期刊
JOURNAL OF EXPERIMENTAL BOTANY
卷 68, 期 14, 页码 3959-3969出版社
OXFORD UNIV PRESS
DOI: 10.1093/jxb/erx179
关键词
Algae; carbon-concentrating mechanisms; Haptophyta; pyrenoid; Rubisco
资金
- Clarendon Scholarship
- Oxford and ANU visiting scholar [CE140100015]
- Australian Research Council Grant [CE14010001]
- ARC DECRA scheme [DE13010760]
- ERC [SP2-GA-2008-200915]
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 (K-m) and turnover rate (k(cat)) for both CO2 and O-2. The pyrenoid-containing T. lutea and P. carterae showed lower Rubisco content and carboxylation properties (KC and k(cat)(C)) 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 k(cat)(C)-KC relationship and increased CO2/O-2 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:O-2 microenvironments has probably influenced the divergent evolution of Form 1B and 1D Rubisco kinetics.
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