Metabolic pathway for the utilization of L-arginine, L-ornithine, agmatine, and putrescine as nitrogen sources in Escherichia coli K-12

Abstract

The pathway for the utilization of L-arginine, agmatine, L-ornithine, and putrescine as the sole nitrogen source by Escherichia coli K-12 has been elucidated. Mutants impaired in the utilization of one or more of the above compounds were isolated, and their growth on the different compounds as a sole source of nitrogen and the activities of enzymes of the putative pathway were examined. Our results show that L-arginine is first decarboxylated to agmatine, which is hydrolyzed to urea and putrescine. L-Ornithine is decarboxylated to putrescine. Putrescine is transaminated to y-aminobutyraldehyde, which is oxidized to y-aminobutyric acid.-y-Aminobutyric acid is degraded to succinate.

Enzymes and pathways of polyamine breakdown in microorganisms

“…Putrescine breakdown in Escherichia coli (Fig. 2) has been well documented both genetically [14,15] and biochemically [10].…”

“…The positions of the genes encoding two key enzymes of the non-acetylated route of putreseine breakdown (see Fig. 2) were mapped by Shaibe et al [14] and the diamine aminotransferase (pat) and Al-pyrrofin¢ dehydrogenase (prr) genes were located at 89 and 30 rain respectively on the Escherich~a coli K-12 chromosome. Mutants defective in either of these enzymes had growth yield~ for putrescine of only about 10% of the wild-type and had about 10% residual enzyme activity [14].…”

“…2) were mapped by Shaibe et al [14] and the diamine aminotransferase (pat) and Al-pyrrofin¢ dehydrogenase (prr) genes were located at 89 and 30 rain respectively on the Escherich~a coli K-12 chromosome. Mutants defective in either of these enzymes had growth yield~ for putrescine of only about 10% of the wild-type and had about 10% residual enzyme activity [14]. In addition to being involved in polyamine breakdown, this pathway is also used in Escherichia coli for the breakdown of arginine, agmatine and ornithine (Fig.…”

DcuA of aerobically grown Escherichia coli serves as a nitrogen shuttle (L‐aspartate/fumarate) for nitrogen uptake

“…Fumarate and NH 3 rate are released from L-aspartate by the function of aspartase (AspA; main pathway, black). A minor route (presented in gray) uses the Krebs-Henseleit and the arginine succinyl-transferase (AST) pathway for release of fumarate and NH 3 (Shaibe et al, 1985;Goux et al, 1995). Ammonia released by AspA, but also from the AST route represents the source for ammonia assimilation (Shaibe et al, 1985;Goux et al, 1995).…”

“…A minor route (presented in gray) uses the Krebs-Henseleit and the arginine succinyl-transferase (AST) pathway for release of fumarate and NH 3 (Shaibe et al, 1985;Goux et al, 1995). Ammonia released by AspA, but also from the AST route represents the source for ammonia assimilation (Shaibe et al, 1985;Goux et al, 1995). The fumarate produced by either the AspA or the AspA independent route (Krebs-Henseleit/AST reactions) is excreted by DcuA as shown in the present study.…”