Crystal Structure of the periplasmic alginate lyase AlgL

Experimental Data Snapshot

  • Resolution: 1.64 Å
  • R-Value Free: 0.194 
  • R-Value Work: 0.177 
  • R-Value Observed: 0.177 

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The Pseudomonas aeruginosa homeostasis enzyme AlgL clears the periplasmic space of accumulated alginate during polymer biosynthesis.

Gheorghita, A.A.Wolfram, F.Whitfield, G.B.Jacobs, H.M.Pfoh, R.Wong, S.S.Y.Guitor, A.K.Goodyear, M.C.Berezuk, A.M.Khursigara, C.M.Parsek, M.R.Howell, P.L.

(2022) J Biol Chem 298: 101560-101560

  • DOI: https://doi.org/10.1016/j.jbc.2021.101560
  • Primary Citation of Related Structures:  
    4OZV, 4OZW, 7SA8

  • PubMed Abstract: 

    Pseudomonas aeruginosa is an opportunistic human pathogen and a leading cause of chronic infection in the lungs of individuals with cystic fibrosis. After colonization, P. aeruginosa often undergoes a phenotypic conversion to mucoidy, characterized by overproduction of the alginate exopolysaccharide. This conversion is correlated with poorer patient prognoses. The majority of genes required for alginate synthesis, including the alginate lyase, algL, are located in a single operon. Previous investigations of AlgL have resulted in several divergent hypotheses regarding the protein's role in alginate production. To address these discrepancies, we determined the structure of AlgL and, using multiple sequence alignments, identified key active site residues involved in alginate binding and catalysis. In vitro enzymatic analysis of active site mutants highlights R249 and Y256 as key residues required for alginate lyase activity. In a genetically engineered P. aeruginosa strain where alginate biosynthesis is under arabinose control, we found that AlgL is required for cell viability and maintaining membrane integrity during alginate production. We demonstrate that AlgL functions as a homeostasis enzyme to clear the periplasmic space of accumulated polymer. Constitutive expression of the AlgU/T sigma factor mitigates the effects of an algL deletion during alginate production, suggesting that an AlgU/T-regulated protein or proteins can compensate for an algL deletion. Together, our study demonstrates the role of AlgL in alginate biosynthesis, explains the discrepancies observed previously across other P. aeruginosa ΔalgL genetic backgrounds, and clarifies the existing divergent data regarding the function of AlgL as an alginate degrading enzyme.

  • Organizational Affiliation

    Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Alginate lyase335Pseudomonas aeruginosa PAO1Mutation(s): 0 
Gene Names: algLPA3547
Find proteins for Q06749 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Explore Q06749 
Go to UniProtKB:  Q06749
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ06749
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on BEM

Download Ideal Coordinates CCD File 
B [auth A]beta-D-mannopyranuronic acid
C6 H10 O7
Experimental Data & Validation

Experimental Data

  • Resolution: 1.64 Å
  • R-Value Free: 0.194 
  • R-Value Work: 0.177 
  • R-Value Observed: 0.177 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 56.384α = 90
b = 59.576β = 90
c = 102.096γ = 90
Software Package:
Software NamePurpose
SCALEPACKdata scaling
HKL-2000data reduction
PDB_EXTRACTdata extraction

Structure Validation

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Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Canadian Institutes of Health Research (CIHR)Canada--

Revision History  (Full details and data files)

  • Version 1.0: 2015-03-04
    Type: Initial release
  • Version 1.1: 2017-09-27
    Changes: Author supporting evidence, Database references, Derived calculations, Other, Source and taxonomy, Structure summary
  • Version 1.2: 2020-01-08
    Changes: Author supporting evidence
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Refinement description, Structure summary
  • Version 2.1: 2022-08-03
    Changes: Database references, Structure summary