OCT 03, 2019 9:00 AM PDT

Structures of CRISPR-Cas surveillance complexes

Presented at: CRISPR 2019
C.E. Credits: P.A.C.E. CE Florida CE
  • Assistant Professor and CPRIT Scholar, Department of Molecular Biosciences, University of Texas at Austin
      David Taylor started as an Assistant Professor in the Department of Molecular Biosciences at the University of Texas at Austin in 2016. There, he is the Director of the Sauer Structural Biology Laboratory and a member the Center for Systems and Synthetic Biology and the LIVESTRONG Cancer Institutes at Dell Medical School. His laboratory is focused on structural and mechanistic studies of CRISPR-Cas surveillance complexes and methods development for cryo-electron microscopy (cryo-EM). David received his B.S. in Biochemistry summa cum laude from Syracuse University in 2008. He completed his Ph.D. with distinction in Molecular Biophysics and Biochemistry at Yale University in 2013. In 2014, he joined the laboratories of Jennifer A. Doudna and Eva Nogales at the University of California, Berkeley as a Post-doctoral Fellow, where he studied the structures of CRISPR complexes using cryo-electron microscopy. He has won numerous awards during his short career. He's been named a Barry M. Goldwater Scholar, an NSF Pre-doctoral Fellow, an NSF East Asia and Pacific Summer Institute Fellow, a Damon Runyon Fellow, a CPRIT Scholar, and an Army Young Investigator. He's received the Outstanding Teaching Award and the Mary Ellen Jones Dissertation Prize from the Department of Molecular Biophysics and Biochemistry at Yale University. He also received the 2015 Outstanding Post-doctoral Fellow Award from the Department of Molecular and Cell Biology at the University of California, Berkeley.


    CRISPR (clustered regularly interspaced short palindromic repeats) RNA and CRISPR-associated genes (Cas) assemble into RNA-guided surveillance complex that targets foreign nucleic acids for destruction. There are two major classes of CRISPR-Cas systems. Class I systems utilize a multi-subunit effector complex called Cascade to recognize and degrade target nucleic acids; whereas, Class II systems employ a single polypeptide for these activities. Here, I present structures of a novel, uncharacterized Type IV surveillance complex from Class I. It has striking similarity to Type III Cmr effector complexes. It is tempting to hypothesize that it targets single-stranded RNA. I also present detailed kinetic characterization of high-fidelity Class II Cas9 variants. These high-fidelity enzymes achieve specificity by altering the kinetic portioning and allowing substrate release prior to the irreversible cleavage reaction.

    Learning outcomes:

    1. Understand how cryo-EM can be used for structural studies of CRISPR-Cas complexes.  
    2. Interpret kinetic data of Cas9 complexes.

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