4HLN

Structure of barley starch synthase I in complex with maltooligosaccharide


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.174 

wwPDB Validation 3D Report Full Report



Literature

Structure of starch synthase I from barley: insight into regulatory mechanisms of starch synthase activity

Cuesta-Seijo, J.A.Nielsen, M.M.Marri, L.Tanaka, H.Beeren, S.R.Palcic, M.M.

(2013) Acta Crystallogr D Biol Crystallogr 69: 1013-1025

  • DOI: 10.1107/S090744491300440X
  • Primary Citation of Related Structures:  
    4HLN

  • PubMed Abstract: 
  • Starch, a polymer of glucose, is the major source of calories in the human diet. It has numerous industrial uses, including as a raw material for the production of first-generation bioethanol. Several classes of enzymes take part in starch biosynthes ...

    Starch, a polymer of glucose, is the major source of calories in the human diet. It has numerous industrial uses, including as a raw material for the production of first-generation bioethanol. Several classes of enzymes take part in starch biosynthesis, of which starch synthases (SSs) carry out chain elongation of both amylose and amylopectin. Plants have five classes of SS, each with different roles. The products of the reaction of SS are well known, but details of the reaction mechanism remain obscure and even less is known of how different SSs select different substrates for elongation, how they compete with each other and how their activities are regulated. Here, the first crystal structure of a soluble starch synthase is presented: that of starch synthase I (SSI) from barley refined to 2.7 Å resolution. The structure captures an open conformation of the enzyme with a surface-bound maltooligosaccharide and a disulfide bridge that precludes formation of the active site. The maltooligosaccharide-binding site is involved in substrate recognition, while the disulfide bridge is reflective of redox regulation of SSI. Activity measurements on several SSI mutants supporting these roles are also presented.


    Organizational Affiliation

    Carlsberg Laboratory, Gamle Carlsberg Vej 10, 1799 Copenhagen V, Denmark.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Starch synthase IA633Hordeum vulgareMutation(s): 0 
Gene Names: SSIglgA2
EC: 2.4.1.21 (PDB Primary Data), 2.4.1 (UniProt)
Find proteins for Q9M5A3 (Hordeum vulgare)
Explore Q9M5A3 
Go to UniProtKB:  Q9M5A3
Protein Feature View
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  • Reference Sequence
Oligosaccharides

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Entity ID: 2
MoleculeChainsChain Length2D Diagram Glycosylation
alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose
B
5 N/A
Biologically Interesting Molecules (External Reference) 1 Unique
Entity ID: 2
IDChainsNameType/Class2D Diagram3D Interactions
PRD_900030
Query on PRD_900030
Balpha-maltopentaoseOligosaccharide /  Substrate analog

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Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.174 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 153.15α = 90
b = 153.15β = 90
c = 84.96γ = 120
Software Package:
Software NamePurpose
ADSCdata collection
PHASERphasing
PHENIXrefinement
XDSdata reduction
XDSdata scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-06-05
    Type: Initial release
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Atomic model, Data collection, Database references, Derived calculations, Structure summary