Cellulosomes: bacterial nanomachines for dismantling plant polysaccharides

• Published in: Nature reviews. Microbiology Vol. 15; no. 2; pp. 83 - 95
• Main Authors: Artzi, Lior, Bayer, Edward A., Moraïs, Sarah
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2017; Nature Publishing Group
• Subjects: 631/326/252/318; 631/326/2522; 631/326/41/1969; 631/326/41/2173; 631/326/41/2536; 631/326/41/2537; Bacteria; Biofuels; Botanical research; Cell Cycle Proteins - metabolism; Cell Wall - metabolism; Cellulose; Cellulosomes - enzymology; Cellulosomes - metabolism; Cellulosomes - ultrastructure; Chromosomal Proteins, Non-Histone - metabolism; Clostridium thermocellum - metabolism; Cohesins; Enzymes; Gene expression; Genetic research; Heterogeneity; Infectious Diseases; Life Sciences; Lignin; Lignin - metabolism; Medical Microbiology; Microbiology; Microorganisms; Observations; Parasitology; Plant Cells - metabolism; Plant genetics; Plant proteins; Plants - metabolism; Plants - microbiology; Properties; review-article; Saccharides; Sludge; Virology
• ISSN: 1740-1526; 1740-1534
• DOI: 10.1038/nrmicro.2016.164

Key Points Cellulosomes are self-assembled multienzyme complexes that are highly efficient at degrading lignocellulose, mainly owing to common substrate targeting and consequent enzyme proximity that, together, generate substrate channelling and synergistic action. Cellulosomes have been identified in several anaerobic bacteria, with each species presenting its own molecular arrangement with varying degrees of complexity. The prevalence of cellulosomes as rare but central components in various ecosystems reflects the benefits of this enzymatic strategy. The cohesin–dockerin interaction has been studied extensively and is one of the strongest non-covalent interactions known in nature. The composition of cellulosomes is regulated and varied by the nature of the growth substrate (carbon source) of the parent bacterium. The cellulosome, as one of the most efficient machineries for the degradation of plant cell walls, can potentially be used for the large-scale conversion of biomass. Owing to the modular nature of cellulosomes, cellulosomal components have been proposed for use in additional biotechnological applications, notably, together with other affinity systems. Cellulosomes are sophisticated multicomponent complexes that are used by bacteria to degrade cellulose from plant cell walls. In this review, Artzi, Bayer and Moraïs explore the structural and functional diversity of cellulosomes and their applications; for example, in microbial biofuel production. Cellulosomes are multienzyme complexes that are produced by anaerobic cellulolytic bacteria for the degradation of lignocellulosic biomass. They comprise a complex of scaffoldin, which is the structural subunit, and various enzymatic subunits. The intersubunit interactions in these multienzyme complexes are mediated by cohesin and dockerin modules. Cellulosome-producing bacteria have been isolated from a large variety of environments, which reflects their prevalence and the importance of this microbial enzymatic strategy. In a given species, cellulosomes exhibit intrinsic heterogeneity, and between species there is a broad diversity in the composition and configuration of cellulosomes. With the development of modern technologies, such as genomics and proteomics, the full protein content of cellulosomes and their expression levels can now be assessed and the regulatory mechanisms identified. Owing to their highly efficient organization and hydrolytic activity, cellulosomes hold immense potential for application in the degradation of biomass and are the focus of much effort to engineer an ideal microorganism for the conversion of lignocellulose to valuable products, such as biofuels.