Personne : Samson, Julie
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Samson
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Julie
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Département de biochimie, microbiologie et bio-informatique, Faculté des sciences et de génie, Université Laval
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ncf12004035
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Publication Accès libre Structure and activity of AbiQ, a lactococcal endoribonuclease belonging to the type III toxin–antitoxin system(Blackwell Scientific Publications, 2013-01-07) Moineau, Sylvain; Spinelli, Silvia; Samson, Julie; Cambillau, ChristianAbiQ is a phage resistance mechanism found on a native plasmid of Lactococcus lactis that abort virulent phage infections. In this study, we experimentally demonstrate that AbiQ belongs to the recently described type III toxin–antitoxin systems. When overexpressed, the AbiQ protein (ABIQ) is toxic and causes bacterial death in a bacteriostatic manner. Northern and Western blot experiments revealed that the abiQ gene is transcribed and translated constitutively, and its expression is not activated by a phage product. ABIQ is an endoribonuclease that specifically cleaves its cognate antitoxin RNA molecule in vivo. The crystal structure of ABIQ was solved and site-directed mutagenesis identified key amino acids for its anti-phage and/or its RNase function. The AbiQ system is the first lactococcal abortive infection system characterized to date at a structural level.Publication Restreint Bacteriophage resistance mechanisms(Nature Publishing Group, 2010-03-29) Moineau, Sylvain; Labrie, Simon; Samson, JuliePhages are now acknowledged as the most abundant microorganisms on the planet and are also possibly the most diversified. This diversity is mostly driven by their dynamic adaptation when facing selective pressure such as phage resistance mechanisms, which are widespread in bacterial hosts. When infecting bacterial cells, phages face a range of antiviral mechanisms, and they have evolved multiple tactics to avoid, circumvent or subvert these mechanisms in order to thrive in most environments. In this Review, we highlight the most important antiviral mechanisms of bacteria as well as the counter-attacks used by phages to evade these systems.Publication Restreint Bacteriophages in food fermentations : new frontiers in a continuous arms race(Annual Reviews, 2012-12-14) Moineau, Sylvain; Samson, JuliePhage contamination represents an important risk to any process requiring bacterial growth, particularly in the biotechnology and food industries. The presence of unwanted phages may lead to manufacturing delays, lower quality product, or, in the worst cases, total production loss. Thus, constant phage monitoring and stringent application of the appropriate control measures are indispensable. In fact, a systematic preventive approach to phage contamination [phage analysis and critical control points (PACCP)] should be put in place. In this review, sources of phage contamination and novel phage detection methods are described, with an emphasis on bacterial viruses that infect lactic acid bacteria used in food fermentations. Recent discoveries related to antiphage systems that are changing our views on phage-host interactions are highlighted. Finally, future directions are also discussed.Publication Restreint Bacteriophage resistance mechanisms(Nature Pub. Group, 2010-03-29) Moineau, Sylvain; Labrie, Simon; Samson, JuliePhages are now acknowledged as the most abundant microorganisms on the planet and are also possibly the most diversified. This diversity is mostly driven by their dynamic adaptation when facing selective pressure such as phage resistance mechanisms, which are widespread in bacterial hosts. When infecting bacterial cells, phages face a range of antiviral mechanisms, and they have evolved multiple tactics to avoid, circumvent or subvert these mechanisms in order to thrive in most environments. In this Review, we highlight the most important antiviral mechanisms of bacteria as well as the counter-attacks used by phages to evade these systems.