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Discovery of a RuBisCO-like Protein that Functions as an Oxygenase in the Novel D-Hamamelose Pathway

Kim, Suk Min, Lim, Hyun Seung, Lee, Sun Bok
Biotechnology and bioprocess engineering 2018 v.23 no.5 pp. 490-499
Ochrobactrum anthropi, carbon dioxide fixation, catalysts, chemical bonding, cleavage (chemistry), enzyme activity, metabolism, ribulose-bisphosphate carboxylase
Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the key catalyst of CO₂ fixation in nature. RuBisCO forms I, II, and III catalyze CO₂ fixation reactions, whereas form IV, also called the RuBisCO-like protein (RLP), is known to have no carboxylase or oxygenase activities. Here, we describe an RLP in Ochrobactrum anthropi ATCC 49188 (Oant_3067; HamA) that functions as an oxygenase in the metabolism of D-hamamelose, a branched-chain hexose found in most higher plants. The D-hamamelose pathway is comprised of five previously unknown enzymes: D-hamamelose dehydrogenase, D-hamamelono-lactonase, D-hamamelonate kinase, D-hamamelonate-2′,5-bisphosphate dehydrogenase (decarboxylating), and the RLP 3-keto-D-ribitol-1,5-bisphosphate (KRBP) oxygenase, which converts KRBP to 3-D-phosphoglycerate and phosphoglycolate. HamA represents the first RLP catalyzing the O₂-dependent oxidative C–C bond cleavage reaction, and our findings may provide insights into its applications in oxidative cleavage of organic molecules.