5I7L

Crystal Structure of SPLUNC1 Disulfide Mutant M2 (A48C, V253C)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.598 Å
  • R-Value Free: 0.284 
  • R-Value Work: 0.220 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structural Features Essential to the Antimicrobial Functions of Human SPLUNC1.

Walton, W.G.Ahmad, S.Little, M.S.Kim, C.S.Tyrrell, J.Lin, Q.Di, Y.P.Tarran, R.Redinbo, M.R.

(2016) Biochemistry 55: 2979-2991

  • DOI: 10.1021/acs.biochem.6b00271
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • SPLUNC1 is an abundantly secreted innate immune protein in the mammalian respiratory tract that exerts bacteriostatic and antibiofilm effects, binds to lipopolysaccharide (LPS), and acts as a fluid-spreading surfactant. Here, we unravel the structura ...

    SPLUNC1 is an abundantly secreted innate immune protein in the mammalian respiratory tract that exerts bacteriostatic and antibiofilm effects, binds to lipopolysaccharide (LPS), and acts as a fluid-spreading surfactant. Here, we unravel the structural elements essential for the surfactant and antimicrobial functions of human SPLUNC1 (short palate lung nasal epithelial clone 1). A unique α-helix (α4) that extends from the body of SPLUNC1 is required for the bacteriostatic, surfactant, and LPS binding activities of this protein. Indeed, we find that mutation of just four leucine residues within this helical motif to alanine is sufficient to significantly inhibit the fluid spreading abilities of SPLUNC1, as well as its bacteriostatic actions against Gram-negative pathogens Burkholderia cenocepacia and Pseudomonas aeruginosa. Conformational flexibility in the body of SPLUNC1 is also involved in the bacteriostatic, surfactant, and LPS binding functions of the protein as revealed by disulfide mutants introduced into SPLUNC1. In addition, SPLUNC1 exerts antibiofilm effects against Gram-negative bacteria, although α4 is not involved in this activity. Interestingly, though, the introduction of surface electrostatic mutations away from α4 based on the unique dolphin SPLUNC1 sequence, and confirmed by crystal structure, is shown to impart antibiofilm activity against Staphylococcus aureus, the first SPLUNC1-dependent effect against a Gram-positive bacterium reported to date. Together, these data pinpoint SPLUNC1 structural motifs required for the antimicrobial and surfactant actions of this protective human protein.


    Organizational Affiliation

    Departments of Chemistry, Biochemistry, and Microbiology, University of North Carolina , 4350 Genome Sciences Building, Chapel Hill, North Carolina 27599-3290, United States.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
BPI fold-containing family A member 1
A, B
240Homo sapiensMutation(s): 2 
Gene Names: BPIFA1 (LUNX, NASG, PLUNC, SPLUNC1, SPURT)
Find proteins for Q9NP55 (Homo sapiens)
Go to Gene View: BPIFA1
Go to UniProtKB:  Q9NP55
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.598 Å
  • R-Value Free: 0.284 
  • R-Value Work: 0.220 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 47.083α = 90.00
b = 203.588β = 90.00
c = 120.211γ = 90.00
Software Package:
Software NamePurpose
PHENIXrefinement
SCALEPACKdata scaling
DENZOdata reduction
PHASERphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Heart, Lung, and Blood InstituteUnited StatesR01 HL108927

Revision History 

  • Version 1.0: 2016-05-18
    Type: Initial release
  • Version 1.1: 2016-06-08
    Type: Database references
  • Version 1.2: 2017-09-20
    Type: Author supporting evidence, Database references, Derived calculations