SiaA-PP2C domain of Pseudomonas aeruginosa

Experimental Data Snapshot

  • Resolution: 2.09 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.212 
  • R-Value Observed: 0.213 

wwPDB Validation   3D Report Full Report

This is version 1.3 of the entry. See complete history


The SiaABC threonine phosphorylation pathway controls biofilm formation in response to carbon availability in Pseudomonas aeruginosa.

Poh, W.H.Lin, J.Colley, B.Muller, N.Goh, B.C.Schleheck, D.El Sahili, A.Marquardt, A.Liang, Y.Kjelleberg, S.Lescar, J.Rice, S.A.Klebensberger, J.

(2020) PLoS One 15: e0241019-e0241019

  • DOI: https://doi.org/10.1371/journal.pone.0241019
  • Primary Citation of Related Structures:  
    6K4E, 6K4F

  • PubMed Abstract: 

    The critical role of bacterial biofilms in chronic human infections calls for novel anti-biofilm strategies targeting the regulation of biofilm development. However, the regulation of biofilm development is very complex and can include multiple, highly interconnected signal transduction/response pathways, which are incompletely understood. We demonstrated previously that in the opportunistic, human pathogen P. aeruginosa, the PP2C-like protein phosphatase SiaA and the di-guanylate cyclase SiaD control the formation of macroscopic cellular aggregates, a type of suspended biofilms, in response to surfactant stress. In this study, we demonstrate that the SiaABC proteins represent a signal response pathway that functions through a partner switch mechanism to control biofilm formation. We also demonstrate that SiaABCD functionality is dependent on carbon substrate availability for a variety of substrates, and that upon carbon starvation, SiaB mutants show impaired dispersal, in particular with the primary fermentation product ethanol. This suggests that carbon availability is at least one of the key environmental cues integrated by the SiaABCD system. Further, our biochemical, physiological and crystallographic data reveals that the phosphatase SiaA and its kinase counterpart SiaB balance the phosphorylation status of their target protein SiaC at threonine 68 (T68). Crystallographic analysis of the SiaA-PP2C domain shows that SiaA is present as a dimer. Dynamic modelling of SiaA with SiaC suggested that SiaA interacts strongly with phosphorylated SiaC and dissociates rapidly upon dephosphorylation of SiaC. Further, we show that the known phosphatase inhibitor fumonisin inhibits SiaA mediated phosphatase activity in vitro. In conclusion, the present work improves our understanding of how P. aeuruginosa integrates specific environmental conditions, such as carbon availability and surfactant stress, to regulate cellular aggregation and biofilm formation. With the biochemical and structural characterization of SiaA, initial data on the catalytic inhibition of SiaA, and the interaction between SiaA and SiaC, our study identifies promising targets for the development of biofilm-interference drugs to combat infections of this aggressive opportunistic pathogen.

  • Organizational Affiliation

    Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Putative serine phosphatase
A, B
301Pseudomonas aeruginosaMutation(s): 0 
Gene Names: NCTC11839_02430
Find proteins for Q9I6W0 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Explore Q9I6W0 
Go to UniProtKB:  Q9I6W0
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9I6W0
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.09 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.212 
  • R-Value Observed: 0.213 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 51.17α = 90
b = 110.48β = 90
c = 111.6γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
XDSdata scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2019-06-26
    Type: Initial release
  • Version 1.1: 2019-10-02
    Changes: Data collection, Database references, Source and taxonomy, Structure summary
  • Version 1.2: 2020-11-25
    Changes: Database references, Derived calculations
  • Version 1.3: 2021-11-03
    Changes: Database references, Structure summary