Abstract:Adenosine diphosphate-ribosylation (ADPr) is a reversible post-translational modification that is catalyzed by adenosine diphosphate-ribosyltransferases (ARTs) and adenosine diphosphate- ribosylhydrolases (ARHs), and it widely occurs in eukaryotes and prokaryotes. ARHs are a class of key enzymes that can reverse ADPr modification of specific amino acid residues or specific sites/sequences of DNA and RNA. They can regulate the physiological metabolism, signal transduction, gene expression, and other key life processes in bacteria or hosts, playing an important role in the inter/intraspecific competition, stress responses, and pathogenicity of bacteria. This article reviews the classification, structural characteristics, and catalytic mechanisms of bacterial ARHs, aiming to enrich our understanding about the catalytic mechanisms and biological functions of ARHs in bacterial life.