Flint H J, Dible S, Kacser H
J Gen Microbiol. 1985 Nov;131(11):2891-900. doi: 10.1099/00221287-131-11-2891.
Ornithine carbamoyltransferase and argininosuccinase, two enzymes involved in arginine synthesis, are regulated by cross-pathway amino acid control in Neurospora and show derepression in response to limitation of any one of a number of amino acids. The effects of varying the severity of arginine limitation upon the synthesis of these enzymes, in mycelial cultures of an arginine auxotrophic strain, are reported here. Depression occurred at arginine concentrations sufficient to allow normal rates of protein accumulation, leading to increases of not more than fourfold in the absolute rate of enzyme synthesis. On the other hand, differential rates of enzyme synthesis increased progressively up to 20-fold or more under extreme conditions of arginine limitation that also limit net protein synthesis. The major part of the derepression response thus occurred at arginine concentrations that allowed low net rates of protein synthesis. The physiological significance of this is not yet understood. Our evidence suggests that these responses were mediated entirely through the cross-pathway control system, and may not be untypical (allowing for variations in magnitude) of depression resulting through this mechanism in Neurospora.
鸟氨酸氨甲酰基转移酶和精氨琥珀酸酶是参与精氨酸合成的两种酶，在粗糙脉孢菌中受交叉途径氨基酸控制的调节，并且在多种氨基酸中的任何一种受到限制时会表现出阻遏解除。本文报道了在精氨酸营养缺陷型菌株的菌丝体培养物中，改变精氨酸限制的严重程度对这些酶合成的影响。在足以使蛋白质积累达到正常速率的精氨酸浓度下出现了抑制作用，导致酶合成的绝对速率增加不超过四倍。另一方面，在同样限制净蛋白质合成的极端精氨酸限制条件下，酶合成的差异速率逐渐增加至20倍或更多。因此，阻遏解除反应的主要部分发生在允许低净蛋白质合成速率的精氨酸浓度下。其生理意义尚不清楚。我们的证据表明，这些反应完全是通过交叉途径控制系统介导的，并且对于粗糙脉孢菌中通过这种机制导致的抑制作用（考虑到幅度的变化）可能并非不典型。
