A B S T R A C T ADP-ribosylation (ADPr) is an ancient reversible modification of cellular macromolecules controlling major biological processes as diverse as DNA damage repair, transcriptional regulation, intracellular transport, immune and stress responses, cell survival and proliferation. Furthermore, enzymatic reactions of ADPr are central in the pathogenesis of many human diseases, including infectious conditions. By providing a review of ADPr signalling in bacterial systems, we highlight the relevance of this chemical modification in the pathogenesis of human diseases depending on host-pathogen interactions. The post-antibiotic era has raised the need to find alternative approaches to antibiotic administration, as major pathogens becoming resistant to antibiotics. An in-depth understanding of ADPr reactions provides the rationale for designing novel antimicrobial strategies for treatment of infectious diseases. In addition, the understanding of mechanisms of ADPr by bacterial virulence factors offers important hints to improve our knowledge on cellular processes regulated by eukaryotic homologous enzymes, which are often involved in the pathogenesis of human diseases.T large number of worldwide spread diseases, affecting humans, insects and plants [31,[56][57][58], with a great impact on human health. In addition, infectious diseases strongly affect the world economy in terms of costs for the human health as well as food and agricultural economic losses [59]. The use of antibiotics to counteract the pathogen infections has represented the therapeutic strategy of choice in the last century, however the emergence of antibiotic resistance strains represents the major challenge of the 21st century [60][61][62]. Targeting bacterial pathogenic mechanisms by disarming pathogens of virulence factors, for instance by inhibiting the enzymatic activity of bART, represents a valid alternative intervention strategy to overcome antibiotic resistance [63][64][65][66]. In addition, because of the conservation of ADPr systems throughout the evolution, the understanding of bacterial pathogenic mechanisms may contribute to unveil novel and conserved cellular processes regulated by ADPr in high organisms [34,45,67,68]. The dysregulation of such processes can be either cause of human diseases or be target of therapeutic intervention [39,[69][70][71].Herein, we will provide a summary of bacterial ADPr systems describing their pathogenic mechanisms and highlighting the similarities with ADPr systems in mammals as well. Further, we discuss the potential of targeting ADPr for therapeutic strategies of infection diseases.
ADP-ribosylation in pathophysiologyADPr was originally described in the 60s; two independent studies reported the identification of a new polymer, poly(ADP-ribose) (PAR) synthesised from NAD + in vertebrate cells [72] and, simultaneously, the finding that bacterial DTX activity from C. diphteriae is dependent on NAD + content [73]. In the following decades, research in the field has expanded the involvement of ADPr ...