Functional characterization of the putative Aspergillus nidulans poly(ADP-ribose) polymerase homolog PrpA.

Poly(ADP-ribose) polymerase (PARP) is a highly conserved enzyme involved in multiple aspects of animal and plant cell physiology. For example, PARP is thought to be intimately involved in the early signaling events that trigger the DNA damage response. However, the genetic dissection of PARP function has been hindered by the presence of multiple homologs in most animal and plant species. Here, we present the first functional characterization of a putative PARP homolog (PrpA) in a microbial system (Aspergillus nidulans). PrpA belongs to a group of PARP homologs that includes representatives from filamentous fungi and protists. The genetic analysis of prpA demonstrates that it is an essential gene whose role in the DNA damage response is sensitive to gene dosage. Notably, temporal patterns of prpA expression and PrpA-GFP nuclear localization suggest that PrpA acts early in the A. nidulans DNA damage response. Additional studies implicate PrpA in farnesol-induced cell death and in the initiation of asexual development. Collectively, our results provide a gateway for probing the diverse functions of PARP in a sophisticated microbial genetic system.