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

该项目旨在研究大西洋中脊深海热液喷口环境中与自养二氧化碳固定途径相关的关键酶的分布和生化特性。在这个范围内，我们将重点关注两个关键酶：还原性乙酰辅酶A途径的一氧化碳脱氢酶（CODH）和卡尔文本森巴萨姆循环的核酮糖-1,5-二磷酸羧化酶（RuBisCOs）。这两种途径和各自的关键酶被选择在自养二氧化碳固定途径中，因为它们在运行自养途径所需的能量（ATP）、已知的生物自养固定二氧化碳的温度范围和各自关键酶的氧耐受性/敏感性方面形成了对比。在这项研究中，我们从非生物不同的热液喷口（富能与贫能、富氧与贫氧、高温与低温）构建了5个宏基因组化石文库，并建立了基于功能的方法从这些宏基因组化石文库中寻找重组CODH和RuBisCOs。在深海热液喷口样品构建的宏基因组文库中成功寻找到重组CODH和RuBisCOs，将扩大我们对CODH和RuBisCOs的分布和生化特性与天然热液栖息地非生物参数之间相互关系的认识。

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.