The structure a AS-48 G13K/L40K mutant

Experimental Data Snapshot

  • Resolution: 1.20 Å
  • R-Value Free: 0.147 
  • R-Value Work: 0.118 
  • R-Value Observed: 0.120 

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The bacteriocin AS-48 requires dimer dissociation followed by hydrophobic interactions with the membrane for antibacterial activity.

Cebrian, R.Martinez-Bueno, M.Valdivia, E.Albert, A.Maqueda, M.Sanchez-Barrena, M.J.

(2015) J Struct Biol 190: 162-172

  • DOI: https://doi.org/10.1016/j.jsb.2015.03.006
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The molecular mechanism underlining the antibacterial activity of the bacteriocin AS-48 is not known, and two different and opposite alternatives have been proposed. Available data suggested that the interaction of positively charged amino acids of AS-48 with the membrane would produce membrane destabilization and disruption. Alternatively, it has been proposed that AS-48 activity could rely on the effective insertion of the bacteriocin into the membrane. The biological and structural properties of the AS-48G13K/L40K double mutant were investigated to shed light on this subject. Compared with the wild type, the mutant protein suffered an important reduction in the antibacterial activity. Biochemical and structural studies of AS-48G13K/L40K mutant suggest the basis of its decreased antimicrobial activity. Lipid cosedimentation assays showed that the membrane affinity of AS-48G13K/L40K is 12-fold lower than that observed for the wild type. L40K mutation is responsible for this reduced membrane affinity and thus, hydrophobic interactions are involved in membrane association. Furthermore, the high-resolution crystal structure of AS-48G13K/L40K, together with the study of its dimeric character in solution showed that G13K stabilizes the inactive water-soluble dimer, which displays a reduced dipole moment. Our data suggest that the cumulative effect of these three affected properties reduces AS-48 activity, and point out that the bactericidal effect is achieved by the electrostatically driven approach of the inactive water-soluble dimer towards the membrane, followed by the dissociation and insertion of the protein into the lipid bilayer.

  • Organizational Affiliation

    Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Spain.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Bacteriocin AS-48
A, B
70Enterococcus faecalisMutation(s): 2 
Gene Names: as-48as48A
Find proteins for Q47765 (Enterococcus faecalis)
Explore Q47765 
Go to UniProtKB:  Q47765
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ47765
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on CIT

Download Ideal Coordinates CCD File 
C6 H8 O7
Experimental Data & Validation

Experimental Data

  • Resolution: 1.20 Å
  • R-Value Free: 0.147 
  • R-Value Work: 0.118 
  • R-Value Observed: 0.120 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 32.82α = 90
b = 49.91β = 98.16
c = 41.72γ = 90
Software Package:
Software NamePurpose
DNAdata collection
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-04-15
    Type: Initial release
  • Version 1.1: 2015-08-26
    Changes: Database references
  • Version 1.2: 2023-09-20
    Changes: Data collection, Database references, Derived calculations, Refinement description