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

HEDÍN, NICOLAS; BARCHIESI, JULIETA; GOMEZ-CASATI, DIEGO F.; BUSI, MARÍA V.

The Open Biotechnology Journal

Bentham Open

Año: 2020 vol. 14 p. 1 - 11

1874-0707

Abstract:Background:The debranching starch enzymes, isoamylase 1 and 2 are well-conserved enzymes present in almost all the photosynthetic organisms. Theseenzymes are involved in the crystallization process of starch and are key components which remove misplaced α-1,6 ramifications on the finalmolecule.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 aCarbohydrate Binding Domain (CBM), which is more related to the family CBM48, but has no spatial conservation of the residues involved incarbohydrate binding.Results:The cloning, expression and biochemical characterization of this N-terminal region confirmed that it binds to polysaccharides, showing greatercapacity 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.