Linker histones do not interact with DNA containing a single interstrand cross-link created by cisplatin

During our earlier investigations we have observed a prominent preference of the linker histone H1 for binding to a cis-platinated DNA (a synthetic fragment with global type of platination in respect to targets for cisplatin) comparing with unmodified and trans-Pt-modified DNA. In the present work we report our recent experimental results on the binding of the linker histones H1 and H5 to a cisplatin-modified synthetic DNA fragment containing a single nucleotide target d(GC/CG) for inter-platination. Surprisingly, no preferential binding of linker histones to cis-inter-platinated DNA was observed by means of the electromobility-shift assay. The same negative results were obtained with a part of the linker histone molecule suggested to be responsible for DNA-binding--its globular domain. Contrary, the data with another nuclear protein with similar DNA-binding properties as linker histones--HMGB1--showed a strong afinity for interaction with DNA containing interstrand cross-links.