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Series GSE42863 Query DataSets for GSE42863
Status Public on Dec 09, 2013
Title Flagellar export apparatus protein, FliH, is involved in post-transcriptional regulation of FlaB, motility and virulence of the relapsing fever spirochete Borrelia hermsii
Platform organisms Borrelia hermsii; Francisella tularensis; Coxiella burnetii; Rickettsia prowazekii; Burkholderia mallei; Brucella suis
Sample organism Borrelia hermsii
Experiment type Expression profiling by array
Summary Spirochetes are long, thin, motile, helical or flat wave bacteria that are unique among the prokaryotes by having flagella or axial filaments confined to an internal periplasmic space. These flagella are complex organelles that can play major roles in bacterial pathogenicity and are used as propellers allowing bacteria to move through liquids, viscous environments or along surfaces. While most bacteria species use transcriptional regulatory cascades to regulate the synthesis and assembly of their flagella, spirochetes employ an unusual post-transcriptional mechanism. Using next generation sequencing, we characterized a natural mutant of the relapsing fever spirochete Borrelia hermsii lacking the flagellar export apparatus protein FliH. The mutant was non-motile, uncoiled and straight compared to the wild-type spirochetes. The B. hermsii fliH mutant produced only a residual amount of the major flagellin protein FlaB, which was correlated with a reduced number of periplasmic flagella. The amounts of flaB transcript were comparable in the fliH mutant and the wild-type strain. The synthesis of FlaB, the motility and the infectivity of the fliH mutant were rescued by trans-complementation. This report reveals a new function for FliH, and we propose that this regulator of the flagellar export apparatus influences the post-transcriptional processing of the flagella, motility and virulence of the relapsing fever spirochete Borrelia hermsii.
Spirochetes are bacteria characterized in part by rotating periplasmic flagella that impart their flat-wave morphology and motility. While other bacteria rely on a transcriptional cascade to regulate the expression of motility genes, spirochetes employ posttranscriptional mechanism(s) that are only partially known. In the present study, we characterize a non-motile mutant of the relapsing fever spirochete Borrelia hermsii that was straight, non-motile and deficient in flagella. We used next generation DNA sequencing of the mutant’s genome, which when compared to the wild-type genome identified a 142 bp deletion in the chromosomal gene encoding the flagellar export apparatus protein FliH. Immunoblot and transcriptome analyses showed that the mutant phenotype was linked to the posttranscriptional deficiency in the synthesis of the major flagellar filament core protein FlaB. The turnover of the residual pool of FlaB produced by the fliH mutant was comparable to the wild-type spirochete while the amount of FlaA was similar to the wild-type level. The non-motile mutant was not infectious in mice and its inoculation did not induce an antibody response. Trans-complementation of the mutant with an intact fliH gene restored the synthesis of FlaB, a normal morphology, motility and infectivity in mice. Therefore, we propose that the flagellar export apparatus protein regulates motility of B. hermsii at the posttranscriptional level by influencing the synthesis of FlaB.
 
Overall design Borrelia hermsii wild type vs. motility mutant
 
Contributor(s) Guyard C, Raffel SJ, Schrumpf ME, Dahlstrom E, Sturdevant D, Ricklefs SM, Martens C, Hayes SF, Porcella SF, Schwan TG
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Submission date Dec 12, 2012
Last update date Dec 10, 2013
Contact name Dan Sturdevant
E-mail(s) [email protected]
Phone 4063639248
Organization name NIH
Department NIAID
Lab RTS
Street address 903 S 4th street
City Hamilton
State/province MT
ZIP/Postal code 59840
Country USA
 
Platforms (1)
GPL7246 Affymetrix RML Custom Pathogenic chip 2
Samples (24)
GSM1052217 mutant-batch-1-rep-1
GSM1052218 mutant-batch-1-rep-2
GSM1052219 mutant-batch-1-rep-3
Relations
BioProject PRJNA183673

Download family Format
SOFT formatted family file(s) SOFTHelp
MINiML formatted family file(s) MINiMLHelp
Series Matrix File(s) TXTHelp

Supplementary file Size Download File type/resource
GSE42863_RAW.tar 45.0 Mb (http)(custom) TAR (of CEL, CHP)
Processed data included within Sample table
Processed data provided as supplementary file

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