Cellulosomes - promising supramolecular machines of anaerobic cellulolytic microorganisms.
Cellulosomes - promising supramolecular machines of anaerobic cellulolytic microorganisms.
复制标题
纤维素体 - 有前途的厌氧纤维素分解微生物的超分子机器。
作者：
M. Vodovnik;R. Marinšek
纤维素是植物细胞壁的主要结构成分，因此是自然界中含量最丰富的碳水化合物。然而，从这种丰富的能源中提取能量受到其顽固性的限制。植物细胞壁的降解需要多种酶的协同作用，包括多种纤维素酶、半纤维素酶、果胶酶等。同时，好氧纤维素分解微生物在其环境中释放大量协同作用的游离酶，大多数厌氧微生物进化出更有效的策略来优化植物细胞壁的降解过程，例如产生胞外多酶复合体(纤维素体)。纤维素体由至少一个被称为支架蛋白的核心结构蛋白组成，它牢固地结合许多酶亚基，通常也在底物结合中起主要作用。尽管细胞体的一般结构似乎是通用的，但不同微生物在复杂成分的数量和特性上确实存在差异。本文综述了有关纤维素体的研究现状，重点介绍了3种研究最深入的纤维素分解梭菌、一种具有代表性的瘤胃细菌以及有关厌氧真菌的新发现。还讨论了构建人工工程纤维素体系统(设计者纤维素体)的努力以及它们的生物技术潜力。
Cellulose is the main structural component of plant cell wall and thus the most abundant carbohydrate in nature. However, extracting the energy from this abundant source is limited by its recalcitrant nature. The hydrolysis of plant cell wall requires synergystic action of different enzymes, including multiple cellulases, hemicellulases, pectinases, etc. Meanwhile aerobic cellulolytic microorganisms release large quantities of synergistically acting free enzymes in their environment, most anaerobic microorganisms evolved more efficient strategies to optimize the process of plant cell wall degradation, for example production of extracellular multi-enzyme complexes (cellulosomes). Cellulosomes consist of at least one core structural protein, named scaffoldin, which firmly binds numerous enzymatic subunits, and usually also plays a major role in substrate binding. Although the general structure of cellulosomes seems universal, differences in number and identity of complex components do exist among microorganisms. The article surveys the current knowledge about cellulosomes, focusing on three best investigated cellulolytic clostridia, one representative of ruminal bacteria and novel findings concerning anaerobic fungi. Efforts in construction of artificially engineered cellulosomal systems (designer cellulosomes) as well as their biotechnological potential are also discussed.