|Space Group||P3₂21||enantiomorphic with P3₁21|
|Unit Cell||75 75 133 90 90 120||average|
|ASU Contents||1×BETA + 1×BLIP||protein-protein complex|
|Model Quality||100% identity||Both solved independently|
The case of β-lactamase (BETA)–β-lactamase inhibitor (BLIP) has been used repeatedly as a test case for Phaser because the original structure solution by MR using AMoRe was difficult even though good models were available (the structures of both components had already been solved in isolation). The difficult part of the MR solution was placing BLIP. Phaser rapidly produces a correct solution for the complex.
This previously difficult structure solution becomes trivial because of two algorithms implemented in Phaser.
- The anisotropy correction; there is significant anisotropy in the data (the maximum B-factor difference in different directions is 32 Å²).
- The improved rotation-function target in MLRF, particularly in that the solution for BETA can be used to find the correct rotation-function solution for BLIP. Using the traditional Crowther (1972) fast rotation function, the Z score for the correct BLIP placement is 3.8 and the top Z score of 4.4 corresponds to an incorrect placement. Using MLRF and the prior knowledge about the placement of BETA, the correct placement of BLIP has a Z score of 6.5 and is the highest score in the search. (These results are for data that have had the anisotropy correction applied, to illustrate the improvement given by the MLRF alone.)
- Keyword script(s)
MODE MR_AUTO HKLIN beta_blip.mtz LABIN F=Fobs SIGF=Sigma ENSEMBLE BETA PDB beta.pdb ID 100 ENSEMBLE BLIP PDB blip.pdb ID 100 SEARCH ENSEMBLE BETA SEARCH ENSEMBLE BLIP
- Solving structures of protein complexes by molecular replacement with Phaser
- McCoy AJ
- Acta Cryst. (2007). D63, 32-41