinate-semialdehyde dehydrogenase Sad, PuuA glutamate-putrescine ligase, PuuB γ-glutamylputrescine oxidase, PuuC γ-glutamyl-γ-aminobutyraldehyde dehydrogenase, PuuD γ-glutamyl-γ-aminobutyrate hydrolase, PuuP putrescine importer, YdcSTUV putrescine importer, PotFGHI putrescine importer, PlaP putrescine importer, PotE putrescine-ornithine antiporter/putrescine importer, SapBCDF putrescine exporter, TCA cycle tricarboxylic acid cycle