Dataset Information

Forces and torques on rotating spirochete flagella.

ABSTRACT: Spirochetes are a unique group of motile bacteria that are distinguished by their helical or flat-wave shapes and the location of their flagella, which reside within the tiny space between the bacterial cell wall and the outer membrane (the periplasm). In Borrelia burgdorferi, rotation of the flagella produces cellular undulations that drive swimming. How these shape changes arise due to the forces and torques that act between the flagella and the cell body is unknown. It is possible that resistive forces come from friction or from fluid drag, depending on whether or not the flagella are in contact with the cell wall. Here, we consider both of these cases. By analyzing the motion of an elastic flagellum rotating in the periplasmic space, we show that the flagella are most likely separated from the bacterial cell wall by a lubricating layer of fluid. This analysis then provides drag coefficients for rotation and sliding of a flagellum within the periplasm.

SUBMITTER: Yang J

PROVIDER: S-EPMC3484371 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature

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Forces and torques on rotating spirochete flagella.

Yang Jing J Huber Greg G Wolgemuth Charles W CW

Physical review letters 20111223 26

Spirochetes are a unique group of motile bacteria that are distinguished by their helical or flat-wave shapes and the location of their flagella, which reside within the tiny space between the bacterial cell wall and the outer membrane (the periplasm). In Borrelia burgdorferi, rotation of the flagella produces cellular undulations that drive swimming. How these shape changes arise due to the forces and torques that act between the flagella and the cell body is unknown. It is possible that resist ...[more]

PMID: 22243185

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Project description:Bacteriophage 7-7-1, a member of the Myoviridae family, infects the soil bacterium Agrobacterium sp. H13-3. Infection requires attachment to actively rotating bacterial flagellar filaments, with flagellar number, length, and rotation speed being important determinants for infection efficiency. To identify secondary receptor(s) on the cell surface, we isolated motile, phage-resistant Agrobacterium sp. H13-3 transposon mutants. Transposon insertion sites were pinpointed using arbitrary-primed polymerase chain reaction and bioinformatics analyses. Three genes were recognized, whose corresponding proteins had the following computationally predicted functions: AGROH133_07337, a glycosyl transferase, AGROH133_13050, a UDP-glucose 4-epimerase, and AGROH133_08824, an integral cytoplasmic membrane protein. The first two gene products are part of the lipopolysaccharide (LPS) synthesis pathway, while the latter is predicted to be a relatively small (13.4 kDa) cytosolic membrane protein with up to four transmembrane helices. Phenotypes of transposon mutants were verified by complementation and site-directed mutagenesis. Additional characterization of motile, phage resistant mutants is also described. Given these findings, we propose a model for Agrobacterium sp. H13-3 infection by bacteriophage 7-7-1 where the phage initially attaches to the flagellar filament and is propelled down towards the cell surface by clockwise flagellar rotation. The phage then attaches to and degrades the LPS to reach the outer membrane, and ejects its DNA into the host using its syringe-like contractile tail. We hypothesize that the integral membrane protein plays an important role in events following viral DNA ejection or in LPS processing and/or deployment. The proposed two-step attachment mechanism may be conserved among other flagellotropic phages infecting Gram-negative bacteria.IMPORTANCE Flagellotropic bacteriophages belong to tailed phage order Caudovirales, which are the most abundant in the virome. While it is known that these viruses adhere to the bacterial flagellum and use flagellar rotation to reach the cell surface, their infection mechanisms are poorly understood. Characterizing flagellotropic phage-host interactions is crucial to understanding how microbial communities are shaped. Using a transposon mutagenesis approach combined with a screen for motile, phage-resistant mutants, we identified lipopolysaccharides as the secondary cell surface receptor for phage 7-7-1. This is the first cell surface receptor identified for flagellotropic phages. One hypothetical membrane protein was also recognized as essential for infection. These new findings, together with previous results, culminated in an infection model for phage 7-7-1.

Dataset Information

Forces and torques on rotating spirochete flagella.

Publications

Forces and torques on rotating spirochete flagella.

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