1LL6

STRUCTURE OF THE D169N MUTANT OF C. IMMITIS CHITINASE 1


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.182 

wwPDB Validation 3D Report Full Report


This is version 1.2 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, 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 ...

    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

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CHITINASE 1
A, B, C, D
392Coccidioides posadasii (strain RMSCC 757 / Silveira)Gene Names: CTS1
EC: 3.2.1.14
Find proteins for P0CB51 (Coccidioides posadasii (strain RMSCC 757 / Silveira))
Go to UniProtKB:  P0CB51
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.182 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 60.890α = 80.51
b = 78.180β = 82.13
c = 88.430γ = 66.99
Software Package:
Software NamePurpose
X-PLORrefinement
SCALEPACKdata scaling
DENZOdata reduction
X-PLORphasing
X-PLORmodel building

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2002-12-18
    Type: Initial release
  • Version 1.1: 2008-04-28
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance