Quay S C, Friedman S B, Eisenberg R C
J Bacteriol. 1972 Oct;112(1):291-8. doi: 10.1128/jb.112.1.291-298.1972.
Induction of Entner-Doudoroff pathway enzymes in Pseudomonas fluorescens was investigated to study the role of gluconate as a possible inducer. Glucose oxidase-deficient mutants were isolated and characterized. One of these mutants, gox-7, was deficient in particulate glucose oxidase; another mutant, gox-17, was deficient in particulate glucose and gluconate oxidase activities. Gluconate, but not glucose, induced synthesis of gluconokinase and 6-phosphogluconate dehydratase in both mutants. High constitutive levels of 2-keto-3-deoxy-6-phosphogluconate aldolase were found when both mutants were grown on glucose. Growth of parent and both mutant strains on glycerol also resulted in high levels of Entner-Doudoroff pathway enzymes. It was concluded that glucose cannot serve as an inducer molecule for derepression of Entner-Doudoroff pathway enzymes in P. fluorescens. Evidence presented provides good support for gluconate being the true inducer of this pathway in P. fluorescens. A relationship is presented for explaining distribution of the Entner-Doudoroff pathway in certain groups of bacteria.
为了研究葡萄糖酸盐作为可能诱导剂的作用，对荧光假单胞菌中Entner-Doudoroff途径酶的诱导情况进行了研究。分离并鉴定了葡萄糖氧化酶缺陷型突变体。其中一个突变体gox-7缺乏颗粒状葡萄糖氧化酶；另一个突变体gox-17缺乏颗粒状葡萄糖和葡萄糖酸盐氧化酶活性。在这两个突变体中，葡萄糖酸盐而非葡萄糖诱导了葡萄糖激酶和6-磷酸葡萄糖酸脱水酶的合成。当两个突变体在葡萄糖上生长时，发现2-酮-3-脱氧-6-磷酸葡萄糖酸醛缩酶的组成型水平很高。亲本菌株和两个突变菌株在甘油上生长也导致Entner-Doudoroff途径酶的高水平表达。得出的结论是，葡萄糖不能作为荧光假单胞菌中Entner-Doudoroff途径酶去阻遏的诱导分子。所提供的证据有力支持了葡萄糖酸盐是荧光假单胞菌中该途径真正诱导剂的观点。提出了一种关系来解释Entner-Doudoroff途径在某些细菌群体中的分布情况。
