8WG2

Crystal structure of GH97 glucodextranase mutant E509Q from Flavobacterium johnsoniae in complex with isomaltotriose


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.45 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.187 

Starting Model: experimental
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Literature

Structural insights into alpha-(1→6)-linkage preference of GH97 glucodextranase from Flavobacterium johnsoniae.

Nakamura, S.Kurata, R.Miyazaki, T.

(2024) FEBS J 291: 3267-3282

  • DOI: https://doi.org/10.1111/febs.17139
  • Primary Citation of Related Structures:  
    8WG0, 8WG1, 8WG2

  • PubMed Abstract: 

    Glycoside hydrolase family 97 (GH97) comprises enzymes like anomer-inverting α-glucoside hydrolases (i.e., glucoamylase) and anomer-retaining α-galactosidases. In a soil bacterium, Flavobacterium johnsoniae, we previously identified a GH97 enzyme (FjGH97A) within the branched dextran utilization locus. It functions as an α-glucoside hydrolase, targeting α-(1→6)-glucosidic linkages in dextran and isomaltooligosaccharides (i.e., glucodextranase). FjGH97A exhibits a preference for α-(1→6)-glucoside linkages over α-(1→4)-linkages, while Bacteroides thetaiotaomicron glucoamylase SusB (with 69% sequence identity), which is involved in the starch utilization system, exhibits the highest specificity for α-(1→4)-glucosidic linkages. Here, we examined the crystal structures of FjGH97A in complexes with glucose, panose, or isomaltotriose, and analyzed the substrate preferences of its mutants to identify the amino acid residues that determine the substrate specificity for α-(1→4)- and α-(1→6)-glucosidic linkages. The overall structure of FjGH97A resembles other GH97 enzymes, with conserved catalytic residues similar to anomer-inverting GH97 enzymes. A comparison of active sites between FjGH97A and SusB revealed differences in amino acid residues at subsites +1 and +2 (specifically Ala195 and Ile378 in FjGH97A). Among the three mutants (A195S, I378F, and A195S-I378F), A195S and A195S-I378F exhibited increased activity toward α-(1→4)-glucoside bonds compared to α-(1→6)-glucoside bonds. This suggests that Ala195, located on the Gly184-Thr203 loop (named loop-N) conserved within the GH97 subgroup, including FjGH97A and SusB, holds significance in determining linkage specificity. The conservation of alanine in the active site of the GH97 enzymes, within the same gene cluster as the putative dextranase, indicates its crucial role in determining the specificity for α-(1→6)-glucoside linkage.


  • Organizational Affiliation

    Department of Bioscience, Graduate School of Science and Technology, Shizuoka University, Japan.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Candidate alpha-glucosidase Glycoside hydrolase family 97
A, B, C, D
685Flavobacterium johnsoniae UW101Mutation(s): 1 
Gene Names: Fjoh_4429
EC: 3.2.1.70
UniProt
Find proteins for A5FBI0 (Flavobacterium johnsoniae (strain ATCC 17061 / DSM 2064 / JCM 8514 / BCRC 14874 / CCUG 350202 / NBRC 14942 / NCIMB 11054 / UW101))
Explore A5FBI0 
Go to UniProtKB:  A5FBI0
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA5FBI0
Sequence Annotations
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  • Reference Sequence
Oligosaccharides

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Entity ID: 2
MoleculeChains Length2D Diagram Glycosylation3D Interactions
alpha-D-glucopyranose-(1-6)-alpha-D-glucopyranose-(1-6)-alpha-D-glucopyranose
E, H
3N/A
Glycosylation Resources
GlyTouCan:  G02998EX
GlyCosmos:  G02998EX
GlyGen:  G02998EX
Entity ID: 3
MoleculeChains Length2D Diagram Glycosylation3D Interactions
alpha-D-glucopyranose-(1-6)-alpha-D-glucopyranose-(1-6)-beta-D-glucopyranose
F, G
3N/A
Glycosylation Resources
GlyTouCan:  G10488WF
GlyCosmos:  G10488WF
GlyGen:  G10488WF
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.45 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.187 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 308.21α = 90
b = 103.62β = 90
c = 95.75γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
XDSdata reduction
Aimlessdata scaling
MOLREPphasing

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Japan Society for the Promotion of Science (JSPS)Japan23K05039
Japan Society for the Promotion of Science (JSPS)Japan19K15748

Revision History  (Full details and data files)

  • Version 1.0: 2024-05-08
    Type: Initial release
  • Version 1.1: 2024-07-31
    Changes: Database references