Crystallization and preliminary X-ray crystallographic studies of the [NiFe] hydrogenase maturation proteins HypC and HypD

HypC and HypD proteins are required for the insertion of the Fe atom with diatomic ligands into the large subunit of [NiFe] hydrogenases, an important step in the maturation process of this type of hydrogenase. The crystallization and preliminary crystallographic analysis of HypC and HypD from Thermococcus kodakaraensis KOD1 are reported. Crystals of HypC grew in two different forms. Monoclinic crystals of HypC in space group C2 with unit-cell parameters a = 78.2, b = 59.1, c = 54.0 Å, β = 109.0° were obtained using PEG 4000 and ammonium sulfate or sodium bromide as precipitants. They diffracted X-rays to 1.8 Å resolution and were suitable for structure determination. Crystals of HypD were also obtained in two different forms. The monoclinic crystals obtained using PEG 4000 and magnesium chloride diffracted X-rays to beyond 2.1 Å resolution, despite growing as clusters. They belong to space group P2₁, with unit-cell parameters a = 42.3, b = 118.4, c = 81.2 Å, β = 100.9°, and are suitable for data collection.