West T P
Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD, USA.
Lett Appl Microbiol. 2004;38(2):81-6. doi: 10.1111/j.1472-765x.2003.01453.x.
To study the regulation of de novo pyrimidine biosynthesis in the pathogenic bacterium Pseudomonas reptilivora ATCC 14836.
The pyrimidine biosynthetic pathway enzymes were assayed in extracts of Ps. reptilivora ATCC 14836 cells and of cells from an auxotroph lacking aspartate transcarbamoylase activity. Pyrimidine biosynthetic pathway enzyme activities in ATCC 14836 were influenced by the addition of pyrimidine bases to the culture medium with orotic acid addition inducing dihydroorotase activity. Pyrimidine starvation of the transcarbamoylase mutant strain increased its de novo enzyme activities suggesting that the de novo pathway was also subject to repression by a pyrimidine-related compound. Aspartate transcarbamoylase activity in ATCC 14836 was inhibited in vitro by pyrophosphate and ATP.
Regulation of pyrimidine biosynthesis in Ps. reptilivora was observed at the level of enzyme synthesis and at the level of activity for aspartate transcarbamoylase. Its regulation of enzyme synthesis seemed to be more highly controlled than what was observed in the related species Ps. fluorescens.
This investigation found that pyrimidine biosynthesis is controlled in Ps. reptilivora. This could prove helpful to future studies exploring its pathogenicity.
研究致病性细菌爬行类假单胞菌ATCC 14836中嘧啶从头合成的调控机制。
对爬行类假单胞菌ATCC 14836细胞提取物以及缺乏天冬氨酸转氨甲酰酶活性的营养缺陷型细胞提取物中的嘧啶生物合成途径酶进行了测定。在培养基中添加嘧啶碱基会影响ATCC 14836中嘧啶生物合成途径的酶活性，添加乳清酸可诱导二氢乳清酸酶活性。转氨甲酰酶突变株的嘧啶饥饿增加了其从头合成酶的活性，这表明从头合成途径也受到嘧啶相关化合物的抑制。在体外，焦磷酸和ATP可抑制ATCC 14836中天冬氨酸转氨甲酰酶的活性。
观察到爬行类假单胞菌中嘧啶生物合成在酶合成水平和天冬氨酸转氨甲酰酶活性水平上受到调控。其酶合成的调控似乎比在相关物种荧光假单胞菌中观察到的更为严格。
本研究发现嘧啶生物合成在爬行类假单胞菌中受到控制。这可能对未来探索其致病性的研究有所帮助。
