Deletion of a previously uncharacterized flagellar-hook-length control gene fliK modulates the sigma54-dependent regulon in Campylobacter jejuni.
A previously unannotated, putative fliK gene was identified in the Campylobacter jejuni genome based on sequence analysis; deletion mutants in this gene had a 'polyhook' phenotype characteristic of fliK mutants in other genera. The mutants greatly overexpressed the sigma(54)-dependent flagellar hook protein FlgE, to form unusual filamentous structures resembling straight flagella in addition to polyhooks. The genome sequence reveals only one gene predicted to encode an orthologue of the NtrC-family activator required for sigma(54)-dependent transcription. Hence, all sigma(54)-dependent genes in the genome would be overexpressed in the fliK mutant together with flgE. Microarray analysis of genome-wide transcription in the mutant showed increased transcription of a subset of genes, often downstream of sigma(54)-dependent promoters identified by a quality-predictive algorithm applied to the whole genome. Assessment of genome-wide transcription in deletion mutants in rpoN, encoding sigma(54), and in the sigma(54)-activator gene flgR, showed reciprocally reduced transcription of genes that were overexpressed in the fliK mutant. The fliA (sigma(28))-dependent regulon was also analysed. Together the data clearly define the roles of the alternative sigma factors RpoN and FliA in flagellar biogenesis in C. jejuni, and identify additional putative members of their respective regulons.
Kamal
Nahid
N
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Dorrell
Nick
N
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
Jagannathan
Aparna
A
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Turner
Susan M
SM
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Constantinidou
Chrystala
C
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Studholme
David J
DJ
Sainsbury Laboratory, John Innes Centre, Norwich NR4 7UH, UK.
Marsden
Gemma
G
Department of Medical Microbiology, St George's Hospital Medical School, Cranmer Terrace, Tooting, London SW17 0RE, UK.
Hinds
Jason
J
Department of Medical Microbiology, St George's Hospital Medical School, Cranmer Terrace, Tooting, London SW17 0RE, UK.
Laing
Ken G
KG
Department of Medical Microbiology, St George's Hospital Medical School, Cranmer Terrace, Tooting, London SW17 0RE, UK.
Wren
Brendan W
BW
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
Penn
Charles W
CW
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D016123:Campylobacter jejuni / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D019295:Computational Biology; D005407:Flagella / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D051877:RNA Polymerase Sigma 54 / Q000378:metabolism*; D018085:Regulon / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012808:Sigma Factor / Q000378:metabolism*
D001426:Bacterial Proteins; C064971:FliA protein, Bacteria; C099486:FliK protein, Bacteria; D012808:Sigma Factor; D051877:RNA Polymerase Sigma 54