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Immunity of bacteria against foreign nucleic acids

A biochemical approach
To protect themselves against phages (viruses) and other invading genetic elements (plasmids), microorganisms (bacteria and archaea) have acquired strategies based on degradation of nucleic acids from the infectious agents.

Among these systems, a recently discovered one confers immunity to microorganisms against DNA of foreign origin. Once acquired, this immunity is transmitted to the progeny for numerous generations. It lies on the capture and insertion of foreign genetic elements .at dedicated loci in the chromosome.

These loci are called Clustered Regularly Interspaced Short Palindromic Repeats or CRISPR. They are functionally linked to proteins encoded by cas (CRISPR-associated) genes, usually arranged in operons and located in close vicinity of CRISPR loci. CRISPR loci are transcribed from a promoter site and transcripts are processed into small RNAs. These RNAs direct irreversible degradation by nucleases of the DNA of remembered invaders.

Our current research deals with the mechanisms of integration of novel DNA inserts inside a CRISPR locus. In particular, we focus biochemical and biophysical approaches on the properties of the Cas proteins involved in the process. This research project was launched on the occasion of the establishment in the lab of a chair of excellence Ecole polytechnique-CNRS.


Publication
Norais, C, Moisan, A, Gaspin, C, Clouet-d'Orval, B. Diversity of CRISPR systems in the euryarchaeal Pyrococcales. RNA Biol. 10, in press (2013) [Abstract]

People
Cedric Norais, Lecturer, holder of the chair of excellence Polytechnique-CNRS
Sylvain Blanquet, Emeritus Senior Researcher at CNRS and Emeritus Professor at Ecole polytechnique
Michel Fromant, Engineer at Ecole polytechnique
Clara Moch, Engineer at CNRS
Pierre Plateau, CNRS Senior Research Scientist

Former group member
Caroline Launay, Engineer at CNRS
Graduate internships
Alexander Rehn, University of Aachen, Germany
Claire Duvallet, Columbia University, USA