Structure, mechanism and function in the ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) superfamily

点击翻译按钮获取中文摘要

D-Ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) is one of the most abundant en-zymes in the biosphere and catalyzes the key reaction of the Calvin cycle, the major process of CO2-fixation on earth. The RubisCO superfamily includes four distinct types of proteins. TYPE I, II and III RubisCOs are true CO2-fixing enzymes that operate in plants (TYPE I), bacteria (TYPE I and II), and archaea (TYPE III), respectively. In contrast to that, TYPE IV proteins (bacterial) miss residues essen-tial for a carboxylation reaction and consequently lack the ability to fix CO2. These “RUBISCO-LIKE PROTEINS” (RLP) fall into six divergent clades that are expected to catalyze different reactions. This study aims at identifying the reactions catalyzed by RLPs of different clades and deciphering their biological function. A combined approach of structural and biochemical methods will be used to ex-plore the substrate and reaction specificity of individual RLPs. The physiological role of RLPs will be tested by cell extract experiments and mutagenic studies that may unravel novel metabolic pathways. The diversification of catalytical functions within the RubisCO superfamily will be investigated by structural studies and site directed mutagenesis to modify and to introduce “novel” functions into the enzyme scaffold. The results of this study may extend our knowledge on the biological significance of this important superfamily of enzymes, as well as on the evolution and diversification of the reactions catalyzed by its single members. This might also be of relevance for an (agriculturally important) engineering of RubisCO, or the development of biotechnologically applicable carboxylases.