Department of Plant & Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA, 94720, USA.
Department of Biosciences, University of Oslo, Blindern, Box 1066, 0316, Oslo, Norway.
Photosynth Res. 2017 Nov;134(2):117-131. doi: 10.1007/s11120-017-0429-0. Epub 2017 Oct 10.
For the first decade following its description in 1954, the Calvin-Benson cycle was considered the sole pathway of autotrophic CO assimilation. In the early 1960s, experiments with fermentative bacteria uncovered reactions that challenged this concept. Ferredoxin was found to donate electrons directly for the reductive fixation of CO into alpha-keto acids via reactions considered irreversible. Thus, pyruvate and alpha-ketoglutarate could be synthesized from CO, reduced ferredoxin and acetyl-CoA or succinyl-CoA, respectively. This work opened the door to the discovery that reduced ferredoxin could drive the Krebs citric acid cycle in reverse, converting the pathway from its historical role in carbohydrate breakdown to one fixing CO. Originally uncovered in photosynthetic green sulfur bacteria, the Arnon-Buchanan cycle has since been divorced from light and shown to function in a variety of anaerobic chemoautotrophs. In this retrospective, colleagues who worked on the cycle at its inception in 1966 and those presently working in the field trace its development from a controversial reception to its present-day inclusion in textbooks. This pathway is now well established in major groups of chemoautotrophic bacteria, instead of the Calvin-Benson cycle, and is increasingly referred to as the Arnon-Buchanan cycle. In this retrospective, separate sections have been written by the authors indicated. Bob Buchanan wrote the abstract and the concluding comments.
在 1954 年被描述后的第一个十年里，卡尔文-本森循环被认为是自养 CO 同化的唯一途径。在 20 世纪 60 年代，对发酵细菌的实验发现了挑战这一概念的反应。发现铁氧还蛋白可以直接将电子供体用于通过被认为是不可逆的反应将 CO 还原固定为α-酮酸。因此，分别可以从 CO、还原型铁氧还蛋白和乙酰辅酶 A 或琥珀酰辅酶 A 合成丙酮酸和α-酮戊二酸。这项工作为发现还原型铁氧还蛋白可以驱动克雷布斯柠檬酸循环反向，将该途径从其在碳水化合物分解中的历史作用转变为固定 CO 的作用打开了大门。最初在光合作用的绿硫细菌中发现的 Arnon-Buchanan 循环已经与光分离，并在各种厌氧化能自养生物中显示出功能。在这篇回顾中，1966 年开始研究该循环的同事和目前在该领域工作的同事追溯了它从有争议的接受到现在被纳入教科书的发展过程。这条途径现在已经在化能自养细菌的主要群体中确立，而不是卡尔文-本森循环，并且越来越多地被称为 Arnon-Buchanan 循环。在这篇回顾中，由指定的作者撰写了单独的章节。Bob Buchanan 撰写了摘要和结论性评论。
