Structural determinants invertigation of endo and exo arabinanases mode of action from bovine rumen metagenomic

Abstract

Arabinanases are glycoside hydrolases which belong to the GH43 family, possessing a key role on pectin-hemicellulose material degradation. These enzymes participate of diverse catabolic pathways in fungus and bacteria when these microorganisms are exposed to low glucose environment, using the arabinose as carbon source. For plant seeds, these enzymes have an important role on energetic metabolism after germination, besides their contribution on cellular vegetal wall dynamics. Recently, these enzymes have attracted attention due to their applications in diverse areas, such as food industry, organic synthesis and lignocellulose material to biofuels production. Despite of arabinanases great physiologic importance, they are poorly studied compared to other glycoside hydrolases, like xylanases and celulases. In this scenario, a new enzyme prospection approach has been the metagenomic, revealing significant divergence among them and those which have already been functionally and structurally characterized. ARN2 and ARN3 are, respectively, endo-±-1,5-L-arabinanase and exo-±-1,5-L-arabinanase obtained from bovine rumen metagenomic library, beyond their peculiar characteristics, such as loops insertions into the catalytic interface. Therefore, this project´s aims are the crystalline structure determination of both of these enzymes, and the stability evaluation relative to temperature and chemical agents in order to correlate to biological functions and possible biotechnological applications. The generated knowledge will be instrumental to engineer these proteins, directing to potential industry use or as model to re-draw other enzymes involvolved on hemicelluloses modification.