Crystallization of the pneumococcal autolysin LytC: in-house phasing using novel lanthanide complexes

LytC, one of the major autolysins from the human pathogen Streptococcus pneumoniae, has been crystallized as needles by the hanging-drop technique using 10%(w/v) PEG 3350 as precipitant and 10 mM HEPES pH 7.5. LytC crystals were quickly soaked in mother liquor containing 2 mM of the complex Gd-HPDO3A to produce derivatized crystals (LytC_Gd-HPDO3A). Both native LytC and isomorphous LytC_Gd-HPDO3A crystals were flash-cooled in a nitrogen flow at 120 K prior to X-ray data collection using an in-house Enraf–Nonius rotating-anode generator (λ = 1.5418 Å) and a MAR345 imaging-plate detector. In both cases, good-quality diffraction patterns were obtained at high resolution. LytC_Gd-HPDO3A crystals allowed the collection of a SAD X-ray data set to 2.6 Å resolution indexed in terms of a P2₁ monoclinic unit cell with parameters a = 59.37, b = 67.16, c = 78.85 Å, β = 105.69°. The anomalous Patterson map allowed the identification of one heavy-atom binding site, which was sufficient for the calculation of an interpretable anomalous map at 2.6 Å resolution.