Metabolism of L-Arginine, Agmatine, and Related Compounds in Nocardioides simplex

Abstract

Nocardioides simplex IFO 12069 (Arthrobacter simplex ATCC 6946) was examined for the degradation of L-ornithine, L-citrulline, L-arginine, D-arginine, agmatine, carbamoylputrescine, and putrescine, and the results were compared with those obtained in a previous study with A. globiformis and Brevibacterium helvolum. D-Arginine as well as L-arginine was degraded via the arginine oxygenase pathway. A part of L-citrulline was probably degraded via the pathway. The L-ornithine degradation via the pathway was obscure. Guanidinobutyrase was induced by agmatine, which was shown to be degraded via a unique pathway. The first step of the pathway converted agmatine to 4-guanidinobutyraldehyde by transferring the amino group to pyruvate. The second step was the NAD-linked dehydrogenation of the aldehyde to 4-guanidinobutyrate, which was then degraded to 4-aminobutyrate. The enzymes for the first and second steps were identified as diaminopropane aminotransferase (EC 2. 6. 1. -) and aminobutyraldehyde dehydrogenase (EC 1. 2. 1. 19), respectively. These enzymes also degraded putrescine to 4-aminobutyrate. Carbamoylputrescine was converted by the aminotransferase to the corresponding aldehyde, which was accumulated in the medium.