14-03: Insights into the role of Swollenin in enzymatic biomass deconstruction

Currently, the biochemical conversion of biomass to fuels and chemicals requires a large enzyme/protein loading to carry out effective hydrolysis of the cellulose. One strategy for lowering the amount (and therefore cost) of the enzymes, is to exploit the “recently-discovered” non-hydrolytic proteins involved in biomass deconstruction. These proteins are thought to synergize with the hydrolytic biomass degrading enzymes in a manner which enables more efficient biomass conversion at lower enzyme loadings. The non-hydrolytic proteins can be grouped into two families: those with an oxidative catalytic mechanism, such as GH61, and those with no detectable hydrolytic or oxidative activity. In the work that will be described we have looked at a variety of “accessory proteins”. The presentation will focus on Swollenin, a non-hydrolytic, non-oxidative protein, which has been shown to disrupt the structure of several model cellulosic substrates, subsequently enhancing the accessibility of these substrates to enzymatic attack. The disruptive effects of Swollenin on a commercially relevant pretreated lignocellulosic substrate (steam pretreated corn stover) and its synergistic interactions with specific monocomponent hydrolytic enzymes will be described. The possible role of “accessory proteins” in the amorphogenesis step of enzymatic deconstruction of biomass will be discussed as will the broader role that non-hydrolytic, non-oxidative proteins might play in the overall biomass-to-sugars process.