Enhanced cellulose degradation by nano-complexed enzymes: Synergism between a scaffold-linked exoglucanase and a free endoglucanase

Sarah Moraïs, Arnon Heyman, Yoav Barak, Jonathan Caspi, David B. Wilson, Raphael Lamed, Oded Shoseyov, Edward A. Bayer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

Protein molecular scaffolds are attracting interest as natural candidates for the presentation of enzymes and acceleration of catalytic reactions. We have previously reported evidence that the stable protein 1 (SP1) from Populus tremula can be employed as a molecular scaffold for the presentation of either catalytic or structural binding (cellulosomal cohesin) modules. In the present work, we have displayed a potent exoglucanase (Cel6B) from the aerobic cellulolytic bacterium, Thermobifida fusca, on a cohesin-bearing SP1 scaffold. For this purpose, a chimaeric form of the enzyme, fused to a cellulosomal dockerin module, was prepared. Full incorporation of 12 dockerin-bearing exoglucanase molecules onto the cohesin-bearing scaffold was achieved. Cellulase activity was tested on two cellulosic substrates with different levels of crystallinity, and the activity of the scaffold-linked exoglucanase was significantly reduced, compared to the free dockerin-containing enzyme. However, addition of relatively low concentrations of a free wild-type endoglucanase (T. fusca Cel5A) that bears a cellulose-binding module, in combination with the complexed exoglucanase resulted in a marked rise in activity on both cellulosic substrates. The endoglucanase cleaves internal sites of the cellulose chains, and the new chain ends of the substrate were now readily accessible to the scaffold-borne exoglucanase, thereby resulting in highly effective, synergistic degradation of cellulosic substrates.

Original languageAmerican English
Pages (from-to)205-211
Number of pages7
JournalJournal of Biotechnology
Volume147
Issue number3-4
DOIs
StatePublished - Jun 2010

Bibliographical note

Funding Information:
The authors are grateful for the contributions of Prof. Yitzhak Hadar (Faculty of Agriculture, Hebrew University of Jerusalem) to this work. This research was supported by a grant from the United States-Israel Binational Science Foundation (BSF), Jerusalem, Israel , the Brazilian friends of the Weizmann Institute of Science Alternative Energy Research Initiative (AERI) and by the Israel Science Foundation (grant nos. 966/09 and 159/07 ). EAB is the incumbent of The Maynard I. and Elaine Wishner Chair of Bio-organic Chemistry at the Weizmann Institute of Science.

Keywords

  • Biofuels
  • Cellulases
  • Cohesin-dockerin recognition
  • Molecular scaffold
  • Nanofabrication
  • SP1
  • Self-assembly

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