Crystallization and preliminary X-ray diffraction data of the complex between human centrin 2 and a peptide from the protein XPC

Centrins are highly conserved calcium-binding proteins involved in the nucleotide-excision repair pathway as a subunit of the heterotrimer including the XPC and hHR23B proteins. A complex formed by a Ca²⁺-bound human centrin 2 construct (the wild type lacking the first 25 amino acids) with a 17-mer peptide derived from the XPC sequence (residues Asn847–Arg863) was crystallized. Data were collected to 1.65 Å resolution from crystals grown in 30% monomethyl polyethylene glycol (MPEG) 500, 100 mM NaCl and 100 mM Bicine pH 9.0. Crystals are monoclinic and belong to space group C2, with two molecules in the asymmetric unit. The unit-cell parameters are a = 60.28, b = 59.42, c = 105.14 Å, α = γ = 90, β = 94.67°. A heavy-atom derivative was obtained by co-crystallization with Sr²⁺. The substitution was rationalized by calorimetry experiments, which indicate a binding constant for Sr²⁺ of 4.0 × 10⁴ M⁻¹.