The CnuK9E H-NS complex antagonizes DNA binding of DicA and leads to temperature-dependent filamentous growth in E. coli

Sang Hoon Yun; Sang Chun Ji; Heung Jin Jeon; Xun Wang; Si Wouk Kim; Geunu Bak; Younghoon Lee; Heon M Lim

doi:10.1371/journal.pone.0045236

The CnuK9E H-NS complex antagonizes DNA binding of DicA and leads to temperature-dependent filamentous growth in E. coli

PLoS One. 2012;7(9):e45236. doi: 10.1371/journal.pone.0045236. Epub 2012 Sep 13.

Authors

Sang Hoon Yun¹, Sang Chun Ji, Heung Jin Jeon, Xun Wang, Si Wouk Kim, Geunu Bak, Younghoon Lee, Heon M Lim

Affiliation

¹ Department of Biology, College of Biological Sciences and Biotechnology, Chungnam National University, Taejon, Republic of Korea.

Abstract

Cnu (an OriC-binding nucleoid protein) associates with H-NS. A variant of Cnu was identified as a key factor for filamentous growth of a wild-type Escherichia coli strain at 37°C. This variant (CnuK9E) bears a substitution of a lysine to glutamic acid, causing a charge reversal in the first helix. The temperature-dependent filamentous growth of E. coli bearing CnuK9E could be reversed by either lowering the temperature to 25°C or lowering the CnuK9E concentration in the cell. Gene expression analysis suggested that downregulation of dicA by CnuK9E causes a burst of dicB transcription, which, in turn, elicits filamentous growth. In vivo assays indicated that DicA transcriptionally activates its own gene, by binding to its operator in a temperature-dependent manner. The antagonizing effect of CnuK9E with H-NS on DNA-binding activity of DicA was stronger at 37°C, presumably due to the lower operator binding of DicA at 37°C. These data suggest that the temperature-dependent negative effect of CnuK9E on DicA binding plays a major role in filamentous growth. The C-terminus of DicA shows significant amino acid sequence similarity to the DNA-binding domains of RovA and SlyA, regulators of pathogenic genes in Yersinia and Salmonella, respectively, which also show better DNA-binding activity at 25°C.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Substitution
Base Sequence
DNA-Binding Proteins / genetics*
DNA-Binding Proteins / metabolism
Escherichia coli / genetics*
Escherichia coli / growth & development
Escherichia coli / ultrastructure
Escherichia coli Proteins / genetics*
Escherichia coli Proteins / metabolism
Fimbriae Proteins / genetics*
Fimbriae Proteins / metabolism
Gene Expression Regulation, Bacterial*
Molecular Sequence Data
Mutation
Protein Structure, Tertiary
Repressor Proteins / genetics*
Repressor Proteins / metabolism
Sequence Homology, Amino Acid
Transcription, Genetic

Substances

Cnu protein, E coli
DNA-Binding Proteins
DicA protein, E coli
Escherichia coli Proteins
FimG protein, E coli
Repressor Proteins
Fimbriae Proteins

Grants and funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology (2011-0004864). This research was also supported by the Pioneer Research Center Program through the National Research Program of Korea funded by the Ministry of Education, Science and Technology (Grant No. 2008-2000122). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.