Cellulosomics of the cellulolytic thermophile Clostridium clariflavum

Lior Artzi, Bareket Dassa, Ilya Borovok, Melina Shamshoum, Raphael Lamed, Edward A. Bayer

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Clostridium clariflavum is an anaerobic, thermophilic, Gram-positive bacterium, capable of growth on crystalline cellulose as a single carbon source. The genome of C. clariflavum has been sequenced to completion, and numerous cellulosomal genes were identified, including putative scaffoldin and enzyme subunits.

Results: Bioinformatic analysis of the C. clariflavum genome revealed 49 cohesin modules distributed on 13 different scaffoldins and 79 dockerin-containing proteins, suggesting an abundance of putative cellulosome assemblies. The 13-scaffoldin system of C. clariflavum is highly reminiscent of the proposed cellulosome system of Acetivibrio cellulolyticus. Analysis of the C. clariflavum type I dockerin sequences indicated a very high level of conservation, wherein the putative recognition residues are remarkably similar to those of A. cellulolyticus. The numerous interactions among the cellulosomal components were elucidated using a standardized affinity ELISA-based fusion-protein system. The results revealed a rather simplistic recognition pattern of cohesin-dockerin interaction, whereby the type I and type II cohesins generally recognized the dockerins of the same type. The anticipated exception to this rule was the type I dockerin of the ScaB adaptor scaffoldin which bound selectively to the type I cohesins of ScaC and ScaJ.

Conclusions: The findings reveal an intricate picture of predicted cellulosome assemblies in C. clariflavum. The network of cohesin-dockerin pairs provides a thermophilic alternative to those of C. thermocellum and a basis for subsequent utilization of the C. clariflavum cellulosomal system for biotechnological application.

Original languageEnglish
Article number100
JournalBiotechnology for Biofuels
Volume7
Issue number1
DOIs
StatePublished - 1 Jul 2014

Keywords

  • Biofuels
  • Biomass degradation
  • CBM
  • Cellulases
  • Cellulosomes
  • Cohesin
  • Dockerin
  • Glycoside hydrolases
  • Scaffoldin

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