Functional effects of CRP binding to nuclei.

Binding of human CRP and rat CRP to their respective autologous liver nuclei has been demonstrated. The binding was shown to consist of both a calcium- and non-calcium-dependent component. The co-precipitation of human CRP with histones in physiological calcium concentrations suggests that the calcium-independent binding to chromatin is mediated by the CRP-polycation site. Complement-dependent chromatin solubilization by human CRP bound to nuclei was confirmed and show that the solubilized material is intact chromatin with a large proportion of small monosome structures of 180 base pair repeat. The binding of human and rat CRP to nuclei enhanced micrococcal nuclease digestion, suggesting that CRP binding in both these species alters chromatin structure by increasing linker DNA exposure. The suppressed transcription of DNA, after saturating CRP binding to nuclei, could limit aberrant transcription of damaged chromatin.