Revisiting RuBisCO.

Since the discovery of its role in the CO2 fixation reaction in photosynthesis, RuBisCO has been one of the most extensively researched enzymes in the fields of biochemistry, molecular biology, and molecular genetics as well as conventional plant physiology, agricultural chemistry, and crop science. In addition, the RuBisCO and RuBisCO-like genes of more than 2000 organisms have been sequenced during the past 20 years. During the course of those studies, the origin of the RuBisCO gene began to be discussed. Recent studies have reported that the RuBisCO gene emerged in methanogenic bacteria long before photosynthetic organisms appeared. The origin of similar early genes might have allowed this gene to overcome changes in global environments during ancient and recent eras and to participate in the fixation of 200 GT of CO2 annually. In this review, I focus on several points that have not been discussed at length in the literature thus far.