Biological Assembly 1  

 3D View: Structure | Electron Density | Ligand Interaction

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 51.86 kDa 
• Atom Count: 3082 
• Modelled Residue Count: 361 
• Deposited Residue Count: 440 
• Unique protein chains: 1

1TC1

A 1.4 ANGSTROM CRYSTAL STRUCTURE FOR THE HYPOXANTHINE PHOSPHORIBOSYLTRANSFERASE OF TRYPANOSOMA CRUZI

• DOI: 10.2210/pdb1TC1/pdb

• Classification: TRANSFERASE
• Organism(s): Trypanosoma cruzi
• Expression System: Escherichia coli
• Mutation(s): Yes 


• Deposited: 1998-09-30 Released: 1999-10-07 
• Deposition Author(s): Focia, P.J., Craig III, S.P., Nieves-Alicea, R., Fletterick, R.J., Eakin, A.E.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.41 Å
• R-Value Free: 0.228 
• R-Value Work: 0.198 
• R-Value Observed: 0.193 

Literature

A 1.4 A crystal structure for the hypoxanthine phosphoribosyltransferase of Trypanosoma cruzi.

Focia, P.J., Craig III, S.P., Nieves-Alicea, R., Fletterick, R.J., Eakin, A.E.

(1998) Biochemistry 37: 15066-15075

• PubMed: 9790669 
• DOI: 10.1021/bi981052s
• Primary Citation of Related Structures:  
  1TC1


• PubMed Abstract: 
  

The hypoxanthine phosphoribosyltransferase (HPRT) from Trypanosoma cruzi, etiologic agent of Chagas' disease, was cocrystallized with the inosine analogue Formycin B (FmB) and the structure determined to 1.4 A resolution. This is the highest resolution structure yet reported for a phosphoribosyltransferase (PRT), and the asymmetric unit of the crystal contains a dimer of closely associated, nearly identical subunits. A conserved nonproline cis peptide in one active-site loop exposes the main-chain nitrogen to the enzyme active site, while the adjacent lysine side chain interacts with the other subunit of the dimer, thereby providing a possible mechanism for communication between the subunits and their active sites. The three-dimensional coordinates for the invariant Ser103-Tyr104 dipeptide are reported here for the first time. These are the only highly conserved residues in a second active-site loop, termed the long flexible loop, which is predicted to close over the active site of HPRTs to protect a labile transition state [Eads et al. (1994) Cell 78, 325-334]. This structure represents a major step forward in efforts to design/discover potent selective inhibitors of the HPRT of T. cruzi.

---

Organizational Affiliation: 

Laboratory of Molecular Parasitology & Drug Design, School of Pharmacy, University of North Carolina, Chapel Hill 27599-7360, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
PROTEIN (HYPOXANTHINE PHOSPHORIBOSYLTRANSFERASE)	A, B	220	Trypanosoma cruzi	Mutation(s): 3  EC: 2.4.2.8
Find proteins for Q4DRC4 (Trypanosoma cruzi (strain CL Brener)) Explore Q4DRC4  Go to UniProtKB:  Q4DRC4

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
FMB	C [auth A], E [auth B]	FORMYCIN B C10 H12 N4 O5 MTCJZZBQNCXKAP-KSYZLYKTSA-N
MES	D [auth A], F [auth B]	2-(N-MORPHOLINO)-ETHANESULFONIC ACID C6 H13 N O4 S SXGZJKUKBWWHRA-UHFFFAOYSA-N

External Ligand Annotations
ID	Binding Affinity (Sequence Identity %)
FMB	IC50 :  2000000   nM  PDBBind
FMB	IC50:  2000000   nM  Binding MOAD

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.41 Å
• R-Value Free: 0.228 
• R-Value Work: 0.198 
• R-Value Observed: 0.193 
• Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 39.5	α = 90
b = 94.09	β = 94.75
c = 52.12	γ = 90

Software Package:

Software Name	Purpose
AMoRE	phasing
X-PLOR	refinement
DENZO	data reduction
SCALEPACK	data scaling

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 1998-09-30 
• Released Date: 1999-10-07 
Deposition Author(s): Focia, P.J., Craig III, S.P., Nieves-Alicea, R., Fletterick, R.J., Eakin, A.E.

Revision History  

• Version 1.0: 1999-10-07
  Type: Initial release
  
• Version 1.1: 2008-04-27
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2018-01-24
  Changes: Database references
• Version 1.4: 2018-01-31
  Changes: Database references