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Mol Cell Proteomics. 2014 Jun;13(6):1485-94. doi: 10.1074/mcp.M113.035667. Epub 2014 Apr 1.

Identification of bacterial factors involved in type 1 fimbria expression using an Escherichia coli K12 proteome chip.

Author information

1
From the ‡Graduate Institute of Systems Biology and Bioinformatics, National Central University, Jhongli City, Taiwan;
2
§Institute of Molecular Medicine, National Cheng Kung University Medical College, Tainan City, Taiwan; ¶Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City, Taiwan; ‖Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan City, Taiwan;
3
¶Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City, Taiwan;
4
§Institute of Molecular Medicine, National Cheng Kung University Medical College, Tainan City, Taiwan; ‖Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan City, Taiwan;
5
**Department of Nutrition and Health Sciences, Kainan University. No. 1, Kainan Road, Luzhu Township, Taoyuan Country, Taiwan.
6
From the ‡Graduate Institute of Systems Biology and Bioinformatics, National Central University, Jhongli City, Taiwan; cchen103@gmail.com.

Abstract

Type 1 fimbriae are filamentous structures on Escherichia coli. These structures are important adherence factors. Because binding to the host cells is the first step of infection, type 1 fimbria is an important virulence factor of pathogenic E. coli. Expression of type 1 fimbria is regulated by a phase variation in which each individual bacterium can alternate between fimbriated (phase-ON) and nonfimbriated (phase-OFF) states. The phase variation is regulated by the flipping of the 314-bp fimS fragment, which contains the promoter driving the expression of the genes required for the synthesis of type 1 fimbria. Thus, the bacterial proteins able to interact with fimS are likely to be involved in regulating the expression of type 1 fimbria. To identify novel type 1 fimbria-regulating factors, we used an E. coli K12 proteome chip to screen for the bacterial factors able to interact with a 602-bp DNA fragment containing fimS and its adjacent regions. The Spr protein was identified by the proteome chip-based screening and further confirmed to be able to interact with fimS by electrophoretic mobility shift assay. Deletion of spr in the neonatal meningitis E. coli strain RS218 significantly increased the ratio of the bacterial colonies that contained the type 1 fimbria phase-ON cells on agar plates. In addition, Spr interfered with the interactions of fimS with the site-specific recombinases, FimB and FimE, which are responsible for mediating the flipping of fimS. These results suggest that Spr is involved in the regulation of type 1 fimbria expression through direct interaction with the invertible element fimS. These findings facilitate our understanding of the regulation of type 1 fimbria.

PMID:
24692643
PMCID:
PMC4047468
DOI:
10.1074/mcp.M113.035667
[Indexed for MEDLINE]
Free PMC Article

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