Personne : Ouellette, Marc
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Ouellette
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Marc
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Université Laval. Département de microbiologie-infectiologie et d'immunologie
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0000000071261727
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ncf13672217
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Publication Accès libre Complete genome sequence of streptococcus pneumoniae virulent phage MS1(American Society for Microbiology, 2017-07-13) Kot, Witold; Tremblay, Denise; Gingras, Hélène; Moineau, Sylvain; Sabri, Mourad; Ouellette, MarcThe lytic Streptococcus pneumoniae phage MS1 was isolated from a throat swab of a patient with symptoms of upper respiratory tract infection. The genome of this siphophage has 56,075 bp, 42.3% GC content, and 77 open reading frames, including queuosine biosynthesis genes. Phage MS1 is related to pneumococcal phage Dp-1.Publication Accès libre Involvement of Dcr1 in post-transcriptional regulation of gene expression in Schizosaccharomyces pombe.(Frontiers In Bioscience Publications, 2008-01-01) Plante, Pierre; Provost, Patrick; Rohani, Mina; Gobeil, Lise-Andrée; Ouellette, MarcThe ribonuclease III Dicer (Dcr1) has been shown to be required for chromosome segregation and gene silencing in Schizosaccharomyces pombe. These effects are thought to be transcriptional, mediated by formation and maintenance of heterochromatin, and guided by small RNAs derived from Dcr1 along a process known as RNA interference. In order to get further insights into the gene regulatory role of Dcr1, we performed comparative analyses of dcr1 knockout and wild-type fission yeast strains. Analysis of part of the soluble proteomes identified eight cellular proteins whose expression is under Dcr1 control, three of which are integral constituents of the glycolysis pathway. Further correlations with their respective mRNA transcript levels are compatible with the existence of a post-transcriptional gene regulatory mechanism involving Dcr1 or a Dcr1 complex. Experiments designed to identify components of Dcr1 complexes unveiled two novel Dcr1 interactors, namely the zinc finger protein Byr3 and the ribosomal protein L12. Consistently enriched in Dcr1 immune complexes, Byr3 and L12 may link Dcr1 to the transcriptional and translational machineries, respectively, and contribute to post-transcriptional gene regulation in fission yeast.Publication Accès libre A genomic approach to understand interactions between Streptococcus pneumoniae and its bacteriophages(BioMed Central, 2015-11-18) Gingras, Hélène; Ouennane, Siham; Moineau, Sylvain; Ouellette, Marc; Leprohon, PhilippeBackground: Bacteriophage replication depends on bacterial proteins and inactivation of genes coding for such host factors should interfere with phage infection. To gain further insights into the interactions between S. pneumoniae and its pneumophages, we characterized S. pneumoniae mutants selected for resistance to the virulent phages SOCP or Dp-1. Results: S. pneumoniae R6-SOCPR and R6-DP1R were highly resistant to the phage used for their selection and no cross-resistance between the two phages was detected. Adsorption of SOCP to R6-SOCPR was partly reduced whereas no difference in Dp-1 adsorption was noted on R6-DP1R. The replication of SOCP was completely inhibited in R6-SOCPR while Dp-1 was severely impaired in R6-DP1R. Genome sequencing identified 8 and 2 genes mutated in R6-SOCPR and R6-DP1R , respectively. Resistance reconstruction in phage-sensitive S. pneumoniae confirmed that mutations in a GntR-type regulator, in a glycerophosphoryl phosphodiesterase and in a Mur ligase were responsible for resistance to SOCP. The three mutations were additive to increase resistance to SOCP. In contrast, resistance to Dp-1 in R6-DP1R resulted from mutations in a unique gene coding for a type IV restriction endonuclease. Conclusion: The characterization of mutations conferring resistance to pneumophages highlighted that diverse host genes are involved in the replication of phages from different families.Publication Restreint Genome annotation and intraviral interactome for the Streptococcus pneumoniae virulent phage Dp-1(American Society for Microbiology, 2010-12-28) Moineau, Sylvain; Häuser, Roman; Sabri, Mourad; Ouellette, Marc; Liu, Jing; Dehbi, Mohammed; Moeck, Greg; García López, Ernesto Ángel; Titz, Björn; Uetz, PeterStreptococcus pneumoniae causes several diseases, including pneumonia, septicemia, and meningitis. Phage Dp-1 is one of the very few isolated virulent S. pneumoniae bacteriophages, but only a partial characterization is currently available. Here, we confirmed that Dp-1 belongs to the family Siphoviridae. Then, we determined its complete genomic sequence of 56,506 bp. It encodes 72 open reading frames, of which 44 have been assigned a function. We have identified putative promoters, Rho-independent terminators, and several genomic clusters. We provide evidence that Dp-1 may be using a novel DNA replication system as well as redirecting host protein synthesis through queuosine-containing tRNAs. Liquid chromatography-mass spectrometry analysis of purified phage Dp-1 particles identified at least eight structural proteins. Finally, using comprehensive yeast two-hybrid screens, we identified 156 phage protein interactions, and this intraviral interactome was used to propose a structural model of Dp-1.