Biophysical analysis of the structural evolution of substrate specificity in RuBisCO
Saroj Poudel, Douglas H. Pike, Hagai Raanan, Joshua A. Mancini, Vikas Nanda, Rosalind E. M. Rickaby, Paul G. Falkowski
Abstract
Significance RuBisCO, the most abundant enzyme on Earth, catalyzes the fixation of CO 2 to form an organic acid. It does not clearly discriminate between CO 2 and O 2 . Reaction with the former leads to the productive formation of organic carbon; reaction with the latter leads to a metabolically futile, but energetically costly pathway. To elucidate how the enzyme discriminates between CO 2 and O 2 , we used computational approaches to identify regions around the active site that play key roles in differentiating the substrates. Our research reveals that the specificity of the enzyme is strongly correlated with the structure of the binding channel in the active site. This work poses a potential pathway to genetically engineer more efficient RuBisCOs.