Casposase structure and the mechanistic link between DNA transposition and spacer acquisition by CRISPR-Cas

Abstract
Data availability
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Abstract

Key to CRISPR-Cas adaptive immunity is maintaining an ongoing record of invading nucleic acids, a process carried out by the Cas1-Cas2 complex that integrates short segments of foreign genetic material (spacers) into the CRISPR locus. It is hypothesized that Cas1 evolved from casposases, a novel class of transposases. We show here that the Methanosarcina mazei casposase can integrate varied forms of the casposon end in vitro, and recapitulates several properties of CRISPR-Cas integrases including site-specificity. The X-ray structure of the casposase bound to DNA representing the product of integration reveals a tetramer with target DNA bound snugly between two dimers in which single-stranded casposon end binding resembles that of spacer 3'-overhangs. The differences between transposase and CRISPR-Cas integrase are largely architectural, and it appears that evolutionary change involved changes in protein-protein interactions to favor Cas2 binding over tetramerization; this in turn led to preferred integration of single spacers over two transposon ends.

Data availability

Diffraction data for the casposase-DNA complex have been deposited under PBD ID 6OPM. The GSE number for the NGS data is GSE139037.

The following data sets were generated

1. Hickman AB
2. Kailasan S
3. Genzor P
4. Haase AD
5. Dyda F
(2019) Casposase structure and the mechanistic link between DNA transposition and spacer acquisition by CRISPR-Cas
NCBI Gene Expression Omnibus, GSE139037.

https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE139037
1. Hickman AB
2. Kailasan S
3. Genzor P
4. Haase AD
5. Dyda F
(2019) NGS data
Protein Data Bank, 6OPM.

https://www.rcsb.org/structure/6OPM

Article and author information

Author details

Alison B Hickman

Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-7666-0249
Shweta Kailasan

Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-0876-6812
Pavol Genzor

Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States

Competing interests
The authors declare that no competing interests exist.
Astrid D Haase

Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States

Competing interests
The authors declare that no competing interests exist.
Fred Dyda

Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States

For correspondence
Fred.Dyda@nih.gov

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-1689-9041

Funding

National Institute of Diabetes and Digestive and Kidney Diseases (Intramural Program)

Alison B Hickman
Shweta Kailasan
Pavol Genzor
Astrid D Haase
Fred Dyda

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.