Gonzalez-Esquer C Raul, Shubitowski Tyler B, Kerfeld Cheryl A
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 Department of Plant and Microbial Biology, UC Berkeley, Berkeley, California 94720 Berkeley Synthetic Biology Institute, UC Berkeley, Berkeley, California 94720
Plant Cell. 2015 Sep;27(9):2637-44. doi: 10.1105/tpc.15.00329. Epub 2015 Aug 28.
Bacterial microcompartments (BMCs) are self-assembling organelles that sequester segments of biochemical pathways within a protein shell. Given their functional diversity, BMCs constitute a rich source of metabolic modules for applications in synthetic biology. The carboxysome, the cyanobacterial BMC for CO(2) fixation, has attracted significant attention as a target for installation into chloroplasts and serves as the foundation for introducing other types of BMCs into plants. Carboxysome assembly involves a series of protein-protein interactions among at least six gene products to form a metabolic core, around which the shell assembles. This complexity creates significant challenges for the transfer, regulation, and assembly of carboxysomes, or any of the myriad of functionally distinct BMCs, into heterologous systems. To overcome this bottleneck, we constructed a chimeric protein in the cyanobacterium Synechococcus elongatus that structurally and functionally replaces four gene products required for carboxysome formation. The protein was designed based on protein domain interactions in the carboxysome core. The resulting streamlined carboxysomes support photosynthesis. This strategy obviates the need to regulate multiple genes and decreases the genetic load required for carboxysome assembly in heterologous systems. More broadly, the reengineered carboxysomes represent a proof of concept for a domain fusion approach to building multifunctional enzymatic cores that should be generally applicable to the engineering of BMCs for new functions and cellular contexts.
细菌微区室（BMCs）是一种自组装细胞器，它能将生化途径的各个部分隔离在蛋白质外壳内。鉴于其功能的多样性，BMCs构成了合成生物学应用中丰富的代谢模块来源。羧酶体是蓝细菌中用于固定CO₂的BMC，作为安装到叶绿体中的靶点已引起了极大关注，并为将其他类型的BMCs引入植物奠定了基础。羧酶体的组装涉及至少六种基因产物之间的一系列蛋白质-蛋白质相互作用，以形成一个代谢核心，外壳围绕该核心组装。这种复杂性给羧酶体或任何功能各异的BMCs转移到异源系统、进行调控和组装带来了重大挑战。为了克服这一瓶颈，我们在聚球藻中构建了一种嵌合蛋白，该蛋白在结构和功能上替代了羧酶体形成所需的四种基因产物。该蛋白是基于羧酶体核心中的蛋白质结构域相互作用设计的。由此产生的简化羧酶体支持光合作用。这一策略无需调控多个基因，并降低了异源系统中羧酶体组装所需的遗传负荷。更广泛地说，经过重新设计的羧酶体代表了一种结构域融合方法构建多功能酶核心的概念验证，这种方法应该普遍适用于为新功能和细胞环境对BMCs进行工程改造。
