NMR elucidation of reduced B-Z transition activity of PKZ protein kinase at high NaCl concentration

Abstract

A Z-DNA binding protein (ZBP)-containing protein kinase (PKZ) in fish species has an important role in the innate immune response. Previous structural studies of the Zα domain of the PKZ from Carassius auratus (caZα_PKZ) showed that the protein initially binds to B-DNA and induces B-Z transition of double stranded DNA in a salt concentration-dependent manner. However, the significantly reduced B-Z transition activity of caZα_PKZ at high salt concentration was not fully understood. In this study, we present the binding affinity of the protein for B-DNA and Z-DNA and characterize its extremely low B-Z transition activity at 250 mM NaCl. Our results emphasize that the B-DNA-bound form of caZα_PKZ can be used as molecular ruler to measure the degree of B-Z transition.

Keywords: DNA-protein interaction; NMR; Salt effect; Z-DNA; Z-DNA binding protein.