Function of a glutathione-dependent formaldehyde dehydrogenase in Rhodobacter sphaeroides formaldehyde oxidation and assimilation
Function of a glutathione-dependent formaldehyde dehydrogenase in Rhodobacter sphaeroides formaldehyde oxidation and assimilation
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DOI：
10.1021/bi971463t
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发表时间：
1998-01-13
期刊：
影响因子：
2.9
通讯作者：
Donohue, TJ
中科院分区：
文献类型：
--
作者：
Barber, RD;Donohue, TJ
尽管甲醛与许多生物分子具有反应性，但几乎所有细胞都能遇到甲醛。谷胱甘肽依赖性甲醛脱氢酶（GSH-FDH）在原核生物和真核生物中广泛存在，表明该酶在生物甲醛氧化中起着重要和普遍的作用。这项工作旨在确定GSH-FDH在兼性光养细菌球形红细菌中的作用。野生型和突变体细胞的生长表型，酶比活性的变化，和C-13标记的化合物的NMR光谱检测模式累积表明，R。GSH-FDH在光合和有氧呼吸条件下的甲醛代谢中起关键作用。在光合作用细胞中，数据表明GSH-FDH以NADH的形式产生还原力，以及被Calvin-Benson-Bassham循环氧化为二氧化碳的一碳骨架。例如，使用甲醇作为唯一的光合作用碳源增加了GSH-FDH（NAD依赖性甲酸脱氢酶）和关键的Calvin-Benson-Bassham循环酶（核酮糖-1，5-二磷酸羧化酶）的比活性。[C-13]甲醛氧化产物在光合作用细胞中积累的模式以及确定的GSH-FDH或卡尔文循环突变体不能使用甲醇作为唯一碳源也支持GSH-FDH的这种作用。我们的数据还表明，GSH-FDH的行为在甲醛异化时，有氧呼吸培养共代谢甲醇和琥珀酸。
Despite its reactivity with many biological molecules, formaldehyde can be commonly encountered by virtually all cells. The widespread existence of glutathione-dependent formaldehyde dehydrogenases (GSH-FDH) in procaryotes and eucaryotes suggests this enzyme plays a central and universal role in biological formaldehyde oxidation. This work sought to determine the role of GSH-FDH in the facultative phototrophic bacterium Rhodobacter sphaeroides. Growth phenotypes of wild type and mutant cells, changes in enzyme specific activities, and the pattern of C-13-labeled compounds detected by NMR spectroscopy cumulatively suggest that R. sphaeroides GSH-FDH can play a critical role in formaldehyde metabolism under both photosynthetic and aerobic respiratory conditions. In photosynthetic cells, the data indicate that GSH-FDH generates reducing power, in the form of NADH, and one-carbon skeletons that are oxidized to carbon dioxide for subsequent assimilation by the Calvin-Benson-Bassham cycle. For example, use of methanol as a sole photosynthetic carbon source increases the specific activities of GSH-FDH, an NAD-dependent formate dehydrogenase, and the key Calvin-Benson-Bassham cycle enzyme, ribulose-1,5-bisphosphate carboxylase. This role of GSH-FDH is also supported by the pattern of [C-13]formaldehyde oxidation products that accumulate in photosynthetic cells and the inability of defined GSH-FDH or Calvin cycle mutants to use methanol as a sole carbon source. Our data also suggest that GSH-FDH acts in formaldehyde dissimilation when aerobic respiratory cultures cometabolize methanol and succinate.