Mitochondrial phosphoenolpyruvate carboxylase contributes to carbon fixation in the diatom Phaeodactylum tricornutum at low inorganic carbon concentrations

0559180 - BC 2023 RIV GB eng J - Článek v odborném periodiku
Yu, G. - Nakajima, K. - Gruber, Ansgar - Bártulos, C.R. - Schober, A.F. - Lepetit, B. - Yohannes, E. - Matsuda, Y. - Kroth, P.G.
Mitochondrial phosphoenolpyruvate carboxylase contributes to carbon fixation in the diatom Phaeodactylum tricornutum at low inorganic carbon concentrations.
New Phytologist. Roč. 235, č. 4 (2022), s. 1379-1393. ISSN 0028-646X. E-ISSN 1469-8137
Institucionální podpora: RVO:60077344
Klíčová slova: C-4 photosynthesis * carbon concentrating mechanism (CCM) * diatoms * Phaeodactylum tricornutum * phosphoenolpyruvate carboxylases (PEPC) * reverse genetics * talen
Obor OECD: Cell biology
Impakt faktor: 9.4, rok: 2022
Způsob publikování: Open access
https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.18268

Photosynthetic carbon fixation is often limited by CO2 availability, which led to the evolution of CO2 concentrating mechanisms (CCMs). Some diatoms possess CCMs that employ biochemical fixation of bicarbonate, similar to C-4 plants, but whether biochemical CCMs are commonly found in diatoms is a subject of debate. In the diatom Phaeodactylum tricornutum, phosphoenolpyruvate carboxylase (PEPC) is present in two isoforms, PEPC1 in the plastids and PEPC2 in the mitochondria. We used real-time quantitative polymerase chain reaction, Western blots, and enzymatic assays to examine PEPC expression and PEPC activity, under low and high concentrations of dissolved inorganic carbon (DIC). We generated and analyzed individual knockout cell lines of PEPC1 and PEPC2, as well as a PEPC1/2 double-knockout strain. While we could not detect an altered phenotype in the PEPC1 knockout strains at ambient, low or high DIC concentrations, PEPC2 and the double-knockout strains grown under ambient air or lower DIC availability conditions showed reduced growth and photosynthetic affinity for DIC while behaving similarly to wild-type (WT) cells at high DIC concentrations. These mutants furthermore exhibited significantly lower C-13/C-12 ratios compared to the WT. Our data imply that in P. tricornutum at least parts of the CCM rely on biochemical bicarbonate fixation catalyzed by the mitochondrial PEPC2.
Trvalý link: https://hdl.handle.net/11104/0340548