Carbon isotope fractionation by an ancestral rubisco suggests that biological proxies for CO₂ through geologic time should be reevaluated.

ABSTRACT: The history of Earth's carbon cycle reflects trends in atmospheric composition convolved with the evolution of photosynthesis. Fortunately, key parts of the carbon cycle have been recorded in the carbon isotope ratios of sedimentary rocks. The dominant model used to interpret this record as a proxy for ancient atmospheric CO₂ is based on carbon isotope fractionations of modern photoautotrophs, and longstanding questions remain about how their evolution might have impacted the record. Therefore, we measured both biomass (ε_p) and enzymatic (ε_Rubisco) carbon isotope fractionations of a cyanobacterial strain (Synechococcus elongatus PCC 7942) solely expressing a putative ancestral Form 1B rubisco dating to ≫1 Ga. This strain, nicknamed ANC, grows in ambi

SUBMITTER: Wang RZ 

PROVIDER: S-EPMC10193938 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature