Sebastià Capó-Bauçà is a biologist who graduated from the University of Balearic Islands. He also completed a master’s degree in applied biotechnology and started his scientific career in the plant physiology group at the same university.
He obtained a pre-doctoral FPU Grant from the Spanish Ministry of Education to develop a pH thesis about Rubisco evolution in marine macrophytes. His PhD thesis was directed by Drs Jeroni Galmés and Concepción Iñiguez . His research aims to explore the potential kinetic malleability of Rubisco in nature, especially to provide clues for designing improved Rubiscos in the laboratory or to reveal Rubisco profiles with desired kinetic properties that could be successfully transplanted into crops.
Title: Rubisco kinetic in Posidonia seagrass species. A different evolutionary pathway from angiosperms Rubisco.
Webinar date: Tuesday 7th February 14.00 CET
Abstract: The enzyme Ribulose bisphosphate carboxylase-oxygenase (Rubisco) catalyses the unique quantitatively significant carbon fixation pathway worldwide. Due to this pivotal role, there is significant interest in understanding how the CO2-fixing properties of Rubisco have evolved in response to the different environmental conditions. Marine environments are particularly useful to see the adaptative evolution of Rubisco, due to the low CO2 availability and slow gas diffusion found in this environment. Nevertheless, Rubisco kinetic properties have been barely analyzed in marine organisms, being completely unknown in the species of the genus Posidonia, one of the most relevant genera among seagrasses. The genus Posidonia possesses a particularly asymmetric distribution, with most of the species being localized in Australian coastlines, and only one endemic species from the Mediterranean Sea. Our study reveals how this disjunctive geographical distribution and diverged phylogeny of Posidonia species, along with their CO2 concentrating mechanisms (CCMs), have impacted their Rubisco kinetic properties.
The Rubisco from Posidonia species showed lower carboxylation efficiencies and lower sensitivity to O2 inhibition than those measured for terrestrial C3 and C4-plant Rubiscos. Compared to the Australian Posidonia species, Rubisco from the Mediterranean P. oceanica had 1.5-2–fold lower carboxylation and oxygenation efficiencies, coinciding with effective CCMs and five Rubisco large subunit (RbcL) amino acid substitutions. Among the Australian Posidonia species, CCM effectiveness was higher in P. sinuosa and lower in the deep-living P. angustifolia, likely related to the 20–35% lower Rubisco carboxylation efficiency in P. sinuosa and the 2–fold higher Rubisco content in P. angustifolia. Our results suggest that the catalytic evolution of Posidonia Rubisco has been impacted by the low CO2 availability and gas exchange properties of marine environments, but with contrasting Rubisco kinetics according to the time of diversification among the species. As a result, the relationships between maximum carboxylation rate and CO2– and O2-affinities of Posidonia Rubiscos follow an alternative path to that characteristic of terrestrial angiosperm Rubiscos.