Not all empty MHC class I molecules are molten globules: tryptophan fluorescence reveals a two-step mechanism of thermal denaturation.

When major histocompatibility complex (MHC) class I molecules bind peptide, they change their conformation and their dynamics. The structure and properties of the peptide-empty class I are still largely unknown. We have investigated the thermal denaturation of the murine class I allotypes H-2D(b) and H-2K(b) through the fluorescence of their intrinsic tryptophans, and we find that it occurs via an empty form that can also be produced by folding denatured recombinant class I molecules.

Human papillomavirus 16 E7 oncoprotein attenuates DNA damage checkpoint control by increasing the proteolytic turnover of claspin.

The human papillomavirus (HPV) 16 E7 oncoprotein has been reported previously to stimulate DNA damage and to activate host cell DNA damage checkpoints. How HPV-16 E7 maintains proliferation despite activated DNA damage checkpoints is incompletely understood. Here, we provide evidence that cells expressing the HPV-16 E7 oncoprotein can enter mitosis in the presence of DNA damage.