Proteins and DNA elements essential for the CRISPR adaptation process in Escherichia coli

Ido Yosef, Moran G. Goren, Udi Qimron*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The clustered regularly interspaced short palindromic repeats and their associated proteins (CRISPR/Cas) constitute a recently identified prokaryotic defense mechanism against invading nucleic acids. Activity of the CRISPR/Cas system comprises of three steps: (i) insertion of alien DNA sequences into the CRISPR array to prevent future attacks, in a process called 'adaptation', (ii) expression of the relevant proteins, as well as expression and processing of the array, followed by (iii) RNA-mediated interference with the alien nucleic acid. Here we describe a robust assay in Escherichia coli to explore the hitherto least-studied process, adaptation. We identify essential genes and DNA elements in the leader sequence and in the array which are essential for the adaptation step. We also provide mechanistic insights on the insertion of the repeat-spacer unit by showing that the first repeat serves as the template for the newly inserted repeat. Taken together, our results elucidate fundamental steps in the adaptation process of the CRISPR/Cas system.

Original languageEnglish
Pages (from-to)5569-5576
Number of pages8
JournalNucleic Acids Research
Issue number12
StatePublished - Jul 2012


FundersFunder number
Seventh Framework Programme256340
United States-Israel Binational Science FoundationPIRG-GA-2009-256340, 2009218
Israel Science Foundation611/10


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