Degradation of 2-Ketoarginine by Guanidinobutyrase in Arginine Aminotransferase Pathway of<i>Brevibacterium helvolum</i>

Yorifuji, Tohru; Kaneoke, Mitsuoki; Okazaki, Takao; Shimizu, Eiichi

doi:10.1271/bbb.59.512

Cited by 3 publications

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“…GBases have been purified and characterized from P. putida P2, Pseudomonas sp. strain ATCC 14676, and Brevibacterium helvolum (4,39,40). Yorifuji et al (41) also purified GBase from P. aeruginosa PAO1, without, however, characterizing this enzyme in detail.…”

Section: Discussionmentioning

confidence: 99%

“…The GbuA enzyme of strain PAO1 purified in this study has essentially the same properties as the GBases of P. putida P2 and Pseudomonas sp. strain ATCC 14676 in terms of substrate specificity, Mn 2ϩ requirement, and high optimum pH (4,39,40). However, the size of the tetrameric PAO1 enzyme (140 kDa) appears to be smaller than that of its hexameric counterparts from P. putida P2 (178 to 190 kDa) (4) and Pseudomonas sp.…”

Section: Discussionmentioning

confidence: 99%

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Characterization and Regulation of the gbuA Gene, Encoding Guanidinobutyrase in the Arginine Dehydrogenase Pathway of Pseudomonas aeruginosa PAO1

Nakada

Itoh

2002

J Bacteriol

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The arginine dehydrogenase (or oxidase) pathway catabolically converts arginine to succinate via 2-ketoglutarate and 4-guanidinobutyrate (4-GB) with the concomitant formation of CO 2 and urea. Guanidinobutyrase (GBase; EC 3.5.3.7) catalyzes the conversion of 4-guanidinobutyrate to 4-aminobutyrate and urea in this pathway. We investigated the structure and regulation of the gene for GBase (designated gbuA) of Pseudomonas aeruginosa PAO1 and characterized the gbuA product. The gbuA and the adjacent gbuR genes were cloned by functional complementation of a gbuA9005 mutant of strain PAO1 defective in 4-GB utilization. The deduced amino acid sequence of GbuA (319 amino acids; M r 34,695) assigned GBase to the arginase/agmatinase family of C-N hydrolases. Purified GbuA was a homotetramer of 140 kDa that catalyzed the specific hydrolysis of 4-GB with K m and K cat values of 49 mM and 1,012 s ؊1, respectively. The divergent gbuR gene, which shared the intergenic promoter region of 206 bp with gbuA, encoded a putative regulatory protein (297 amino acids; M r 33,385) homologous to the LysR family of proteins. Insertional inactivation of gbuR by a gentamicin resistance cassette caused a defect in 4-GB utilization. GBase and gbuA::lacZ fusion assays demonstrated that this gbuR mutation abolishes the inducible expression of gbuA by exogenous 4-GB, indicating that GbuR participates in the regulation of this gene. Northern blotting located an inducible promoter for gbuA in the intergenic region, and primer extension localized the transcription start site of this promoter at 40 bp upstream from the initiation codon of gbuA. The gbuRA genes at the genomic map position of 1547000 are unlinked to the 2-ketoarginine utilization gene kauB at 5983000, indicative of at least two separate genetic units involved in the arginine dehydrogenase pathway.Pseudomonads utilize arginine and related guanidino compounds such as agmatine and 4-guanidinobutyrate (4-GB) as carbon and nitrogen sources (33,35). Four arginine catabolic pathways have been identified in P. aeruginosa PAO1 (6, 9) (Fig. 1). The arginine deiminase (ADI) pathway encoded by the arcDABC operon is induced under anaerobic conditions with an auxiliary induction effect by exogenous arginine (8,9,21). This pathway supports slow anaerobic cell growth of PAO1 by providing ATP from arginine (9) (Fig. 1). The arginine succinyltransferase (AST) pathway (encoded by the aru operon) is a major route of arginine utilization as carbon and nitrogen sources under aerobic conditions (6, 9, 15, 17). Exogenous arginine induces the expression of the aru and aot-argR operons (encoding an arginine/ornithine transport system and the ArgR regulatory protein) through the ArgR function (26, 28). Glutamate, the product of this pathway, is finally channeled into the tricarboxylic acid cycle by catabolic glutamate dehydrogenase, which is coordinately induced by ArgR in the presence of exogenous arginine (20). The arginine decarboxylase (ADC) pathway consists of arginine decarboxylase, agmatine deiminase (a...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%