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

该项目的目的是调查与大西洋中脊热液和化学性质不同的深海喷口环境中的自养CO2固定途径有关的关键酶的分布和生物化学特性。在这个范围内，我们将集中在两个关键酶：一氧化碳脱氢酶（CODH）的还原乙酰辅酶A途径和核酮糖-1，5-二磷酸羧化酶（RuBisCOs）的卡尔文本森-巴斯舍姆循环。在自养CO2固定途径中选择这两种途径和各自的关键酶，因为它们在操作自养途径所需的能量（ATP）、已知以自养方式固定CO2的生物体的温度范围和各自关键酶的氧耐受性/敏感性方面形成对比。对于所提出的研究，我们已经构建了五个宏基因组fosmid库从非生物不同的热液喷口（能源丰富与能源贫乏，富氧与缺氧和高温与低温），并建立了基于功能的方法，以寻求重组CODH和RuBisCOs从这些宏基因组fosmid库。从深海热液喷口样品构建的宏基因组文库中成功寻找重组CODH和RuBisCOs，将扩大我们对CODH和RuBisCOs的分布和生物化学性质与天然热液生境的非生物参数之间相互关系的了解。

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.