The control of pyrimidine nucleotide formation in the bacterium Pseudomonas aurantiaca ATCC 33663 by pyrimidines was studied. The activities of the pyrimidine biosynthetic pathway enzymes were investigated in P. aurantiaca ATCC 33663 cells and from cells of an auxotroph lacking orotate phosphoribosyltransferase activity under selected culture conditions. All activities of the pyrimidine biosynthetic pathway enzymes in ATCC 33663 cells were depressed by uracil addition to the minimal medium when succinate served as the carbon source. In contrast, all pyrimidine biosynthetic pathway enzyme activities in ATCC 33663 cells were depressed by orotic acid supplementation to the minimal medium when glucose served as the carbon source. The orotidine 5′-monophosphate decarboxylase activity in the phosphoribosyltransferase mutant strain increased by more than sixfold in succinate-grown cells and by more than 16-fold in glucose-grown cells after pyrimidine limitation showing possible repression of the decarboxylase by a pyrimidine-related compound. Inhibition by ATP, GTP, UTP and pyrophosphate of the in vitro activity of aspartate transcarbamoylase in ATCC 33663 was observed. The findings demonstrated control at the level of pyrimidine biosynthetic enzyme synthesis and activity for the P. aurantiaca transcarbamoylase. The control of pyrimidine synthesis in P. aurantiaca seemed to differ from what has been observed previously for the regulation of pyrimidine biosynthesis in related Pseudomonas species. This investigation could prove helpful to future work studying pseudomonad taxonomic analysis as well as to those exploring antifungal and antimicrobial agents produced by P. aurantiaca.

中文翻译：

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控制橙黄色假单胞菌中嘧啶核苷酸的形成

研究了嘧啶对橙子假单胞菌 ATCC 33663 中嘧啶核苷酸形成的控制。在 P. aurantiaca ATCC 33663 细胞和在选定的培养条件下缺乏乳清酸磷酸核糖基转移酶活性的营养缺陷型细胞中研究了嘧啶生物合成途径酶的活性。当琥珀酸作为碳源时，在基本培养基中添加尿嘧啶会抑制 ATCC 33663 细胞中嘧啶生物合成途径酶的所有活性。相比之下，当葡萄糖作为碳源时，ATCC 33663 细胞中的所有嘧啶生物合成途径酶活性都被基本培养基中的乳清酸补充所抑制。在嘧啶限制后，磷酸核糖基转移酶突变株中的乳清酸 5'-单磷酸脱羧酶活性在琥珀酸生长细胞中增加了 6 倍以上，在葡萄糖生长细胞中增加了 16 倍以上，表明嘧啶相关化合物可能抑制脱羧酶. 观察到 ATP、GTP、UTP 和焦磷酸盐对 ATCC 33663 中天冬氨酸转氨甲酰酶的体外活性的抑制作用。研究结果证明了在嘧啶生物合成酶合成水平上的控制以及对橙皮霉转氨甲酰酶的活性的控制。P. aurantiaca 中嘧啶合成的控制似乎与之前观察到的相关假单胞菌物种中嘧啶生物合成的调控不同。