The gateway to X-ray crystallography is the growth of macromolecular crystals. An attempt is made here to acquaint investigators with the principles and practice of protein crystallization, some recent innovations, and to touch upon some of the remaining problems.
Structural and biochemical data demonstrate that p202 recognizes foreign DNA in a distinct manner compared with AIM2/Aim2, leading to a new model for the negative regulation of Aim2-mediated inflammasome activation by p202.
An oligopeptide containing a reduced analogue of a Phe-Tyr dipeptide was found to have good inhibition activity against endothiapepsin, and the crystal structure of the inhibitor–enzyme complex has been determined at 1.35 Å resolution.
The crystal structure of the R80N mutant of nucleoside diphosphate kinase from M. tuberculosis has been determined at 1.9 Å resolution. Biochemical data and structural analysis provide important information on the stability of the hexamer. A citrate is bound in the catalytic site where the nucleotide phosphate groups are usually located.
The DNA-binding domains of Ets1 and FOXO1 were expressed, purified, and crystallized in complex with DNA containing a composite sequence for a noncanonical forkhead binding site and an ETS site. Diffraction data were collected to a resolution of 2.2 Å.
The N-terminal calmodulin-like domain of the human mitochondrial ATP-Mg/Pi carrier SCaMC1 was crystallized in the presence of Ca2+. X-ray diffraction data were collected to 2.9 Å resolution from crystals which belonged to space group P6222.
A double mutation (P453H and I471T) improved the solubility of the middle domain of PB2 from influenza A virus and the shape of the crystals that were obtained. A small crystal was used to test the diffraction and a preliminary X-ray diffraction data set was collected to 2.30 Å resolution.
Crystals of the small subunit of POXA3b, a heterodimeric laccase (multicopper oxidase) from P. ostreatus, belonged to space group P41212 or P43212 and contained two molecules in the asymmetric unit related by a noncrystallographic twofold axis. X-ray data were collected to a maximum resolution of 2.5 Å using a synchrotron source.
A feast/famine regulatory protein (Rv2779c) from M. tuberculosis H37Rv was cloned, overexpressed, purified and crystallized. The crystals diffracted to a resolution of 2.8 Å and belonged to space group P21212.
Recombinant human fumarase has been overexpressed in E. coli and crystallized in the presence of polyethylene glycol as a precipitant agent. The structure was solved by molecular-replacement techniques.
Despite possessing an N-terminal F-BAR domain, the srGAP2 protein regulates neurite outgrowth and neuronal migration by causing membrane protrusions reminiscent of the activity of I-BAR domain proteins. In this study, the F-BAR domain of human srGAP2 was crystallized and diffracted to 3.50 Å resolution.
The intrinsic variability between and within macromolecular crystals has a large effect on screening and data-collection strategies. Measures of this variability and their implications for data collection are presented.