EXPRESSION OF HUMAN POLY(ADP-RIBOSE) POLYMERASE IN SACCHAROMYCES-CEREVISIAE

The coding sequence for human poly(ADP-ribose) polymerase was expresse d inducibly in Saccharomyces cerevisiae from a low-copy-number plasmid vector. Cell free extracts of induced cells had poly(ADP-ribose) poly merase activity when assayed under standard conditions; activity could not be detected in noninduced cell extracts. Induced cells formed pol y(ADP-ribose) in vivo, and levels of these polymers increased when cel ls were treated with the alkylating agent N-methyl-N'-nitro-N-nitrosog uanidine (MNNG). The cytotoxicity of this agent was increased in induc ed cells, and in vivo labelling with [H-3] adenine further decreased t heir viability. Increased levels of poly(ADP-ribose) found in cells tr eated with the alkylating agent were not accompanied by lowering of th e NAD concentration.