Crystal structure of a methyltransferase (NP_951602.1) from Geobacter sulfurreducens at 1.90 A resolution

Joint Center for Structural Genomics (JCSG)

Adjustable focusing mirrors in K-B geometry

TWO CRYSTALS WERE USED FOR THE SOLUTION OF THIS STRUCTURE. A 2.4 ANGSTROM MAD DATA SET COLLECTED FROM ONE CRYSTAL WAS USED TO PHASE AND TRACE AN INITIAL MODEL. THE MODEL WAS THEN REFINED USING THE AMPLITUDES FROM A SECOND CRYSTAL THAT DIFFRACTED TO AN ENHANCED RESOLUTION OF 1.9 ANGSTROM. THE 2.4 ANGSTROM MAD PHASES FROM THE FIRST CRYSTAL WERE USED AS PHASE RESTRAINTS DURING THE REFINEMENT.

NANODROP, 0.2M Sodium chloride, 18.0% PEG 8000, 0.1M CAPS pH 10.3, VAPOR DIFFUSION, SITTING DROP, temperature 277K

NANODROP, 0.2M Sodium chloride, 20.0% PEG 8000, 0.1M CAPS pH 10.5, VAPOR DIFFUSION, SITTING DROP, temperature 277K

THE CONSTRUCT WAS EXPRESSED WITH A PURIFICATION TAG MGSDKIHHHHHHENLYFQG. THE TAG WAS REMOVED WITH TEV PROTEASE LEAVING ONLY A GLYCINE FOLLOWED BY THE TARGET SEQUENCE.

1. HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS.
2. A MET-INHIBITION PROTOCOL WAS USED FOR SELENOMETHIONINE
INCORPORATION DURING PROTEIN EXPRESSION. THE OCCUPANCY
OF THE SE ATOMS IN THE MSE RESIDUES WAS REDUCED TO
0.75 TO ACCOUNT FOR THE REDUCED SCATTERING POWER DUE TO
PARTIAL S-MET INCORPORATION.
3. ATOM RECORD CONTAINS RESIDUAL B FACTORS ONLY.
4. 1,2-ETHANEDIOL, CHLORIDE AND PEG MOLECULES FROM THE
CRYSTALLIZATION CONDITIONS HAVE BEEN MODELED IN THE SOLVENT
STRUCTURE.
5. AMINO ACID LEU178 IN CHAIN A IS A RAMACHANDRAN OUTLIER
AND IS IN A REGION OF WEAK ELECTRON DENSITY.

CRYSTAL PACKING ANALYSIS AND SIZE EXCLUSION CHROMATOGRAPHY SUPPORT THE ASSIGNMENT OF A DIMER AS THE SIGNIFICANT OLIGOMERIZATION STATE.

NP_951602.1, O-Methyltransferase, Structural Genomics, Joint Center for Structural Genomics, JCSG, Protein Structure Initiative, PSI-2, TRANSFERASE