Department of Agronomy, University of Illinois, Urbana, Illinois 61801.
Plant Physiol. 1985 Apr;77(4):851-6. doi: 10.1104/pp.77.4.851.
Leaf photosynthesis and ribulose bisphosphate carboxylase activation level were inhibited in several mutants of the C(3) crucifer Arabidopsis thaliana which possess lesions in the photorespiratory pathway. This inhibition occurred when leaves were illuminated under a photorespiratory atmosphere (50% O(2), 350 microliters per liter CO(2), balance N(2)), but not in nonphotorespiratory conditions (2% O(2), 350 microliters per liter CO(2), balance N(2)). Inhibition of carboxylase activation level was observed in strains with deficient glycine decarboxylase, serine transhydroxymethylase, serine-glyoxylate aminotransferase, glutamate synthase, and chloroplast dicarboxylate transport activities, but inhibition did not occur in a glycolate-P phosphatase-deficient strain. Also, the photorespiration inhibitor aminoacetonitrile produced a decline in leaf and protoplast ribulose bisphosphate carboxylase activation level, but was without effect on intact chloroplasts. Fructose bisphosphatase, a light-activated enzyme which is strongly dependent on stromal pH and Mg(2+) for regulation, was unaffected by conditions which caused inhibition of ribulose bisphosphate carboxylase. Thus, the mechanism of inhibition does not appear to involve changes in stromal Mg(2+) and pH but rather is associated with metabolite flux through the photorespiratory pathway.
在几种 C(3)十字花科拟南芥突变体中，光合作用和核酮糖二磷酸羧化酶激活水平受到抑制，这些突变体在光呼吸途径中存在缺陷。当叶片在光呼吸气氛（50% O(2)、350 微升/升 CO(2)、平衡 N(2))下被照射时，会发生这种抑制，但在非光呼吸条件（2% O(2)、350 微升/升 CO(2)、平衡 N(2))下不会发生。在缺乏甘氨酸脱羧酶、丝氨酸羟甲基转移酶、丝氨酸-乙醛酸氨基转移酶、谷氨酸合酶和叶绿体二羧酸转运活性的菌株中观察到羧化酶激活水平的抑制，但在缺乏乙醛酸-P 磷酸酶的菌株中没有抑制发生。此外，光呼吸抑制剂氨基乙腈会导致叶片和原生质体核酮糖二磷酸羧化酶激活水平下降，但对完整叶绿体没有影响。果糖二磷酸酶是一种光激活酶，强烈依赖于基质 pH 和 Mg(2+)进行调节，它不受导致核酮糖二磷酸羧化酶抑制的条件影响。因此，抑制机制似乎不涉及基质 Mg(2+)和 pH 的变化，而是与光呼吸途径中的代谢物通量有关。
