Bioinformatic Analysis of Glycoside Hydrolases in the Proteomes of Mesophilic and Thermophilic Actinobacteria

Abstract

Petroleum reserves are rapidly depleting and alternative renewable sources of energy need to be developed to meet the energy demands of the planet. Lignocellulose has been recognized as a highly promising and renewable resource for the development of clean energy. Thermophilic microbes and thermostable enzymes are being sought for biological conversion of lignocellulose into biofuels. The phylum Actinobacteria includes several efficient cellulose-degrading microorganisms. Genomes of several Actinobacteria have been completely sequenced and deposited in public databases, which are a great resource for uncovering new enzymes and targets for biotechnology. We searched the predicted proteomes of 69 Actinobacteria for the homologs of 20 glycoside hydrolase families relevant to lignocellulose degradation and identified 589 glycoside hydrolase homologs. We analyzed (1) the distribution of the glycoside hydrolase homologs across mesophilic and thermophilic Actinobacteria (2), the domain architecture of cellulases (from GH5 and GH6 families) and xylanases (from GH10 and GH11 families) from mesophilic and thermophilic Actinobacteria, and (3) asymmetric amino acid substitutions between mesophilic and thermophilic glycoside hydrolases. Overall, our data provide new insights into the distribution of different glycoside hydrolases in Actinobacteria as well as into the thermostability features of cellulases and xylanases from Actinobacteria. Our findings provide a basis for genetic engineering of glycoside hydrolases as well as new targets for biotechnology. Keywords