Biological Assembly 1  

 3D View: Structure | Electron Density | Ligand Interaction

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 50.88 kDa 
• Atom Count: 3848 
• Residue Count: 492 
• Unique protein chains: 1

4KH3

Structure of a bacterial self-associating protein

• DOI: 10.2210/pdb4KH3/pdb

• Classification: IMMUNE SYSTEM
• Organism(s): Escherichia coli CFT073
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 2013-04-30 Released: 2014-01-15 
• Deposition Author(s): Heras, B., Gee, C.L., Schembri, M.A., Totsika, M.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.50 Å
• R-Value Free: 0.216 
• R-Value Work: 0.168 
• R-Value Observed: 0.172 

Literature

The antigen 43 structure reveals a molecular Velcro-like mechanism of autotransporter-mediated bacterial clumping.

Heras, B., Totsika, M., Peters, K.M., Paxman, J.J., Gee, C.L., Jarrott, R.J., Perugini, M.A., Whitten, A.E., Schembri, M.A.

(2014) Proc Natl Acad Sci U S A 111: 457-462

• PubMed: 24335802 
• DOI: 10.1073/pnas.1311592111
• Primary Citation of Related Structures:  
  4KH3


• PubMed Abstract: 
  

Aggregation and biofilm formation are critical mechanisms for bacterial resistance to host immune factors and antibiotics. Autotransporter (AT) proteins, which represent the largest group of outer-membrane and secreted proteins in Gram-negative bacteria, contribute significantly to these phenotypes. Despite their abundance and role in bacterial pathogenesis, most AT proteins have not been structurally characterized, and there is a paucity of detailed information with regard to their mode of action. Here we report the structure-function relationships of Antigen 43 (Ag43a), a prototypic self-associating AT protein from uropathogenic Escherichia coli. The functional domain of Ag43a displays a twisted L-shaped β-helical structure firmly stabilized by a 3D hydrogen-bonded scaffold. Notably, the distinctive Ag43a L shape facilitates self-association and cell aggregation. Combining all our data, we define a molecular "Velcro-like" mechanism of AT-mediated bacterial clumping, which can be tailored to fit different bacterial lifestyles such as the formation of biofilms.

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Organizational Affiliation: 

Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Antigen 43	A	503	Escherichia coli CFT073	Mutation(s): 0  Gene Names: agn43, c3655
Find proteins for A0A0H2VAW5 (Escherichia coli O6:H1 (strain CFT073 / ATCC 700928 / UPEC)) Explore A0A0H2VAW5  Go to UniProtKB:  A0A0H2VAW5

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
MLI	A	MALONATE ION C3 H2 O4 OFOBLEOULBTSOW-UHFFFAOYSA-L

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.50 Å
• R-Value Free: 0.216 
• R-Value Work: 0.168 
• R-Value Observed: 0.172 
• Space Group: P 4 2₁ 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 106.045	α = 90
b = 106.045	β = 90
c = 147.545	γ = 90

Software Package:

Software Name	Purpose
Blu-Ice	data collection
SOLVE	phasing
PHENIX	refinement
XDS	data reduction
SCALA	data scaling

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2013-04-30 
• Released Date: 2014-01-15 
Deposition Author(s): Heras, B., Gee, C.L., Schembri, M.A., Totsika, M.

Revision History 

• Version 1.0: 2014-01-15
  Type: Initial release
  
• Version 1.1: 2014-02-05
  Changes: Derived calculations
• Version 1.2: 2015-06-17
  Changes: Database references