Characterisation of carbon fixation proteins in the macroalgal biomass feedstock, Ulva spp.

Abstract

Ulva spp. is a macroalgae widely distributed and abundant in nature, however, its exploitation as a biofuel feedstock has been scarce due the lack of information about its metabolic functioning. On the other hand, microalgae have been extensively studied allowing understanding of the complexity of these organisms and, at the same time, providing a guide which could be extrapolated to macroalgal metabolic systems.
As an essential metabolic process, the study of carbon dioxide fixation and associated intracellular structures is fundamental in order to improve and engineer changes in algal biomass yield. As part of these intracellular components, the pyrenoid is a microcompartment where carbon dioxide is fixed by maintaining a CO2 rich environment around Rubisco. Although Rubisco is the main constituent of the pyrenoid matrix, it is not the only one and it is not efficient enough to carry out CO2 fixation by itself. Previous work in the model microalga Chlamydomonas reinhardtii has revealed the existence of a linker protein called EPYC1, whose main role is to bind Rubisco together to form a complex avoiding CO2 leakage.
To study pyrenoid in Ulva, a chloroplast isolation method was developed. Bioinformatics searches were performed in order to find a putative protein in the Ulva proteome with similar physicochemical properties to EPYC1. A single target candidate which fulfilled all physicochemical properties was identified. Finding of a putative of Ulva EPYC1-like protein allows for further studies.