Université de Fribourg

Hook length of the bacterial flagellum is optimized for maximal stability of the flagellar bundle

Spöring, Imke ; Martinez, Vincent A. ; Hotz, Christian ; Schwarz-Linek, Jana ; Grady, Keara L. ; Nava-Sedeño, Josué M. ; Vissers, Teun ; Singer, Hanna M. ; Rohde, Manfred ; Bourquin, Carole ; Hatzikirou, Haralampos ; Poon, Wilson C. K. ; Dufour, Yann S. ; Erhardt, Marc

In: PLOS Biology, 2018, vol. 16, no. 9, p. e2006989

Most bacteria swim in liquid environments by rotating one or several flagella. The long external filament of the flagellum is connected to a membrane-embedded basal body by a flexible universal joint, the hook, which allows the transmission of motor torque to the filament. The length of the hook is controlled on a nanometer scale by a sophisticated molecular ruler mechanism. However, why its...

Université de Fribourg

RflM mediates target specificity of the RcsCDB phosphorelay system for transcriptional repression of flagellar synthesis in Salmonella enterica: Repression of flhDC transcription by a RcsB-RflM complex

Kühne, Caroline ; Singer, Hanna M. ; Grabisch, Eva ; Codutti, Luca ; Carlomagno, Teresa ; Scrima, Andrea ; Erhardt, Marc

In: Molecular Microbiology, 2016, p. -

The bacterial flagellum enables directed movement of Salmonella enterica towards favorable conditions in liquid environments. Regulation of flagellar synthesis is tightly controlled by various environmental signals at transcriptional and post- transcriptional levels. The flagellar master regulator FlhD₄C₂ resides on top of the flagellar transcriptional hierarchy and is under...

Université de Fribourg

The Salmonella Spi1 virulence regulatory protein HilD directly activates transcription of the flagellar master operon flhDC

Singer, Hanna M. ; Kühne, Caroline ; Deditius, Julia A. ; Hughes, Kelly T. ; Erhardt, Marc

In: Journal of Bacteriology, 2014, vol. 196, no. 7, p. 1448–1457

Infection of intestinal epithelial cells is dependent on the Salmonella enterica serovar Typhimurium pathogenicity island 1 (Spi1)-encoded type III injectisome system and flagellar motility. Thus, the expression of virulence and flagellar genes is subject to tight regulatory control mechanisms in order to ensure the correct spatiotemporal production of the respective gene products. In this work,...

Université de Fribourg

RflM functions as a transcriptional repressor in the autogenous control of the Salmonella flagellar master operon flhDC

Singer, Hanna M. ; Erhardt, Marc ; Hughes, Kelly T.

In: Journal of Bacteriology, 2013, vol. 195, no. 18, p. 4274–4282

Motility of bacteria like Salmonella enterica is a highly regulated process that responds to a variety of internal and external stimuli. A hierarchy of three promoter classes characterizes the Salmonella flagellar system, and the onset of flagellar gene expression depends on the oligomeric regulatory complex and class 1 gene product FlhD4C2. The flhDC promoter is a target for a broad range of...

Université de Fribourg

Selective purification of recombinant neuroactive peptides using the flagellar type III secretion system

Singer, Hanna M. ; Erhardt, Marc ; Steiner, Andrew M. ; Zhang, Min-Min ; Yoshikami, Doju ; Bulaj, Grzegorz ; Olivera, Baldomero M. ; Hughes, Kelly T.

In: mBio, 2012, vol. 3, no. 3, p. e00115-12t

The structure, assembly, and function of the bacterial flagellum involves about 60 different proteins, many of which are selectively secreted via a specific type III secretion system (T3SS) (J. Frye et al., J. Bacteriol. 188:2233–2243, 2006). The T3SS is reported to secrete proteins at rates of up to 10,000 amino acid residues per second. In this work, we showed that the flagellar T3SS of...

Université de Fribourg

An infrequent molecular ruler controls flagellar hook length in Salmonella enterica

Erhardt, Marc ; Singer, Hanna M ; Wee, Daniel H ; Keener, James P ; Hughes, Kelly T

In: The EMBO Journal, 2011, vol. 30, no. 14, p. 2948 - 2961

The bacterial flagellum consists of a long external filament connected to a membrane-embedded basal body at the cell surface by a short curved structure called the hook. In Salmonella enterica, the hook extends 55 nm from the cell surface. FliK, a secreted molecular ruler, controls hook length. Upon hook completion, FliK induces a secretion-specificity switch to filament-type substrate secretion....