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Transformations in flagellar structure of Rhodobacter sphaeroides and possible relationship to changes in swimming speed.
Armitage, J P; Pitta, T P; Vigeant, M A; Packer, H L; Ford, R M.
Afiliação
  • Armitage JP; Microbiology Unit, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom. armitage@bioch.ox.ac.uk
J Bacteriol ; 181(16): 4825-33, 1999 Aug.
Article em En | MEDLINE | ID: mdl-10438751
Rhodobacter sphaeroides is a photosynthetic bacterium which swims by rotating a single flagellum in one direction, periodically stopping, and reorienting during these stops. Free-swimming R. sphaeroides was examined by both differential interference contrast (DIC) microscopy, which allows the flagella of swimming cells to be seen in vivo, and tracking microscopy, which tracks swimming patterns in three dimensions. DIC microscopy showed that when rotation stopped, the helical flagellum relaxed into a high-amplitude, short-wavelength coiled form, confirming previous observations. However, DIC microscopy also revealed that the coiled filament could rotate slowly, reorienting the cell before a transition back to the functional helix. The time taken to reform a functional helix depended on the rate of rotation of the helix and the length of the filament. In addition to these coiled and helical forms, a third conformation was observed: a rapidly rotating, apparently straight form. This form took shape from the cell body out and was seen to form directly from flagella that were initially in either the coiled or the helical conformation. This form was always significantly longer than the coiled or helical form from which it was derived. The resolution of DIC microscopy made it impossible to identify whether this form was genuinely in a straight conformation or was a low-amplitude, long-wavelength helix. Examination of the three-dimensional swimming pattern showed that R. sphaeroides changed speed while swimming, sometimes doubling the swimming speed between stops. The rate of acceleration out of stops was also variable. The transformations in waveform are assumed to be torsionally driven and may be related to the changes in speed measured in free-swimming cells. The roles of and mechanisms that may be involved in the transformations of filament conformations and changes in swimming speed are discussed.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Rhodobacter sphaeroides / Flagelos Tipo de estudo: Prognostic_studies Idioma: En Revista: J Bacteriol Ano de publicação: 1999 Tipo de documento: Article País de afiliação: Reino Unido País de publicação: Estados Unidos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Rhodobacter sphaeroides / Flagelos Tipo de estudo: Prognostic_studies Idioma: En Revista: J Bacteriol Ano de publicação: 1999 Tipo de documento: Article País de afiliação: Reino Unido País de publicação: Estados Unidos