New breakthrough for VISTA scholar Zarah Forsberg

Abstract of the article published in Protein Science:

Bacterial proteins categorized as family 33 carbohydrate-binding modules (CBM33) were recently shown to cleave crystalline chitin, using a mechanism that involves hydrolysis and oxidation. We show here that some members of the CBM33 family cleave crystalline cellulose as demonstrated by chromatographic and mass spectrometry analysis of soluble products released from Avicel or filter paper upon incubation with CelS2, a CBM33-containing protein from Streptomyces coelicolor A3(2). These enzymes act synergistically with cellulases and may thus become important tools for efficient conversion of lignocellulosic biomass. Fungal proteins classified as GH61 that are known to act synergistically with cellulases, are likely to use a similar mechanism.

Read more: http://www.proteinscience.org/view/0/index.html 

Article in Science

This article is a follow-up to the article published in Science by the same research group at the Norwegian University of Life Sciences, Vincent Eijsink explains.

- In October 2010, Science published our manuscript "An oxidative enzyme boosting the enzymatic conversion of recalcitrant polysaccharides", by Vaaje-Kolstad G, Westereng B, Horn SJ, Liu Z, Zhai H, Sørlie M, Eijsink VGH (Science, 2010, Oct 8;330(6001):219-222).

In this paper we described a completely novel type of enzyme which may revolutionize the enzymatic conversion of plant biomass. This, of course, is of great importance considering the current interest in second generation biofuels and lignocellulose-based biorefineries. Although our data were from work on chitin, which is not even a plant polysaccharide, the impact of our findings for the enzymatic conversion of cellulose was immediately clear to the lignocellulose field. We are currently experiencing large interest in our findings (and our patent application), including from leading bioenergy-oriented enzyme companies.

The work published in Science was done on proteins classified as belonging to a protein family called "CBM33". These CBM33 proteins have so far been thought to only work on chitin. There is another class of proteins, classified as belonging to protein family GH61 and occurring in fungi only.

These proteins are structurally similar to CBM33 and are known to act synergistically with cellulases in cellulose degradation (PV Harris et al., Biochemistry. 2010, 49(15):3305-16). As we claimed in our Science paper, the mechanism of GH61 proteins is likely to be similar to the mechanism of CBM33 proteins, which was revealed in that paper. However, a mechanism for GH61 proteins has not yet been published.

Now, most importantly, in the meantime, we have found members of the CBM33 family that act on cellulose. We have been able to document large enhancing effects on cellulase efficiency and we show that the mechanism involves the oxidohydrolytic steps described in our original Science publication.

These results strengthen our previous findings and significantly broaden their implications. Furthermore, these findings show that these completely novel cellulose-converting enzymes occur in the bacterial world, and open up a novel avenue towards much more efficient enzymatic processing of cellulose. This is the very first time that this activity of a CBM33/GH61 protein is demonstrated. We know that similar data on a GH61 protein, the details of which we do not know, are on their way to the scientific literature, so we would like to publish our novel findings as fast as possible.