Molecular insight into cellulose degradation by the phototrophic green alga Scenedesmus

VELAZQUEZ, M.B.; BUSI, M.V.; GOMEZ CASATI, D.F.; DASGUPTA, C.N.; BARCHIESI, J.

PROTEINS: STRUCTURE, FUNCTION AND GENETICS

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2023

0887-3585

Lignocellulose is the most abundant natural biopolymer on earth and a potential rawmaterial for the production of fuels and chemicals. However, only some organismssuch as bacteria and fungi produce enzymes that metabolize this polymer. In thiswork we have demonstrated the presence of cellulolytic activity in the supernatantof Scenedesmus quadricauda cultures and we identified the presence of extracellularcellulases in the genome of five Scenedesmus species. Scenedesmus is a green algawhich grows in both freshwater and saltwater regions as well as in soils, showinghighly flexible metabolic properties. Sequence comparison of the different identifiedcellulases with hydrolytic enzymes from other organisms using multisequence alignmentsand phylogenetic trees showed that these proteins belong to the families ofglycosyl hydrolases 1, 5, 9, and 10. In addition, most of the Scenedesmus cellulasesshowed greater sequence similarity with those from invertebrates, fungi, bacteria,and other microalgae than with the plant homologs. Furthermore, the data obtainedfrom the three dimensional structure showed that both, their global structure and themain amino acid residues involved in catalysis and substrate binding are well conserved.Based on our results, we propose that different species of Scenedesmus couldact as biocatalysts for the hydrolysis of cellulosic biomass produced from sunlight.