Journal
JOURNAL OF EXPERIMENTAL BOTANY
Volume 67, Issue 11, Pages 3445-3456Publisher
OXFORD UNIV PRESS
DOI: 10.1093/jxb/erw163
Keywords
Algae; carbon fixation; diatoms; kinetics; photosynthesis; Rubisco
Categories
Funding
- ANU [CE140100015]
- NSF [1040965, 104095]
- Clarendon Scholarship, Oxford
- ARC DECRA [DE13010760]
- ERC [SP2-GA-2008-200915]
- Australian Research Council [CE14010001]
- Emerging Frontiers
- Direct For Biological Sciences [1040965] Funding Source: National Science Foundation
Ask authors/readers for more resources
Broad variations in the CO2 fixation kinetics of diatom Rubisco indicate novel mechanistic diversity and large differences in their carbon-concentrating mechanism.While marine phytoplankton rival plants in their contribution to global primary productivity, our understanding of their photosynthesis remains rudimentary. In particular, the kinetic diversity of the CO2-fixing enzyme, Rubisco, in phytoplankton remains unknown. Here we quantify the maximum rates of carboxylation (k (cat) (c)), oxygenation (k (cat) (o)), Michaelis constants (K (m)) for CO2 (K (C)) and O-2 (K (O)), and specificity for CO2 over O-2 (S-C/O) for Form I Rubisco from 11 diatom species. Diatom Rubisco shows greater variation in K (C) (23-68 A mu M), S-C/O (57-116mol mol(-1)), and K (O) (413-2032 A mu M) relative to plant and algal Rubisco. The broad range of K (C) values mostly exceed those of C-4 plant Rubisco, suggesting that the strength of the carbon-concentrating mechanism (CCM) in diatoms is more diverse, and more effective than previously predicted. The measured k (cat) (c) for each diatom Rubisco showed less variation (2.1-3.7s(-1)), thus averting the canonical trade-off typically observed between K (C) and k (cat) (c) for plant Form I Rubisco. Uniquely, a negative relationship between K (C) and cellular Rubisco content was found, suggesting variation among diatom species in how they allocate their limited cellular resources between Rubisco synthesis and their CCM. The activation status of Rubisco in each diatom was low, indicating a requirement for Rubisco activase. This work highlights the need to better understand the correlative natural diversity between the Rubisco kinetics and CCM of diatoms and the underpinning mechanistic differences in catalytic chemistry among the Form I Rubisco superfamily.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available