A paper published in the recent issue of PNAS “Insights into the oxidative degradation of cellulose by a copper metalloenzyme that exploits biomass components” by Quinlan et al. succeeds in characterizing an important aspect of the breakdown of cellulose by enzymes. I’m interested in the use of cellulose in bioenergy purposes, but one of the major problems in its use is extreme recalcitrance of the polysaccaride. By fully understanding the enzymatic mechanisms of the breakdown of cellulose we can surpass a major scientific and economic challenge for the effective release of bioenergy from biomass.
Cellulose is typically broken down by fungi employing a suite of different enzymes. These enzymes are traditionally placed into two classes: endoglucanases and cellobiohydrolases. In this paper, the authors identify the enzymatic abilities of a newly recognized enzyme class, called the GH61 glycoside hydrolases (see Harris et al. for more information on GH61 glycoside hydrolases). The GH61 glycoside hydrolases greatly increase the efficiency of the endoglucanases and cellobiohydrolases and recent genome sequencing of brown rot fungi, such as Postia placenta, show numerous GH61 glycoside hydrolases.
The authors describe the 3D structure of a GH61 glycoside hydrolase from Thermoascus aurantiacus identifying the active site details and catalytic activity of the enzyme. It was identified that the GH61 glycoside hydrolase enzymes are oxidizing agents and the authors show the direct degradation of cellulose. Furthermore, the authors identify copper as the metal cofactor of the enzyme and show a unique methyl modification of a metal-coordinating histidine residue.
See here for commentary on the paper.
I’m just returning from the New Phytologist “Bioenergy Trees” symposium, which just took place from May 17th to 19th at INRA in Nancy, Lorraine, France, and I am pleased to say was a very productive meeting. Due to technical difficulties, I was not able to contribute to the online updates via Twitter, but if you’d like to follow the meeting developments you can read the Twitter feeds using the hashtag #26NPS or following @NewPhyt.
Fuels derived from cellulosic biomass are increasingly becoming a priority as we focus both on reducing the large amount of greenhouse gases we introduce into the atmosphere and our dependence on unsustainably sourced fossil reserves. Liquid or solid biofuels derived from cellulosic materials, such as trees, will address these criteria while also assisting agricultural development in rural areas by promoting sustainable coppice harvesting on marginal lands not suitable for consumption crop production. The use of next-generation genomics technologies, as well as more traditional biological research methods, will help develop and enhance tree growth in no- to low-input environments. Additionally, genomic resources will contribute to understanding the process of cell wall formation in woody plants and allow researchers to optimize the composition of plant cell walls for bioenergy concerns.
In the upcoming meeting “Bioenergy Trees” – sponsored by the journal The New Phytologist in their ongoing series of symposia – will address the development of trees and other woody biomass for bioenergy purposes. This meeting will be held at INRA-Nancy, in Nancy/Champenoux, France, from May 17th to 19th, 2011. Registration is now open. In addition to this very pertinent research topic, Nancy is truly a magical place, so it’s with great excitement that I tell you about this meeting.
In addition, The New Phytologist has announced the next round of symposia for 2012 here.