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标题：Biophysical analysis of the structural evolution of substrate specificity in RuBisCO
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作者：Saroj Poudel ; Douglas H. Pike ; Hagai Raanan 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2020
卷号：117
期号：48
页码：30451-30457
DOI：10.1073/pnas.2018939117
出版社：The National Academy of Sciences of the United States of America
摘要：Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the most abundant enzyme on Earth. However, its catalytic rate per molecule of protein is extremely slow and the binding of the primary substrate, CO 2 , is competitively displaced by O 2. Hence, carbon fixation by RuBisCO is highly inefficient; indeed, in higher C3 plants, about 30% of the time the enzyme mistakes CO 2 for O 2 . Using genomic and structural analysis, we identify regions around the catalytic site that play key roles in discriminating between CO 2 and O 2 . Our analysis identified positively charged cavities directly around the active site, which are expanded as the enzyme evolved with higher substrate specificity. The residues that extend these cavities have recently been under selective pressure, indicating that larger charged pockets are a feature of modern RuBisCOs, enabling greater specificity for CO 2 . This paper identifies a key structural feature that enabled the enzyme to evolve improved CO 2 sequestration in an oxygen-rich atmosphere and may guide the engineering of more efficient RuBisCOs.
关键词：RuBisCO ; protein engineering ; binding selectivity ; protein structural evolution