This Article Full Text Full Text (PDF) Other Versions of this Article: IAI.01543-06v1 75/6/2937    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Parthasarathy, G. Articles by Kim, K. S. Search for Related Content PubMed PubMed Citation Articles by Parthasarathy, G. Articles by Kim, K. S.

Flagella Promote Escherichia coli K1 Association with and Invasion of Human Brain Microvascular Endothelial Cells

Division of Pediatric Infectious Diseases, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21287

Received 25 September 2006/ Returned for modification 14 November 2006/ Accepted 6 March 2007

Escherichia coli containing the K1 capsule is the leading cause of gram-negative meningitis, but the pathogenesis of this disease is not completely understood. Recent microarray experiments in which we compared the gene expression profile of E. coli K1 associated with human brain microvascular endothelial cells (HBMEC) to the gene expression profile of E. coli K1 not associated with HBMEC revealed that there was a threefold increase in the expression of the fliI gene, encoding an ATP synthase involved in flagellar synthesis and motility, in HBMEC-associated E. coli. In this study, we examined the role of flagella in E. coli K1 association with and invasion of HBMEC by constructing isogenic flhDC, fliI, fliC, and cheW mutants that represented each class of flagellar genes. Mutations that affected the flagellum structure and flagellum formation (flhDC, fliI, and fliC) resulted in significant defects in motility, as well as in HBMEC association and invasion, compared to the characteristics of the wild-type strain when preparations were examined with or without centrifugation. Transcomplementation with the corresponding genes restored the levels of these mutants to the levels of the parent strain. These findings suggest that the HBMEC association and invasion defects of the mutants are most likely related to flagella and less likely due to their motility defects. This conclusion was supported by our demonstration that the cheW mutant was not motile but was able to associate with and invade HBMEC. In addition, purified recombinant flagellin reduced the association of the wild-type strain with HBMEC by 40%, while it had no effect on the fliC mutant's association with HBMEC. Together, these findings indicate that flagella promote E. coli K1 binding to HBMEC.

Published ahead of print on 19 March 2007.

Editor: J. B. Bliska

This article has been cited by other articles:

• Brown, E. A., Hardwidge, P. R. (2007). Biochemical characterization of the enterotoxigenic Escherichia coli LeoA protein. Microbiology 153: 3776-3784 [Abstract] [Full Text]