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- Title
The role of Rubisco kinetics and pyrenoid morphology in shaping the CCM of haptophyte microalgae.
- Authors
Heureux, Ana M. C.; Young, Jodi N.; Whitney, Spencer M.; Eason-Hubbard, Maeve R.; Lee, Renee B. Y.; Sharwood, Robert E.; Rickaby, Rosalind E. M.
- Abstract
The haptophyte algae are a cosmopolitan group of primary producers that contribute significantly to the marine carbon cycle and play a major role in paleo-climate studies. Despite their global importance, little is known about carbon assimilation in haptophytes, in particular the kinetics of their Form 1D CO2-fixing enzyme, Rubisco. Here we examine Rubisco properties of three haptophytes with a range of pyrenoid morphologies (Pleurochrysis carterae, Tisochrysis lutea, and Pavlova lutheri) and the diatom Phaeodactylum tricornutum that exhibit contrasting sensitivities to the trade-offs between substrate affinity (Km) and turnover rate (kcat) for both CO2 and O2. The pyrenoid-containing T. lutea and P. carterae showed lower Rubisco content and carboxylation properties (KC and kCcat) comparable with those of Form 1D-containing non-green algae. In contrast, the pyrenoid-lacking P. lutheri produced Rubisco in 3-fold higher amounts, and displayed a Form 1B Rubisco kCcat-KC relationship and increased CO2/O2 specificity that, when modeled in the context of a C3 leaf, supported equivalent rates of photosynthesis to higher plant Rubisco. Correlation between the differing Rubisco properties and the occurrence and localization of pyrenoids with differing intracellular CO2:O2 microenvironments has probably influenced the divergent evolution of Form 1B and 1D Rubisco kinetics.
- Subjects
MICROALGAE; CARBON dioxide fixation; PHAEODACTYLUM tricornutum; PRYMNESIOPHYCEAE; CARBOXYLATION; GREEN algae; PHYSIOLOGY
- Publication
Journal of Experimental Botany, 2017, Vol 68, Issue 14, p3959
- ISSN
0022-0957
- Publication type
Article
- DOI
10.1093/jxb/erx179