7U0U

Crystal Structure of a Aspergillus fumigatus Calcineurin A - Calcineurin B fusion bound to FKBP12 and FK-506


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.171 

wwPDB Validation   3D Report Full Report


Ligand Structure Quality Assessment 


This is version 1.1 of the entry. See complete history


Literature

Structure-Guided Synthesis of FK506 and FK520 Analogs with Increased Selectivity Exhibit In Vivo Therapeutic Efficacy against Cryptococcus.

Hoy, M.J.Park, E.Lee, H.Lim, W.Y.Cole, D.C.DeBouver, N.D.Bobay, B.G.Pierce, P.G.Fox 3rd, D.Ciofani, M.Juvvadi, P.R.Steinbach, W.Hong, J.Heitman, J.

(2022) mBio 13: e0104922-e0104922

  • DOI: https://doi.org/10.1128/mbio.01049-22
  • Primary Citation of Related Structures:  
    7U0S, 7U0T, 7U0U

  • PubMed Abstract: 

    Calcineurin is an essential virulence factor that is conserved across human fungal pathogens, including Cryptococcus neoformans, Aspergillus fumigatus, and Candida albicans. Although an excellent target for antifungal drug development, the serine-threonine phosphatase activity of calcineurin is conserved in mammals, and inhibition of this activity results in immunosuppression. FK506 (tacrolimus) is a naturally produced macrocyclic compound that inhibits calcineurin by binding to the immunophilin FKBP12. Previously, our fungal calcineurin-FK506-FKBP12 structure-based approaches identified a nonconserved region of FKBP12 that can be exploited for fungus-specific targeting. These studies led to the design of an FK506 analog, APX879, modified at the C-22 position, which was less immunosuppressive yet maintained antifungal activity. We now report high-resolution protein crystal structures of fungal FKBP12 and a human truncated calcineurin-FKBP12 bound to a natural FK506 analog, FK520 (ascomycin). Based on information from these structures and the success of APX879, we synthesized and screened a novel panel of C-22-modified compounds derived from both FK506 and FK520. One compound, JH-FK-05, demonstrates broad-spectrum antifungal activity in vitro and is nonimmunosuppressive in vivo . In murine models of pulmonary and disseminated C. neoformans infection, JH-FK-05 treatment significantly reduced fungal burden and extended animal survival alone and in combination with fluconazole. Furthermore, molecular dynamic simulations performed with JH-FK-05 binding to fungal and human FKBP12 identified additional residues outside the C-22 and C-21 positions that could be modified to generate novel FK506 analogs with improved antifungal activity. IMPORTANCE Due to rising rates of antifungal drug resistance and a limited armamentarium of antifungal treatments, there is a paramount need for novel antifungal drugs to treat systemic fungal infections. Calcineurin has been established as an essential and conserved virulence factor in several fungi, making it an attractive antifungal target. However, due to the immunosuppressive action of calcineurin inhibitors, they have not been successfully utilized clinically for antifungal treatment in humans. Recent availability of crystal structures of fungal calcineurin-bound inhibitor complexes has enabled the structure-guided design of FK506 analogs and led to a breakthrough in the development of a compound with increased fungal specificity. The development of a calcineurin inhibitor with reduced immunosuppressive activity and maintained therapeutic antifungal activity would add a significant tool to the treatment options for these invasive fungal infections with exceedingly high rates of mortality.


  • Organizational Affiliation

    Department of Molecular Genetics and Microbiology, Duke Universitygrid.26009.3d Medical Center, Durham, North Carolina, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Serine/threonine-protein phosphatase 2B catalytic subunit,AsfuA.00174.a.TQ11 + AsfuA.01011.a.TR11268Aspergillus fumigatusMutation(s): 0 
Gene Names: cnaAAFUA_5G09360CNMCM8057_008799CNMCM8686_005215
EC: 3.1.3.16
UniProt
Find proteins for Q4WUR1 (Aspergillus fumigatus (strain ATCC MYA-4609 / CBS 101355 / FGSC A1100 / Af293))
Explore Q4WUR1 
Go to UniProtKB:  Q4WUR1
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ4WUR1
Sequence Annotations
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Peptidylprolyl isomerase132Aspergillus fumigatusMutation(s): 1 
Gene Names: CDV57_03547
EC: 5.2.1.8
UniProt
Find proteins for Q4WLV6 (Aspergillus fumigatus (strain ATCC MYA-4609 / CBS 101355 / FGSC A1100 / Af293))
Explore Q4WLV6 
Go to UniProtKB:  Q4WLV6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ4WLV6
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
FK5 (Subject of Investigation/LOI)
Query on FK5

Download Ideal Coordinates CCD File 
I [auth B]8-DEETHYL-8-[BUT-3-ENYL]-ASCOMYCIN
C44 H69 N O12
QJJXYPPXXYFBGM-LFZNUXCKSA-N
PG4
Query on PG4

Download Ideal Coordinates CCD File 
G [auth A]TETRAETHYLENE GLYCOL
C8 H18 O5
UWHCKJMYHZGTIT-UHFFFAOYSA-N
PO4
Query on PO4

Download Ideal Coordinates CCD File 
H [auth A]PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
CA
Query on CA

Download Ideal Coordinates CCD File 
C [auth A],
D [auth A],
E [auth A],
F [auth A]
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

Unit Cell:
Length ( Å )Angle ( ˚ )
a = 75.01α = 90
b = 83.7β = 90
c = 137.58γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
XSCALEdata scaling
PHASERphasing
PHENIXrefinement
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report



Ligand Structure Quality Assessment 


Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Not funded--

Revision History  (Full details and data files)

  • Version 1.0: 2022-08-03
    Type: Initial release
  • Version 1.1: 2023-10-18
    Changes: Data collection, Refinement description