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Journal of Bacteriology, February 2009, p. 1258-1267, Vol. 191, No. 4
0021-9193/09/$08.00+0     doi:10.1128/JB.01465-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Toxin-Antitoxin Systems in Escherichia coli Influence Biofilm Formation through YjgK (TabA) and Fimbriae{triangledown}

Younghoon Kim,1 Xiaoxue Wang,1 Qun Ma,1 Xue-Song Zhang,1 and Thomas K. Wood1,2,3*

Artie McFerrin Department of Chemical Engineering,1 Department of Biology,2 Zachry Department of Civil Engineering, Texas A&M University, College Station, Texas 77843-31223

Received 17 October 2008/ Accepted 26 November 2008

The roles of toxin-antitoxin (TA) systems in bacteria have been debated. Here, the role of five TA systems in regard to biofilm development was investigated (listed as toxin/antitoxin: MazF/MazE, RelE/RelB, ChpB, YoeB/YefM, and YafQ/DinJ). Although these multiple TA systems were reported previously to not impact bacterial fitness, we found that deletion of the five TA systems decreased biofilm formation initially (8 h) on three different surfaces and then increased biofilm formation (24 h) by decreasing biofilm dispersal. Whole-transcriptome profiling revealed that the deletion of the five TA systems induced expression of a single gene, yjgK, which encodes an uncharacterized protein; quantitative real-time PCR (qRT-PCR) confirmed consistent induction of this gene (at 8, 15, and 24 h). Corroborating the complex phenotype seen upon deleting the TA systems, overexpression of YjgK decreased biofilm formation at 8 h and increased biofilm formation at 24 h; deletion of yjgK also affected biofilm formation in the expected manner by increasing biofilm formation after 8 h and decreasing biofilm formation after 24 h. In addition, YjgK significantly reduced biofilm dispersal. Whole-transcriptome profiling revealed YjgK represses fimbria genes at 8 h (corroborated by qRT-PCR and a yeast agglutination assay), which agrees with the decrease in biofilm formation upon deleting the five TA systems at 8 h, as well as that seen upon overexpressing YjgK. Sand column assays confirmed that deleting the five TA systems reduced cell attachment. Furthermore, deletion of each of the five toxins increased biofilm formation at 8 h, and overexpression of the five toxins repressed biofilm formation at 8 h, a result that is opposite that of deleting all five TA systems; this suggests that complex regulation occurs involving the antitoxins. Also, the ability of the global regulator Hha to reduce biofilm formation was dependent on the presence of these TA systems. Hence, we suggest that one role of TA systems is to influence biofilm formation.

* Corresponding author. Mailing address: Department of Chemical Engineering, Texas A&M University, 220 Jack E. Brown Bldg., College Station, TX 77843-3122. Phone: (979) 862-1588. Fax: (979) 845-6446. E-mail: Thomas.Wood{at}chemail.tamu.edu

{triangledown} Published ahead of print on 5 December 2008.

Journal of Bacteriology, February 2009, p. 1258-1267, Vol. 191, No. 4
0021-9193/09/$08.00+0     doi:10.1128/JB.01465-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Harrison, J. J., Wade, W. D., Akierman, S., Vacchi-Suzzi, C., Stremick, C. A., Turner, R. J., Ceri, H. (2009). The Chromosomal Toxin Gene yafQ Is a Determinant of Multidrug Tolerance for Escherichia coli Growing in a Biofilm. Antimicrob. Agents Chemother. 53: 2253-2258 [Abstract] [Full Text]  


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