1LL7

STRUCTURE OF THE E171Q MUTANT OF C. IMMITIS CHITINASE 1


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.267 
  • R-Value Work: 0.207 

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This is version 1.3 of the entry. See complete history


Literature

THE STRUCTURE OF AN ALLOSAMIDIN COMPLEX WITH THE COCCIDIOIDES IMMITIS CHITINASE DEFINES A ROLE FOR A SECOND ACID RESIDUE IN SUBSTRATE-ASSISTED MECHANISM

BORTONE, K.MONZINGO, A.F.ERNST, S.ROBERTUS, J.D.

(2002) J Mol Biol 320: 293-302

  • DOI: 10.1016/S0022-2836(02)00444-8
  • Primary Citation of Related Structures:  
    1LL4, 1LL6, 1LL7

  • PubMed Abstract: 
  • Allosamidin is a known inhibitor of class 18 chitinases. We show that allosamidin is a competitive inhibitor of the fungal chitinase CiX1 from Coccidioides immitis, with a K(i) of 60 nM. We report the X-ray structure of the complex and show that upon inhibitor binding the side-chain of Asp169 rotates to form an ion pair with the oxazolinium cation ...

    Allosamidin is a known inhibitor of class 18 chitinases. We show that allosamidin is a competitive inhibitor of the fungal chitinase CiX1 from Coccidioides immitis, with a K(i) of 60 nM. We report the X-ray structure of the complex and show that upon inhibitor binding the side-chain of Asp169 rotates to form an ion pair with the oxazolinium cation. The mechanism of action is thought to involve protonation of the leaving group by Glu171 and substrate assistance by the sugar acetamido moiety to form an oxazoline-like intermediate. We converted both amino acid residues to the corresponding amide and found that each mutation effectively abolishes enzyme activity. X-ray structures show the mutant enzymes retain the basic wild-type structure and that the loss of mutant activity is due to their altered chemical properties. The high affinity of allosamidin, and its similarity to the putative reaction intermediate, suggests it is a transition state analog. This helps validate our contention that the role of Asp169 is to electrostatically stabilize the reaction transition state.


    Organizational Affiliation

    Institute of Cellular and Molecular Biology, Department of Chemistry and Biochemistry, University of Texas, Austin, TX 78712, USA.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
CHITINASE 1A, B392Coccidioides immitisMutation(s): 1 
Gene Names: CTS1
EC: 3.2.1.14
UniProt
Find proteins for P0CB51 (Coccidioides posadasii (strain RMSCC 757 / Silveira))
Explore P0CB51 
Go to UniProtKB:  P0CB51
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0CB51
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.267 
  • R-Value Work: 0.207 
  • Space Group: P 43
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 90.33α = 90
b = 90.33β = 90
c = 95.63γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
X-PLORmodel building
X-PLORrefinement
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-12-18
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-10-27
    Changes: Database references