Expression of foot and mouth disease virus non-structural polypeptide 3ABC induces histone H3 cleavage in BHK21 cells

Auto-processing of the non-structural polypeptide 3ABC of foot and mouth disease virus (FMDV) expressed in Escherichia coli-BL21-DE3 was prevented by mutating either four glutamic acid residues at the 3A/3B1, 3B1/2, 3B2/3 and 3B3/3C junctions (3ABCtet) or a single cysteine residue at position 383 within the 3C domain (3ABCm). Independent expression of 3ABC and 3ABCtet genes induced expression of chaperone DnaK and degradation of ribosomal S1 protein in E. coli. They also induced cleavage of nucleosomal histone H3 when transiently expressed in BHK21 cells. 3ABCtet, 3ABCm, 3AB and 3A proteins concentrated in the perinuclear region suggesting that peptide sequences within the 3A domain specify intracellular targeting of 3ABC in BHK-21 cells. We propose that 3ABC molecules localized in the nuclear periphery are a source of protease 3C activity and are responsible for histone H3 processing during FMDV infections.