Structure of PL24 family Polysaccharide lyase-LOR107

Experimental Data Snapshot

  • Resolution: 1.90 Å
  • R-Value Free: 0.202 
  • R-Value Work: 0.175 
  • R-Value Observed: 0.176 

wwPDB Validation   3D Report Full Report

This is version 1.4 of the entry. See complete history


Structure-function analyses of a PL24 family ulvan lyase reveal key features and suggest its catalytic mechanism.

Ulaganathan, T.Helbert, W.Kopel, M.Banin, E.Cygler, M.

(2018) J Biol Chem 293: 4026-4036

  • DOI: https://doi.org/10.1074/jbc.RA117.001642
  • Primary Citation of Related Structures:  
    6BYP, 6BYT, 6BYX

  • PubMed Abstract: 

    Ulvan is a major cell wall component of green algae of the genus Ulva , and some marine bacteria encode enzymes that can degrade this polysaccharide. The first ulvan-degrading lyases have been recently characterized, and several putative ulvan lyases have been recombinantly expressed, confirmed as ulvan lyases, and partially characterized. Two families of ulvan-degrading lyases, PL24 and PL25, have recently been established. The PL24 lyase LOR_107 from the bacterial Alteromonadales sp. strain LOR degrades ulvan endolytically, cleaving the bond at the C4 of a glucuronic acid. However, the mechanism and LOR_107 structural features involved are unknown. We present here the crystal structure of LOR_107, representing the first PL24 family structure. We found that LOR_107 adopts a seven-bladed β-propeller fold with a deep canyon on one side of the protein. Comparative sequence analysis revealed a cluster of conserved residues within this canyon, and site-directed mutagenesis disclosed several residues essential for catalysis. We also found that LOR_107 uses the His/Tyr catalytic mechanism, common to several PL families. We captured a tetrasaccharide substrate in the structures of two inactive mutants, which indicated a two-step binding event, with the first substrate interaction near the top of the canyon coordinated by Arg 320 , followed by sliding of the substrate into the canyon toward the active-site residues. Surprisingly, the LOR_107 structure was very similar to that of the PL25 family PLSV_3936, despite only ∼14% sequence identity between the two enzymes. On the basis of our structural and mutational analyses, we propose a catalytic mechanism for LOR_107 that differs from the typical His/Tyr mechanism.

  • Organizational Affiliation

    From the Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Short ulvan lyase
A, B
516Alteromonas sp. LORMutation(s): 0 
Gene Names: LOR_107
Find proteins for A0A109PTH9 (Alteromonas sp. (strain LOR))
Explore A0A109PTH9 
Go to UniProtKB:  A0A109PTH9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A109PTH9
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on PEG

Download Ideal Coordinates CCD File 
C4 H10 O3
Query on SO4

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E [auth A]
F [auth A]
G [auth A]
H [auth A]
I [auth A]
E [auth A],
F [auth A],
G [auth A],
H [auth A],
I [auth A],
J [auth A],
K [auth A],
L [auth A],
R [auth B],
S [auth B],
T [auth B],
U [auth B],
V [auth B],
W [auth B]
O4 S
Query on GOL

Download Ideal Coordinates CCD File 
M [auth A],
N [auth A],
O [auth A],
X [auth B],
Y [auth B]
C3 H8 O3
Query on CA

Download Ideal Coordinates CCD File 
C [auth A],
D [auth A],
P [auth B],
Q [auth B]
Experimental Data & Validation

Experimental Data

  • Resolution: 1.90 Å
  • R-Value Free: 0.202 
  • R-Value Work: 0.175 
  • R-Value Observed: 0.176 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 83.551α = 90
b = 121.263β = 90
c = 123.811γ = 90
Software Package:
Software NamePurpose
XDSdata scaling
Cootmodel building
XDSdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2018-02-07
    Type: Initial release
  • Version 1.1: 2018-02-14
    Changes: Database references
  • Version 1.2: 2018-05-02
    Changes: Data collection, Database references
  • Version 1.3: 2019-04-24
    Changes: Author supporting evidence, Data collection
  • Version 1.4: 2024-03-13
    Changes: Data collection, Database references, Derived calculations