Department of Plant Pathology, University of California, Berkeley, CA 94720, USA.
EMBO J. 1987 Dec 1;6(12):3585-91. doi: 10.1002/j.1460-2075.1987.tb02689.x.
Two different DNA fragments encoding ornithine carbamoyltransferase (OCTase) were cloned from Pseudomonas syringae pv. phaseolicola NPS3121. These fragments did not cross-hybridize and encoded OCTases which differed with respect to their sensitivity to purified phaseolotoxin, an OCTase inhibitor produced by this phytopathogenic bacterium. Recombinant plasmids carrying these DNA fragments complemented OCTase-deficient strains of Escherichia coli and Pseudomonas aeruginosa. Extracts of the complemented E. coli strain contained OCTase enzyme activities with similar degrees of sensitivity to purified phaseolotoxin as extracts of P.s.phaseolicola grown at either 20 or 30 degrees C. The OCTase activity detectable in extracts of P.s.phaseolicola grown at 20 degrees C is insensitive to phaseolotoxin while that detectable in extracts of cells grown at 30 degrees C is sensitive to the toxin. E.coli HB101 harboring recombinant plasmids carrying the gene(s) encoding the phaseolotoxin-insensitive enzyme activity exhibited resistance to purified phaseolotoxin. The results of Tn5 mutagenesis and Southern blotting and the pattern of complementation of OCTase-deficient and Tox mutant strains suggest that the gene(s) encoding the phaseolotoxin-insensitive OCTase is part of a gene cluster involved in phaseolotoxin production.
从丁香假单胞菌 pv. phaseolicola NPS3121 中克隆了两个不同的编码鸟氨酸氨甲酰转移酶 (OCTase) 的 DNA 片段。这些片段不发生交叉杂交，并且编码的 OCTase 对纯化的菜豆毒素（一种由这种植物病原菌产生的 OCTase 抑制剂）的敏感性不同。携带这些 DNA 片段的重组质粒互补了大肠杆菌和铜绿假单胞菌中 OCTase 缺陷型菌株。互补大肠杆菌菌株提取物中的 OCTase 酶活性对纯化的菜豆毒素的敏感性与 P.s.phaseolicola 在 20 或 30°C 生长时的提取物相似。在 20°C 下生长的 P.s.phaseolicola 提取物中可检测到的 OCTase 活性对菜豆毒素不敏感，而在 30°C 下生长的细胞提取物中的 OCTase 活性对毒素敏感。携带编码对菜豆毒素不敏感的酶活性的基因的重组质粒的大肠杆菌 HB101 表现出对纯化的菜豆毒素的抗性。Tn5 诱变和 Southern 印迹的结果以及 OCTase 缺陷型和 Tox 突变型菌株的互补模式表明，编码对菜豆毒素不敏感的 OCTase 的基因是参与菜豆毒素产生的基因簇的一部分。
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