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PMID:16585758
Citation |
Morizono, H, Cabrera-Luque, J, Shi, D, Gallegos, R, Yamaguchi, S, Yu, X, Allewell, NM, Malamy, MH and Tuchman, M (2006) Acetylornithine transcarbamylase: a novel enzyme in arginine biosynthesis. J. Bacteriol. 188:2974-82 |
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Abstract |
Ornithine transcarbamylase is a highly conserved enzyme in arginine biosynthesis and the urea cycle. In Xanthomonas campestris, the protein annotated as ornithine transcarbamylase, and encoded by the argF gene, is unable to synthesize citrulline directly from ornithine. We cloned and overexpressed this X. campestris gene in Escherichia coli and show that it catalyzes the formation of N-acetyl-L-citrulline from N-acetyl-L-ornithine and carbamyl phosphate. We now designate this enzyme as an acetylornithine transcarbamylase. The K(m) values for N-acetylornithine and carbamyl phosphate were 1.05 mM and 0.01 mM, respectively. Additional putative transcarbamylases that might also be misannotated were found in the genomes of members of other xanthomonads, Cytophaga, and Bacteroidetes as well as in DNA sequences of bacteria from environmental isolates. It appears that these different paths for arginine biosynthesis arose very early in evolution and that the canonical ornithine transcarbamylase-dependent pathway became the prevalent form. A potent inhibitor, N(alpha)-acetyl-N(delta)-phosphonoacetyl-L-ornithine, was synthesized and showed a midpoint of inhibition at approximately 22 nM; this compound may prove to be a useful starting point for designing inhibitors specific to this novel family of transcarbamylases. |
Links |
PubMed PMC1446984 Online version:10.1128/JB.188.8.2974-2982.2006 |
Keywords |
Arginine/biosynthesis; Bacteroidetes/genetics; Carbamyl Phosphate/metabolism; Carboxyl and Carbamoyl Transferases/antagonists & inhibitors; Carboxyl and Carbamoyl Transferases/genetics; Carboxyl and Carbamoyl Transferases/isolation & purification; Carboxyl and Carbamoyl Transferases/metabolism; Cloning, Molecular; Cytophaga/genetics; Enzyme Inhibitors/chemical synthesis; Enzyme Inhibitors/pharmacology; Escherichia coli/genetics; Gene Expression; Genome, Bacterial/genetics; Mass Spectrometry; Molecular Structure; Ornithine/analogs & derivatives; Ornithine/metabolism; Xanthomonas campestris/enzymology |
edit table |
Significance
Annotations
Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
---|---|---|---|---|---|---|---|---|
GO:0043857: N-acetylornithine carbamoyltransferase activity |
ECO:0000314: |
F |
Table 1: Purified ArgF′ enzyme from Xanthomonas catalyzed the AOTCase reaction which forms N-acetylcitrulline from N-acetylornithine and carbamyl phosphate. Figure 4: LC-MS analysis of enzymatically synthesized N-acetylcitrulline. The enzymatic product of the X. campestris AOTCase reaction has the same mass ion and retention time as chemically synthesized N-acetylcitrulline. |
complete | ||||
enables |
GO:0043857: N-acetylornithine carbamoyltransferase activity |
ECO:0000314: direct assay evidence used in manual assertion |
F |
Seeded From UniProt |
complete | |||
See also
References
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