Dephosphorylation of histone H1 after mengovirus infection of Ehrlich ascites tumor cells.

The effect of mengovirus infection on the extent of phosphorylation of histone H1 was studied in Ehrlich ascites tumor cells. After prelabeling of the nuclear protein with [32P] orthophosphate, the excorporation of radioactivity was followed as a function of time postinfection. Employing high-resolution polyacrylamide gradient slab gel electrophoresis and autoradiography, it was found that, compared to a relatively slow turnover of phosphate groups in histone H1 in mock-infected cells, in mengovirus-infected cells the excorporation of radiolabel from histone H1 was significantly enhanced. In the latter case, the decrease of histone-bound radioactivity was paralleled by a reduction of the band multiplicity in the histone H1 region of the electrophoresis profile. It was also shown that the microheterogeneity in the histone H1 complements isolated at various times postinfection was reduced to the same basal 3-band level by incubation of the nuclear protein fractions in the presence of alkaline phosphatase. After this treatment, the band multiplicity equaled that found in histone H1 from stationary cells.