3EJW

Crystal Structure of the Sinorhizobium meliloti AI-2 receptor, SmLsrB


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.168 
  • R-Value Observed: 0.170 

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Literature

Sinorhizobium meliloti, a bacterium lacking the autoinducer-2 (AI-2) synthase, responds to AI-2 supplied by other bacteria.

Pereira, C.S.McAuley, J.R.Taga, M.E.Xavier, K.B.Miller, S.T.

(2008) Mol Microbiol 70: 1223-1235

  • DOI: 10.1111/j.1365-2958.2008.06477.x
  • Primary Citation of Related Structures:  
    3EJW

  • PubMed Abstract: 
  • Many bacterial species respond to the quorum-sensing signal autoinducer-2 (AI-2) by regulating different niche-specific genes. Here, we show that Sinorhizobium meliloti, a plant symbiont lacking the gene for the AI-2 synthase, while not capable of pr ...

    Many bacterial species respond to the quorum-sensing signal autoinducer-2 (AI-2) by regulating different niche-specific genes. Here, we show that Sinorhizobium meliloti, a plant symbiont lacking the gene for the AI-2 synthase, while not capable of producing AI-2 can nonetheless respond to AI-2 produced by other species. We demonstrate that S. meliloti has a periplasmic binding protein that binds AI-2. The crystal structure of this protein (here named SmlsrB) with its ligand reveals that it binds (2R,4S)-2-methyl-2,3,3,4-tetrahydroxytetrahydrofuran (R-THMF), the identical AI-2 isomer recognized by LsrB of Salmonella typhimurium. The gene encoding SmlsrB is in an operon with orthologues of the lsr genes required for AI-2 internalization in enteric bacteria. Accordingly, S. meliloti internalizes exogenous AI-2, and mutants in this operon are defective in AI-2 internalization. S. meliloti does not gain a metabolic benefit from internalizing AI-2, suggesting that AI-2 functions as a signal in S. meliloti. Furthermore, S. meliloti can completely eliminate the AI-2 secreted by Erwinia carotovora, a plant pathogen shown to use AI-2 to regulate virulence. Our findings suggest that S. meliloti is capable of 'eavesdropping' on the AI-2 signalling of other species and interfering with AI-2-regulated behaviours such as virulence.


    Organizational Affiliation

    Bacterial Signaling Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
SmLsrBAB315Sinorhizobium melilotiMutation(s): 0 
Gene Names: AitBRB0590SM_b21016SMb21016
Find proteins for Q926H7 (Rhizobium meliloti (strain 1021))
Explore Q926H7 
Go to UniProtKB:  Q926H7
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PAV
Query on PAV

Download Ideal Coordinates CCD File 
A, B
(2R,4S)-2-methyl-2,3,3,4-tetrahydroxytetrahydrofuran
C5 H10 O5
BVIYGXUQVXBHQS-IUYQGCFVSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.168 
  • R-Value Observed: 0.170 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 57.848α = 90
b = 71.488β = 98.69
c = 68.035γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling
PHASERphasing
PHENIXrefinement
PDB_EXTRACTdata extraction
CrystalCleardata collection

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-12-02
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2018-04-04
    Changes: Data collection
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Derived calculations, Structure summary