Towards a Structure Based Mechanism for the Function of the Carboxysome, the Prototype Bacterial Organelle

智力优势：羧体是在许多自养细菌中发现的多面体蛋白质微格。它们由一层薄的蛋白质壳组成，充满了1，5-二磷酸羧化酶/加氧酶(Rubisco)。这项研究寻求这些细菌通过将二氧化碳固定酶(Rubisco)包装成羧基体而获得优势的问题的答案。PI先前表明，一种与羧体外壳紧密相关的独特的碳水解酶(CA)通过介导丰富的细胞质碳酸氢盐以二氧化碳的形式定向转移到羧体内部，从而提高Rubisco的催化效率。外壳阻止重碳酸盐和二氧化碳扩散的能力将气体困在内部，在那里它被Rubisco固定。结构和分子生物学方法将与遗传和生化实验相结合，以进一步阐明微室的结构和功能特征，从而更深入地了解其在微生物碳代谢中的作用。广泛影响：鉴于含有羧基的生物体对二氧化碳固定的巨大贡献以及它们的新陈代谢对全球碳循环的影响，计划开展的工作的更广泛的影响将是阐明控制碳循环并影响天气和气候的最基本和核心的生化过程之一。参与该项目的研究生和本科生将获得生化和分子生物学研究方法的经验。通过与该机构和其他机构的科学家的持续合作，这些学生将获得对跨学科科学方法的欣赏。私人投资机构将继续积极招募代表不足的群体(如少数族裔和妇女)的成员，作为本科生和研究生研究人员参与该项目。

Intellectual Merit:Carboxysomes are polyhedral protein microcompartments found in many autotrophic bacteria. They are composed of a thin protein shell and are filled with 1,5-bisphosphate carboxylase/oxygenase (RubisCO). This research seeks answers to the question of the advantage these bacteria derive from packaging their carbon dioxide fixing enzyme (RubisCO) into carboxysomes. The PIs previously showed that a unique carbonic anhydrase (CA), which is tightly associated with the carboxysome shell, enhances RubisCO's catalytic efficiency by mediating what appears to be a directional transfer of abundant cytoplasmic bicarbonate to the carboxysome interior as carbon dioxide. The ability of the shell to impede diffusion of bicarbonate and carbon dioxide traps the gas in the interior, where it is fixed by RubisCO. Structural and molecular biological approaches will be combined with genetic and biochemical experiments to further elucidate structural and functional features of the microcompartment that will yield a deeper understanding of its role in microbial carbon metabolism.Broader Impacts: Given the large contribution of carboxysome-containing organisms towards carbon dioxide fixation and the impact of their metabolism on the global carbon cycle, broader implications of the work planned will be the elucidation of one of the most basic and central biochemical processes that controls the carbon cycle and influence weather and climate.Graduate and undergraduate students participating in the project will gain experience in biochemical and molecular biological research approaches. Through ongoing collaborations with scientists at this and other institutions, these students will gain an appreciation of interdisciplinary scientific approaches. The PIs will continue their practice of actively recruiting members of underrepresented groups (e.g. ethnic minorities and women) to participate in the project as undergraduate and graduate student researchers.