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Cell-surface attachment of bacterial cellulosomes

 In a long–lasting series of collaborations with national and international institutions including the Faculty of Sciences and Technology (Universidade Nova de Lisboa), The Weizmann Institute of Science (Israel), Newcastle University (UK) and Queen’s University (Canada), FMV-CIISA researchers are contributing to the elucidation of the unique molecular mechanisms used by anaerobic bacteria for cellular attachment of cellulosomes. Cellulosomes (Fig. 1) are one of Nature’s most intricate multi-enzyme complexes dedicated to degrade cellulosic biomass to simpler sugars. Knowledge about this very efficient nano-machine has enormous interest not only to produce bioethanol, but also for the construction of other dynamic protein assemblies. The research work that reveals how this assembly attaches to the bacterial cell walls from Clostridium thermocellum and Acetivibrio cellulolyticus was recently published in Scientific Reports: http://www.nature.com/articles/srep38292

Attachment is achieved through dynamic interaction of cohesin and dockerin modules, as schematized in Fig. 2. The structures of five different cohesin-dockerin complexes (Fig. 3), from the two bacteria, were solved by X-ray Crystallography to reveal the functional complexity of cellulosome recruitment to the cell envelope. In contrast to a previously suggested “static” model, the data support the hypothesis that binding of large cellulosomal complexes to the bacterial surface is mediated by a dual-binding mode that, nonetheless, assumes a diversity of mechanisms in different bacteria.