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Toxins 2018, 10(9), 378;

The Streptococcus pneumoniae yefM-yoeB and relBE Toxin-Antitoxin Operons Participate in Oxidative Stress and Biofilm Formation

i-DNA Biotechnology (M) Sdn Bhd. A-1-6 Pusat Perdagangan Kuchai, No. 2, Jalan 1/127, Kuchai Entrepreneurs Park, Kuala Lumpur 58200, Malaysia
Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain
CIBER de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, 28040 Madrid, Spain
Authors to whom correspondence should be addressed.
Present addresses: Department of Parasitology, GlaxoSmithKline, Severo Ochoa, 2, 28760-Tres Cantos, 28760 Madrid, Spain.
Present addresses: Department of Microbiology, University Hospital A Coruña (CHUAC)—Biomedical Research Institute A Coruña (INIBIC), Xubias de Arriba, 84, 15006 A Coruña, Spain.
Received: 9 August 2018 / Revised: 3 September 2018 / Accepted: 13 September 2018 / Published: 18 September 2018
(This article belongs to the Special Issue Toxin-antitoxin (TA) systems)
PDF [2001 KB, uploaded 18 September 2018]


Type II (proteic) toxin-antitoxin systems (TAs) are widely distributed among bacteria and archaea. They are generally organized as operons integrated by two genes, the first encoding the antitoxin that binds to its cognate toxin to generate a harmless protein–protein complex. Under stress conditions, the unstable antitoxin is degraded by host proteases, releasing the toxin to achieve its toxic effect. In the Gram-positive pathogen Streptococcus pneumoniae we have characterized four TAs: pezAT, relBE, yefM-yoeB, and phD-doc, although the latter is missing in strain R6. We have assessed the role of the two yefM-yoeB and relBE systems encoded by S. pneumoniae R6 by construction of isogenic strains lacking one or two of the operons, and by complementation assays. We have analyzed the phenotypes of the wild type and mutants in terms of cell growth, response to environmental stress, and ability to generate biofilms. Compared to the wild-type, the mutants exhibited lower resistance to oxidative stress. Further, strains deleted in yefM-yoeB and the double mutant lacking yefM-yoeB and relBE exhibited a significant reduction in their ability for biofilm formation. Complementation assays showed that defective phenotypes were restored to wild type levels. We conclude that these two loci may play a relevant role in these aspects of the S. pneumoniae lifestyle and contribute to the bacterial colonization of new niches. View Full-Text
Keywords: Streptococcus pneumonia; toxin–antitoxin; relBE; yefM-yoeB; oxidative stress; biofilm formation Streptococcus pneumonia; toxin–antitoxin; relBE; yefM-yoeB; oxidative stress; biofilm formation

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Chan, W.T.; Domenech, M.; Moreno-Córdoba, I.; Navarro-Martínez, V.; Nieto, C.; Moscoso, M.; García, E.; Espinosa, M. The Streptococcus pneumoniae yefM-yoeB and relBE Toxin-Antitoxin Operons Participate in Oxidative Stress and Biofilm Formation. Toxins 2018, 10, 378.

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