Chromosomal bacterial type II toxin–antitoxin systems

• Published in: Canadian journal of microbiology Vol. 58; no. 5; pp. 553 - 562
• Main Authors: Syed, Mohammad Adnan, Lévesque, Céline M
• Format: Journal Article
• Language: English
• Published: Ottawa, ON NRC Research Press 01.05.2012; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: addiction system; Antitoxins; Archaea - genetics; Archaea - metabolism; bacteria; Bacteria - genetics; Bacteria - metabolism; Bacterial genetics; Bacterial physiology; Bacterial proteins; Bacterial toxins; Bacterial Toxins - genetics; Bacterial Toxins - metabolism; Bacteriology; Biological and medical sciences; Cell growth; Chromosomes; Chromosomes, Bacterial - genetics; contrôle de la croissance; Endonucleases - genetics; Endonucleases - metabolism; environmental stress; Fundamental and applied biological sciences. Psychology; genes; Genetic aspects; growth control; microbial physiology; Microbiology; Miscellaneous; module toxine–antitoxine; persistance; persistence; Physiological aspects; Physiology; proteins; Ribonucleic acid; RNA; RNA Cleavage; RNA, Bacterial - genetics; RNA, Bacterial - metabolism; stress environnemental; système de dépendance; Toxins; toxin–antitoxin module; translation (genetics); Canada; Toxin; Bacteria; Toxin-antitoxin system; Stress
• ISSN: 1480-3275; 0008-4166; 1480-3275
• DOI: 10.1139/w2012-025

Most prokaryotic chromosomes contain a number of toxin–antitoxin (TA) modules consisting of a pair of genes that encode 2 components, a stable toxin and its cognate labile antitoxin. TA systems are also known as addiction modules, since the cells become “addicted” to the short-lived antitoxin product (the unstable antitoxin is degraded faster than the more stable toxin) because its de novo synthesis is essential for their survival. While toxins are always proteins, antitoxins are either RNAs (type I, type III) or proteins (type II). Type II TA systems are widely distributed throughout the chromosomes of almost all free-living bacteria and archaea. The vast majority of type II toxins are mRNA-specific endonucleases arresting cell growth through the mechanism of RNA cleavage, thus preventing the translation process. The physiological role of chromosomal type II TA systems still remains the subject of debate. This review describes the currently known type II toxins and their characteristics. The different hypotheses that have been proposed to explain their role in bacterial physiology are also discussed.