Nucleic Acids Research Advance Access originally published online on June 10, 2009
Nucleic Acids Research 2009 37(15):e103; doi:10.1093/nar/gkp498
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Nucleic Acids Research, 2009, Vol. 37, No. 15 e103
© 2009 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Methods Online |
Conditional gene silencing of multiple genes with antisense RNAs and generation of a mutator strain of Escherichia coli
1Proteolysis and Protein Turnover Research Group, Research Institute of Genome-based Biofactory, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517 and 2Graduate School of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589, Japan
*To whom correspondence should be addressed. Tel: +81 11 857 8937; Fax: +81 11 857 8980; Email: n-nakashima{at}aist.go.jp
Received December 2, 2008. Revised May 18, 2009. Accepted May 22, 2009.
In this study, we describe a method of simultaneous conditional gene silencing of up to four genes in Escherichia coli by using antisense RNAs. We used antisense RNAs with paired termini, which carried flanking inverted repeats to create paired double-stranded RNA termini; these RNAs have been proven to have high silencing efficacy. To express antisense RNAs, we constructed four IPTG-inducible vectors carrying different but compatible replication origins. When the lacZ antisense RNA was expressed using these vectors, lacZ expression was successfully silenced by all the vectors, but the expression level of the antisense RNA and silencing efficacy differed depending on the used vectors. All the vectors were co-transformable; the antisense RNAs against lacZ, ackA, pta and pepN were co-expressed, and silencing of all the target genes was confirmed. Furthermore, when antisense RNAs were targeted to the mutator genes mutS, mutD (dnaQ) and ndk, which are involved in DNA replication or DNA mismatch repair, spontaneous mutation frequencies increased over 2000-fold. The resulting mutator strain is useful for random mutagenesis of plasmids. The method provides a robust tool for investigating functional relationships between multiple genes or altering cell phenotypes for biotechnological and industrial applications.