Linkage between the distribution and biochemical properties of RuBisCO and CODH enzymes and abiotic properties in thermally and chemically distinct deep-sea hydrothermal vent systems

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The project aims at investigating the distribution and biochemical properties of key enzymes associated with autotrophic CO2 fixation pathways from thermally and chemically distinct hydrothermal deep-sea vent environments on the Mid-Atlantic Ridge. Within this scope we will focus on two key enzymes: the carbon monoxide dehydrogenase (CODH) of the reductive acetyl coenzyme A pathway and the ribulose-1,5-bisphosphate carboxylase (RuBisCOs) of the Calvin Benson Bassham cycle. These two pathways and respective key enzymes were chosen among the autotrophic CO2 fixation pathways because they are contrasting with respect to the energy (ATP) required for operating the autotrophic pathway, the temperature range of the organisms known to fix the CO2 autotrophically and the oxygen tolerance/sensitivity of the respective key enzymes. For the proposed study we have constructed five metagenomic fosmid libraries from abiotically distinct hydrothermal vents (energy-rich versus energy-poor, oxygen-rich versus oxygen-poor and high temperature versus low temperature) and have established function-based approaches to seek recombinant CODH and RuBisCOs from these metagenomic fosmid libraries. The successful search for recombinant CODHs and RuBisCOs in metagenomic libraries constructed from deep-sea hydrothermal vent samples will expand our knowledge of the interconnection between the distribution and biochemical properties of CODH and RuBisCOs and the abiotic parameters of the natural hydrothermal habitats.