Department of Biochemistry, Biophysics and Molecular Biology - Iowa State University
Host: Dipali Sashital

"Real-time Observation of Target Search by the CRISPR Surveillance Complex Cascade"

CRISPR (clustered regularly interspaced short palindromic repeats) and the CRISPR-associated (Cas) genes are an RNA-guided adaptive immune system in prokaryotes. As an immune system, Cas proteins can acquire short fragments, named spacers, from the invader DNA or RNA and integrate these spacers into the host genomic CRISPR locus. Once transcribed and processed to short crRNA, these crRNA spacers can guide the Cas surveillance complexes (Cascade, Cas9, Cpf1, c2c2, c2c1, Csm, and Cmr) to their DNA and RNA target sequences, called protospacers, resulting in target cleavage. An existing protospacer (bona fide target or with mutations) can accelerate new spacers acquisition from the same invader’s DNA, a process called priming. 

We are interested in the mechanism of the type I-E CRISPR-Cas immune system in E. coli K12. Specifically, my research has focused on how interference and priming are related and how Cascade searches the target. 

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