bacteria shapes and arrangement explained

These results, although preliminary, indicate that motility is required for infection in vivo, irrespective of their route of infection (M. Motaleb, P.

Artificially infected Ixodes scapularis ticks were also unable to transmit the mutant organism from their intestines to experimental mice. burgdorferi from the flaB inoculated mice tissues also failed even when the animals received 200 times the ID 50 (M. burgdorferi targeted mutants isolated independently in the periplasmic flagellar protein encoded by flaB found the following: the flaB mutants were not infectious in mice at an infectious dose 50 (ID 50) of 5 × 10 3 cells/mouse. For example, preliminary results with two B. In addition, mounting evidence suggests a substantial link between motility and virulence in B. burgdorferi. In these species of spirochetes, where the flagella serve both skeletal and motile functions, shape and motility are intimately connected.

Moreover, several models of spirochete locomotion indicate that the skeletal function of the periplasmic flagella is essential for their motility ( 3,6,11–13). burgdorferi), the flagella are also skeletal organelles cells lacking flagella or with straight flagella have altered shapes, and these mutants are also nonmotile ( 6–10). In contrast, in other species, such as Leptospira interrogans and Borrelia burgdorferi ( B. Species such as Spirochaeta aurantia and Treponema primitia swim by a mechanism in which the flagella do not deform the cell cylinder and do not influence cell shape ( 4,5). As in other bacteria, the flagella serve an obvious motile function as they are driven by rotary motors at their base, but, in spirochetes, these organelles rotate between the outer membrane and cell cylinder ( 3). Depending on the species, the final shape of a spirochete is either helical or a flat wave. Although spirochetes vary tremendously with respect to habitat, size, number of periplasmic flagella attached at each end, and their mechanics of swimming, DNA sequence analysis indicates that they all evolved from a primordial protospirochete ( 1–3). Although the flagella of these bacteria are structurally similar to those of other species, they are encased within the periplasmic space, which lies between the cell wall complex (i.e., cell cylinder) and the outer membrane. Spirochetes constitute a unique group of motile bacteria, with some members being highly virulent in humans. This approach is applicable to a variety of other structures in which the shape of the composite system is markedly different from that of the individual components, such as coiled-coil domains in proteins and the eukaryotic axoneme. burgdorferi is completely determined by the elastic properties of the flagella and cell body. These results imply relative stiffnesses of the two components, which confirm the predictions of the model and show that the morphology of B. Optical trapping experiments were used to measure directly the mechanical properties of these spirochetes. The mathematical model suggests that the larger waveform flagellum is the more relevant for determining the shape of B. Observations of purified periplasmic flagella show two flagellar conformations. A mathematical model is developed here that accounts for the elastic coupling of the flagella to the cell cylinder and shows that the flat-wave morphology is in fact a natural consequence of the geometrical and material properties of the components. burgdorferi), which mechanically couples its motility organelles, helical flagella, to its rod-shaped cell body, producing a striking flat-wave morphology. A prime example is the Lyme disease spirochete, Borrelia burgdorferi ( B. The mechanisms that determine bacterial shape are in many ways poorly understood.

Bacteria shapes and arrangement explained