H-NS mediated repression of CRISPR-based immunity in Escherichia coli K12 can be relieved by the transcription activator LeuO

Edze Rients Westra (1) , Ümit Pul (2) , Nadja Heidrich (3) , Matthijs Miklas Jore (4) , Magnus Lundgren (3) , Thomas Stratmann (5) , Reinhild Wurm (2) , Amanda Raine (6) , Melina Mescher (2) , Luc Van Heereveld (4) , Marieke Mastop (4) , E. Gerhart H. Wagner (6) , Karin Schnetz (7) , John van Der Oost (4) , Rolf Wagner (2) , Stan J.J. Brouns (4)

1 Microbiology
2 Institute of Molecular Evolution
3 Institute of Cell and Molecular Biology
4 Laboratory of Microbiology
5 Institute for Genetics
6 Department of Cell and Molecular Biology [Uppsala]
7 Institute for Genetics

The recently discovered prokaryotic CRISPR/Cas defense system provides immunity against viral infections and plasmid conjugation. It has been demonstrated that in Escherichia coli transcription of the Cascade genes (casABCDE) and to some extent the CRISPR array, is repressed by heat-stable nucleoid-structuring (H-NS) protein, a global transcriptional repressor. Here we elaborate on the control of the E. coli CRISPR/Cas system, and study the effect on CRISPR-based anti-viral immunity. Transformation of wild-type E. coli K12 with CRISPR spacers that are complementary to phage Lambda, does not lead to detectable protection against Lambda infection. However, when an H-NS mutant of E. coli K12 is transformed with the same anti-Lambda CRISPR, this does result in reduced sensitivity to phage infection. In addition, it is demonstrated that LeuO, a LysR-type transcription factor, binds to two sites flanking the casA promoter and the H-NS nucleation site, resulting in derepression of casABCDE12 transcription. Over-expression of LeuO in E. coli K12 containing an anti-Lambda CRISPR leads to an enhanced protection against phage infection. This study demonstrates that in E. coli H-NS and LeuO are antagonistic regulators of CRISPR-based immunity.

Mots clés: Life Sciences

Edze Rients Westra, Ümit Pul, Nadja Heidrich, Matthijs Miklas Jore, Magnus Lundgren, et al.. H-NS mediated repression of CRISPR-based immunity in Escherichia coli K12 can be relieved by the transcription activator LeuO. Molecular Microbiology, 2010, 77 (6), pp.1380. ⟨10.1111/j.1365-2958.2010.07315.x⟩. ⟨hal-00560024⟩