Functional and Structural Characterization of a Novel Isoamylase from Ostreococcus tauri and Role of the N-Terminal Domain

HEDIN, N.; BARCHIESI, J.; GOMEZ CASATI, D.F.; BUSI, M.V.

THE OPEN BIOTECHNOLOGY JOURNAL

BENTHAM OPEN

Año: 2020 p. 1 - 11

1874-0707

Background: The debranching starch enzymes, isoamylase 1 and 2 are well-conserved enzymes present in almost all the photosynthetic organisms. These enzymes are involved in the crystallization process of starch and are key components which remove misplaced α-1,6 ramifications on the final molecule.Aim: In this work, we performed a functional and structural study of a novel isoamylase from Ostreococcus tauri.Methods: We identified conserved amino acid residues possibly involved in catalysis. We also identified a region at the N-terminal end that resembles a Carbohydrate Binding Domain (CBM), which is more related to the family CBM48, but has no spatial conservation of the residues involved in carbohydrate binding.Results: The cloning, expression and biochemical characterization of this N-terminal region confirmed that it binds to polysaccharides, showing greater capacity for binding to amylopectin rather than total starch or amylose. Conclusion:This module could be a variant of the CBM48 family or it could be classified within a new CBM family.