Anna Grabowska, Michele Cianci, André Colom, Thomas R. Schneider, Dirk Schnappinger, Annabel H. A. Parret, Terezie Panikova, Luiz Pedro S. de Carvalho, Vivian Pogenberg, Claude Gutierrez, Olivier Neyrolles, Katherine S. H. Beckham, Kanchiyaphat Ariyachaokun, Pierre Genevaux, Laure Botella, Yves-Marie Boudehen, Acely Garza-Garcia, Anne Tuukkanen, Dmitri I. Svergun, Diana Freire, Matthias Wilmanns, Ambre Sala, Antonio Peixoto, PRO-MED sp. z o.o., PRO-MED, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre de Biochimie Structurale [Montpellier] (CBS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Santé et de la Recherche Médicale (INSERM), European Molecular Biology Laboratory [Hamburg] (EMBL), Laboratoire de microbiologie et génétique moléculaires (LMGM), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), European Molecular Biology Laboratory, Institut de pharmacologie et de biologie structurale (IPBS), Centre de Biologie Intégrative (CBI), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées
Summary Toxin-antitoxin (TA) systems regulate fundamental cellular processes in bacteria and represent potential therapeutic targets. We report a new RES-Xre TA system in multiple human pathogens, including Mycobacterium tuberculosis. The toxin, MbcT, is bactericidal unless neutralized by its antitoxin MbcA. To investigate the mechanism, we solved the 1.8 Å-resolution crystal structure of the MbcTA complex. We found that MbcT resembles secreted NAD+-dependent bacterial exotoxins, such as diphtheria toxin. Indeed, MbcT catalyzes NAD+ degradation in vitro and in vivo. Unexpectedly, the reaction is stimulated by inorganic phosphate, and our data reveal that MbcT is a NAD+ phosphorylase. In the absence of MbcA, MbcT triggers rapid M. tuberculosis cell death, which reduces mycobacterial survival in macrophages and prolongs the survival of infected mice. Our study expands the molecular activities employed by bacterial TA modules and uncovers a new class of enzymes that could be exploited to treat tuberculosis and other infectious diseases., Graphical Abstract, Highlights • MbcTA is a RES-Xre toxin-antitoxin system in M. tuberculosis (Mtb) • MbcT is a NAD+ phosphorylase • MbcT-catalyzed NAD+ depletion leads to Mtb cell death • MbcT activity synergizes with antibiotics to reduce Mtb burden in infected mice, Toxin-antitoxin systems regulate bacterial growth in response to stress through modification of macromolecules, including proteins, RNA, and DNA. Freire et al. show that MbcT, a toxin produced by the tubercle bacillus, induces bacterial cell death through NAD+ phosphorolysis, an unprecedented enzymatic activity.