3HBB

Structures of dihydrofolate reductase-thymidylate synthase of Trypanosoma cruzi in the folate-free state and in complex with two antifolate drugs, trimetrexate and methotrexate

X-RAY DIFFRACTION

Starting Model(s)

Initial Refinement Model(s)
Type	Source	Accession Code	Details
experimental model	PDB	2H2Q	2H2Q, chain A

Crystallization

Crystalization Experiments
ID	Method	pH	Temperature	Details
1	VAPOR DIFFUSION, HANGING DROP	7.5	295	1.5-1.7 M ammonium sulfate, 0.01 M magnesium chloride, 5% ethylene glycol and 0.05 M Tris, pH 7.5, VAPOR DIFFUSION, HANGING DROP, temperature 295K

Crystal Properties
Matthews coefficient	Solvent content
4.17	70.47

Crystal Data

Unit Cell
Length ( Å )	Angle ( ˚ )
a = 176.571	α = 90
b = 176.571	β = 90
c = 251.848	γ = 90

Symmetry
Space Group	P 43 21 2

Diffraction

Diffraction Experiment
ID #	Crystal ID	Scattering Type	Data Collection Temperature	Detector	Detector Type	Details	Collection Date	Monochromator	Protocol
1	1	x-ray	100	CCD	MAR CCD 165 mm	mirrors	2006-08-15	M	SINGLE WAVELENGTH

Radiation Source
ID #	Source	Type	Wavelength List	Synchrotron Site	Beamline
1	SYNCHROTRON	APS BEAMLINE 17-ID	1.0	APS	17-ID

Data Collection

Overall
ID #	Resolution (High)	Resolution (Low)	Percent Possible (Observed)	R Merge I (Observed)	R Sym I (Observed)	Net I Over Average Sigma (I)	Redundancy	Number Reflections (All)	Number Reflections (Observed)	Observed Criterion Sigma (F)	Observed Criterion Sigma (I)	B (Isotropic) From Wilson Plot
1	3	24.97	97.2	0.152	0.152	7.9	6.7	77643	77643	1	1	54

Highest Resolution Shell
ID #	Resolution (High)	Resolution (Low)	Percent Possible (All)	Percent Possible (Observed)	R Merge I (Observed)	R-Sym I (Observed)	Mean I Over Sigma (Observed)	Redundancy	Number Unique Reflections (All)
1	3	3.11	98.3		0.472	0.472	3	6.8	7755

Refinement

Statistics
Diffraction ID	Structure Solution Method	Cross Validation method	Starting model	Resolution (High)	Resolution (Low)	Number Reflections (All)	Number Reflections (Observed)	Number Reflections (R-Free)	Percent Reflections (Observed)	R-Factor (All)	R-Factor (Observed)	R-Work	R-Free	R-Free Selection Details	Mean Isotropic B
X-RAY DIFFRACTION	MOLECULAR REPLACEMENT	THROUGHOUT	2H2Q, chain A	3	19.94	73568	73568	3898	97.14	0.203	0.203	0.20112	0.23885	RANDOM	38.7

Temperature Factor Modeling
Anisotropic B[1][1]	Anisotropic B[1][2]	Anisotropic B[1][3]	Anisotropic B[2][2]	Anisotropic B[2][3]	Anisotropic B[3][3]
0.37			0.37		-0.74

RMS Deviations
Key	Refinement Restraint Deviation
r_dihedral_angle_2_deg	33.956
r_dihedral_angle_4_deg	17.837
r_dihedral_angle_3_deg	17.785
r_dihedral_angle_1_deg	5.578
r_scangle_it	1.336
r_angle_refined_deg	1.137
r_scbond_it	0.752
r_mcangle_it	0.645
r_mcbond_it	0.336
r_chiral_restr	0.074

RMS Deviations
Key	Refinement Restraint Deviation
r_dihedral_angle_2_deg	33.956
r_dihedral_angle_4_deg	17.837
r_dihedral_angle_3_deg	17.785
r_dihedral_angle_1_deg	5.578
r_scangle_it	1.336
r_angle_refined_deg	1.137
r_scbond_it	0.752
r_mcangle_it	0.645
r_mcbond_it	0.336
r_chiral_restr	0.074
r_bond_refined_d	0.007
r_gen_planes_refined	0.004

Non-Hydrogen Atoms Used in Refinement
Non-Hydrogen Atoms	Number
Protein Atoms	16134
Nucleic Acid Atoms
Solvent Atoms	190
Heterogen Atoms	488

Software

Software
Software Name	Purpose
HKL-2000	data collection
PHASER	phasing
REFMAC	refinement
d*TREK	data reduction
d*TREK	data scaling

RCSB PDB Core Operations are funded by the U.S. National Science Foundation (DBI-2321666), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM157729.