title: Hydrogen/Deuterium Exchange Reflects Binding of Human Centrin 2 to Ca(2+) and Xeroderma Pigmentosum Group C Peptide: An Example of EX1 Kinetics.
abstract: Xeroderma pigmentosum (XP) is a genetic disease affecting 1 in 10,000-100,000 and predisposes people to early-age skin cancer, a disease that is increasing. Those with XP have decreased ability to repair UV-induced DNA damage, leading to increased susceptibility of cancerous non-melanomas and melanomas. A vital, heterotrimeric protein complex is linked to the nucleotide excision repair pathway for the damaged DNA. The complex consists of XPC protein, human centrin 2, and RAD23B. One of the members, human centrin 2, is a ubiquitous, acidic, Ca(2+)-binding protein belonging to the calmodulin superfamily. The XPC protein contains a sequence motif specific for binding to human centrin 2. We report here the Ca(2+)-binding properties of human centrin 2 and its interaction with the XPC peptide motif. We utilized a region-specific H/D exchange protocol to localize the interaction of the XPC peptide with the C-terminal domain of centrin, the binding of which is different than that of calmodulin complexes. The binding dynamics of human centrin 2 to the XPC peptide in the absence and presence of Ca(2+) are revealed by the observation of EX1 H/D exchange regime, indicating that a locally unfolded population exists in solution and undergoes fast H/D exchange.
authors: Analytical Research and Development, Pfizer Inc., Chesterfield, MO 63017 ; Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130.
authors: Justin B
authors: JB
authors: Sperry
authors: Zachary C
authors: ZC
authors: Ryan
authors: Rajiv
authors: R
authors: Kumar
authors: Michael L
authors: ML
authors: Gross
keywords: EX1 kinetics; centrin 2; hydrogen/deuterium exchange; protein; protein/peptide interaction; xeroderma pigmentosum