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Title: Cas9-mediated genome editing in the methanogenic archaeon Methanosarcina acetivorans

Although Cas9-mediated genome editing has proven to be a powerful genetic tool in eukaryotes, its application in Bacteria has been limited because of inefficient targeting or repair; and its application to Archaea has yet to be reported. Here we describe the development of a Cas9-mediated genome-editing tool that allows facile genetic manipulation of the slow-growing methanogenic archaeon Methanosarcina acetivorans. Introduction of both insertions and deletions by homology-directed repair was remarkably efficient and precise, occurring at a frequency of approximately 20% relative to the transformation efficiency, with the desired mutation being found in essentially all transformants examined. Off-target activity was not observed. We also observed that multiple single-guide RNAs could be expressed in the same transcript, reducing the size of mutagenic plasmids and simultaneously simplifying their design. Cas9-mediated genome editing reduces the time needed to construct mutants by more than half (3 vs. 8 wk) and allows simultaneous construction of double mutants with high efficiency, exponentially decreasing the time needed for complex strain constructions. Furthermore, coexpression the nonhomologous end-joining (NHEJ) machinery from the closely related archaeon, Methanocella paludicola, allowed efficient Cas9-mediated genome editing without the need for a repair template. The NHEJ-dependent mutations included deletions ranging from 75 to 2.7 kbmore » in length, most of which appear to have occurred at regions of naturally occurring microhomology. In conclusion, the combination of homology-directed repair-dependent and NHEJ-dependent genome-editing tools comprises a powerful genetic system that enables facile insertion and deletion of genes, rational modification of gene expression, and testing of gene essentiality.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1]
  1. Univ. of Illinois at Urbana–Champaign, Urbana, IL (United States)
Publication Date:
Grant/Contract Number:
FG02-02ER15296
Type:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 114; Journal Issue: 11; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Univ. of Illinois at Urbana–Champaign, Urbana, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; Cas9; Archaea; methanogens; Methanosarcina; genetics
OSTI Identifier:
1345844
Alternate Identifier(s):
OSTI ID: 1465485