Isoleucine 309 acts as a C4 catalytic switch that increases ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) carboxylation rate in flaveria

Whitney, Spencer M. and Sharwood, Robert E. and Orr, Douglas and White, Sarah J. and Alonso, Hernan and Galmés, Jeroni (2011) Isoleucine 309 acts as a C4 catalytic switch that increases ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) carboxylation rate in flaveria. Proceedings of the National Academy of Sciences of the United States of America, 108 (35). pp. 14688-14693. ISSN 0027-8424

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Abstract

Improving global yields of important agricultural crops is a complex challenge. Enhancing yield and resource use by engineering improvements to photosynthetic carbon assimilation is one potential solution. During the last 40 million years C 4 photosynthesis has evolved multiple times, enabling plants to evade the catalytic inadequacies of the CO 2-fixing enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). Compared with their C 3 ancestors, C 4 plants combine a faster rubisco with a biochemical CO 2- concentrating mechanism, enabling more efficient use of water and nitrogen and enhanced yield. Here we show the versatility of plastome manipulation in tobacco for identifying sequences in C 4-rubisco that can be transplanted into C 3-rubisco to improve carboxylation rate (V C). Using transplastomic tobacco lines expressing native and mutated rubisco large subunits (L-subunits) from Flaveria pringlei (C 3), Flaveria floridana (C 3-C 4), and Flaveria bidentis (C 4), we reveal that Met-309-Ile substitutions in the L-subunit act as a catalytic switch between C 4 ( 309Ile; faster V C, lower CO 2 affinity) and C 3 ( 309Met; slower VC, higher CO 2 affinity) catalysis. Application of this transplastomic system permits further identification of other structural solutions selected by nature that can increase rubisco V C in C 3 crops. Coengineering a catalytically faster C 3 rubisco and a CO 2-concentrating mechanism within C 3 crop species could enhance their efficiency in resource use and yield.

Item Type:
Journal Article
Journal or Publication Title:
Proceedings of the National Academy of Sciences of the United States of America
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1000
Subjects:
ID Code:
80179
Deposited By:
Deposited On:
24 Jun 2016 10:20
Refereed?:
Yes
Published?:
Published
Last Modified:
11 Mar 2020 05:07