Discovery of a readily heterologously expressed Rubisco from the deep sea with potential for CO2 capture

Junli Zhang,Zhen Cai,Robert H Wilson,Guoxia Liu,Yin Li,Alonso I Carvajal

doi:10.1186/s40643-021-00439-6

Abstract

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), the key CO2-fixing enzyme in photosynthesis, is notorious for its low carboxylation. We report a highly active and assembly-competent Form II Rubisco from the endosymbiont of a deep-sea tubeworm Riftia pachyptila (RPE Rubisco), which shows a 50.5% higher carboxylation efficiency than that of a high functioning Rubisco from Synechococcus sp. PCC7002 (7002 Rubisco). It is a simpler hexamer with three pairs of large subunit homodimers around a central threefold symmetry axis. Compared with 7002 Rubisco, it showed a 3.6-fold higher carbon capture efficiency in vivo using a designed CO2 capture model. The simple structure, high carboxylation efficiency, easy heterologous soluble expression/assembly make RPE Rubisco a ready-to-deploy enzyme for CO2 capture that does not require complex co-expression of chaperones. The chemosynthetic CO2 fixation machinery of chemolithoautotrophs, CO2-fixing endosymbionts, may be more efficient than previously realized with great potential for next-generation microbial CO2 sequestration platforms.

Highlights

Photosynthesis uses light energy to convert inorganic CO2 into organic carbohydrates and forms the basis of most life on earth
Discovery of a highly active Form II RPE Rubisco Seven Form II Rubiscos from different microbes were selected for characterization (Additional file 2: Table S1)
The Rubisco from endosymbiotic bacteria which lived in the trophosome of the Riftia pachyptila (RPE Rubisco) showed the highest carboxylation activity in cellular solution protein (Additional file 2: Figure S2c)

Summary

Introduction

Photosynthesis uses light energy to convert inorganic CO2 into organic carbohydrates and forms the basis of most life on earth. Extensive structural and biochemical studies have been performed on the Form I Rubisco enzymes from plants, algae and cyanobacteria. They share a similar hexadecameric structure composed of eight large subunits and eight small subunits, and are notorious for their low carboxylation activities, with turnover numbers toward. Cyanobacterial Rubisco exhibit the highest activity among the Form I Rubiscos, the difficulty to achieve efficient heterologous soluble expression in E. coli, and other hosts, hampers the carbon fixation efficiency (Orr et al 2020; Wilson et al 2018; Zhou and Whitney 2019)

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