This Article Full Text Full Text (PDF) 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 Lee, H. J. Articles by Hughes, K. T. Search for Related Content PubMed PubMed Citation Articles by Lee, H. J. Articles by Hughes, K. T.

Posttranscriptional Control of the Salmonella enterica Flagellar Hook Protein FlgE

Department of Biology, University of Utah, Salt Lake City, Utah 84112

Received 10 January 2006/ Accepted 14 February 2006

Previous work suggested that the FlgE (flagellar hook subunit) protein in Salmonella enterica serovar Typhimurium was posttranscriptionally regulated in response to the stage of flagellar assembly. Specifically, the FlgE protein could be detected in flagellar mutants defective at the stages of assembly before or after rod assembly but not in rod assembly mutants, yet flgE mRNA levels were unaffected. To elucidate posttranscriptional mechanisms involved in the coupling of flgE gene expression to hook assembly, the RNA sequences at the 5' and 3' ends of the flgE-containing mRNA processed from the large flgBCDEFGHIJKL operon were determined by rapid amplification of cDNA ends, and secretion of the FlgE protein in different flagellar assembly mutant strains was analyzed. The sequences 5' and 3' of the flgE gene where RNA processing occurred was within 15 bases upstream of the flgD stop codon and at bases 145 to 147 downstream of the flgF start codon, respectively. The ribosome binding site of the flgD gene was found to be inhibitory to flgE translation in strains deleted for the upstream flgD gene, unless the region 15 bases upstream of the flgD stop codon was present. Secretion of FlgE into the periplasm was monitored using ß-lactamase (Bla) fusions as a periplasm-specific reporter, which conferred resistance to ampicillin when FlgE-Bla was secreted into the periplasm. Using this assay, we found that the effect of rod assembly mutants on FlgE levels was due to FlgE turnover in the periplasm and that the FliE rod component protein was required for efficient FlgE-Bla secretion.

This article has been cited by other articles:

• McCann, J. R., McDonough, J. A., Pavelka, M. S., Braunstein, M. (2007). beta-Lactamase can function as a reporter of bacterial protein export during Mycobacterium tuberculosis infection of host cells. Microbiology 153: 3350-3359 [Abstract] [Full Text]