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The Scientific World Journal
Volume 2014, Article ID 428159, 7 pages
Research Article

Expression, Purification, and Functional Analysis of Novel RelE Operon from X. nematophila

1Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, 303 Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA 19104, USA
2School of Biotechnology, Gautam Buddha University, Greater Noida, Yamuna Expressway, Uttar Pradesh 201312, India

Received 21 July 2014; Accepted 10 November 2014; Published 27 November 2014

Academic Editor: Hyung-Sik Won

Copyright © 2014 Jitendra Singh Rathore and Lalit Kumar Gautam. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Bacterial toxin-antitoxin (TA) complexes induce programmed cell death and also function to relieve cell from stress by various response mechanisms. Escherichia coli RelB-RelE TA complex consists of a RelE toxin functionally counteracted by RelB antitoxin. In the present study, a novel homolog of RelE toxin designated as Xn-relE toxin from Xenorhabdus nematophila possessing its own antitoxin designated as Xn-relEAT has been identified. Expression and purification of recombinant proteins under native conditions with GST and Ni-NTA chromatography prove the existence of novel TA module. The expression of recombinant Xn-relE under tightly regulated ara promoter in E. coli Top 10 cells confirms its toxic nature in endogenous toxicity assay. The neutralization activity in endogenous toxicity assay by Xn-relEAT antitoxin confirms its antidote nature when studying the whole TA operon under ara regulated promoter. This study promotes newly discovered TA module to be regarded as important as other proteins of type II toxin-antitoxin system.