Title :

Crystal Structure of the Chlamydomonas Starch Debranching Enzyme Isoamylase ISA1 Reveals Insights into the Mechanism of Branch Trimming and Complex Assembly

Author(s) :

Sim, Lyann [Auteur]
University of Copenhagen = Københavns Universitet [UCPH]
IT University of Copenhagen [ITU]
Beeren, Sophie R. [Auteur]
University of Copenhagen = Københavns Universitet [UCPH]
Findinier, Justin [Auteur]
Unité de Glycobiologie Structurale et Fonctionnelle - UMR 8576 [UGSF]
Dauvillee, David [Auteur]
Unité de Glycobiologie Structurale et Fonctionnelle UMR 8576 [UGSF]
Ball, Steven [Auteur]
Unité de Glycobiologie Structurale et Fonctionnelle UMR 8576 [UGSF]
Henriksen, Anette [Auteur]
University of Copenhagen = Københavns Universitet [UCPH]
Palcic, Monica M. [Auteur]
University of Copenhagen = Københavns Universitet [UCPH]

Journal title :

THE JOURNAL OF BIOLOGICAL CHEMISTRY

Volume number :

289

Pages :

22991-23003

Publication date :

2014-08-15

ISSN :

0021-9258, 1083-351X

English keyword(s) :

Protein Structure, Tertiary
Crystal Structure
X-ray Crystallography
Isoamylase
Carbohydrate Biosynthesis
Chlamydomonas
Debranching Enzyme
Chlamydomonas reinhardtii
Glucans
Starch Metabolism
Glycosidase
Plant Proteins
Polysaccharide

HAL domain(s) :

Chimie/Chimie théorique et/ou physique

English abstract : [en]

The starch debranching enzymes isoamylase 1 and 2 (ISA1 and ISA2) are known to exist in a large complex and are involved in the biosynthesis and crystallization of starch. It is suggested that the function of the complex ...
Show more >The starch debranching enzymes isoamylase 1 and 2 (ISA1 and ISA2) are known to exist in a large complex and are involved in the biosynthesis and crystallization of starch. It is suggested that the function of the complex is to remove misplaced branches of growing amylopectin molecules, which would otherwise prevent the association and crystallization of adjacent linear chains. Here, we investigate the function of ISA1 and ISA2 from starch producing alga Chlamydomonas. Through complementation studies, we confirm that the STA8 locus encodes for ISA2 and sta8 mutants lack the ISA1*ISA2 heteromeric complex. However, mutants retain a functional dimeric ISA1 that is able to partly sustain starch synthesis in vivo. To better characterize ISA1, we have overexpressed and purified ISA1 from Chlamydomonas reinhardtii (CrISA1) and solved the crystal structure to 2.3 Å and in complex with maltoheptaose to 2.4 Å. Analysis of the homodimeric CrISA1 structure reveals a unique elongated structure with monomers connected end-to-end. The crystal complex reveals details about the mechanism of branch binding that explains the low activity of CrISA1 toward tightly spaced branches and reveals the presence of additional secondary surface carbohydrate binding sites.Show less >

Language :

Anglais

Audience :

Non spécifiée

Administrative institution(s) :

CNRS
Université de Lille

Collections :

• Unité de Glycobiologie Structurale et Fonctionnelle (UGSF) - UMR 8576

Research team(s) :

Plant Storage Polysaccharides
Génétique microbienne

Submission date :

2020-02-12T15:45:09Z
2021-02-26T10:17:28Z