CRISPR–Cas systems are adaptive immune systems in prokaryotes that provide protection against viruses and other foreign DNA. In the adaptation stage, foreign DNA is integrated into CRISPR (clustered regularly interspaced short palindromic repeat) arrays as new spacers. These spacers are used in the interference stage to guide effector CRISPR associated (Cas) protein(s) to target complementary foreign invading DNA. Cas1 is the integrase enzyme that is central to the catalysis of spacer integration. There are many diverse types of CRISPR–Cas systems, including type I-F systems, which are typified by a unique Cas1–Cas2–3 adaptation complex. In the present study we characterize the Cas1 protein of the potato phytopathogen Pectobacterium atrosepticum, an important model organism for understanding spacer acquisition in type I-F CRISPR–Cas systems. We demonstrate by mutagenesis that Cas1 is essential for adaptation in vivo and requires a conserved aspartic acid residue. By X-ray crystallography, we show that although P. atrosepticum Cas1 adopts a fold conserved among other Cas1 proteins, it possesses remarkable asymmetry as a result of structural plasticity. In particular, we resolve for the first time a flexible, asymmetric loop that may be unique to type I-F Cas1 proteins, and we discuss the implications of these structural features for DNA binding and enzymatic activity.
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April 2016
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Collagen helical symmetry varies with its amino acid sequence: shown is a helix with seventeen-fold symmetry, this is a good representation for the average conformation of the entire collagen molecule. For further details see pp. 1001-1025. Image kindly provided by Dr Jordi Bella. - PDF Icon PDF LinkFront Matter
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Research Article|
April 08 2016
Structural plasticity and in vivo activity of Cas1 from the type I-F CRISPR–Cas system
Max E. Wilkinson;
Max E. Wilkinson
2
*Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
†Department of Biochemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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Yoshio Nakatani;
Yoshio Nakatani
*Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
†Department of Biochemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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Raymond H.J. Staals;
Raymond H.J. Staals
*Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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Sebastian N. Kieper;
Sebastian N. Kieper
3
*Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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Helen K. Opel-Reading;
Helen K. Opel-Reading
†Department of Biochemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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Rebecca E. McKenzie;
Rebecca E. McKenzie
3
*Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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Peter C. Fineran;
Peter C. Fineran
1
*Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
1Correspondence may be addressed to either of these authors (email: peter.fineran@otago.ac.nz or kurt.krause@otago.ac.nz).
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Kurt L. Krause
Kurt L. Krause
1
†Department of Biochemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand
1Correspondence may be addressed to either of these authors (email: peter.fineran@otago.ac.nz or kurt.krause@otago.ac.nz).
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Publisher: Portland Press Ltd
Received:
December 18 2015
Revision Received:
February 15 2016
Accepted:
February 16 2016
Accepted Manuscript online:
February 29 2016
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society
2016
Biochem J (2016) 473 (8): 1063–1072.
Article history
Received:
December 18 2015
Revision Received:
February 15 2016
Accepted:
February 16 2016
Accepted Manuscript online:
February 29 2016
Citation
Max E. Wilkinson, Yoshio Nakatani, Raymond H.J. Staals, Sebastian N. Kieper, Helen K. Opel-Reading, Rebecca E. McKenzie, Peter C. Fineran, Kurt L. Krause; Structural plasticity and in vivo activity of Cas1 from the type I-F CRISPR–Cas system. Biochem J 15 April 2016; 473 (8): 1063–1072. doi: https://doi.org/10.1042/BCJ20160078
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