A survey of ADP-ribosyltransferase families in the pathogenic Legionella.

BACKGROUND: ADP-ribosyltransferases (ARTs) are a superfamily of enzymes implicated in various cellular processes, including pathogenic mechanisms. The Legionella genus, known for causing Legionnaires’ disease, possesses diverse ART-like effectors. This study explores the proteomes of 41 Legionella species to bioinformatically identify and characterise novel ART-like families, providing insights into their potential roles in pathogenesis and host interactions. RESULTS: Our analysis identified 63 proteins with convincing similarity to ARTs, organised into 39 ART-like families, including 26 novel families. Key findings include: ● DUF2971 family: exhibits sequence similarity to DarT toxins and other DNA-acting ARTs. ● DUF4291 family: the largest newly identified family shows structural and sequence similarity to the diphtheria toxin, suggesting the ability to modify proteins. Most members of the novel ART families are predicted effectors. Although experimental validation of the predicted ART effector functions is necessary, the novel ART-like families identified present promising targets for understanding Legionella pathogenicity and developing therapeutic strategies. We published a complete catalogue of our results in the astARTe database: http://bioinfo.sggw.edu.pl/astarte/ . CONCLUSION: Detailed bioinformatic analyses of the proteomes of pathogenic bacteria reveal novel enzyme families likely involved in interactions with the host.