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Flagelos bacterianos
Spirillum serpens, uma bactéria
com flagelo lofotriquio
Vibrio metchnikovii, uma bactéria
com flagelo monotriquio
Proteus vulgaris, uma bactéria
com flagelo peritriquio
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Figure 4 Three-dimensional image reconstructions of the distal end of a flagellar filament, with the filament cap at its distal end.
(a) Lateral view, with the front half removed. Note the central channel, which suddenly widens at the distal end just beneath the
cap. (b) Lateral view, corresponding to direction 1 in panel c. The subunits of the pentameric cap are labeled with Greek letters;
only the α, β, and ε subunits can be seen in this view. Note the large cavity below subunit α, which is believed to be the point of
assembly of the most recently arrived flagellin subunit. (c) Top view of the pentameric cap. MacNab
Flagelo vs F0F1ATP Sintetase
EM reconstructions of basal bodies of the flagellum and type III injectisome of Salmonella. (A)
Model of the bacterial hook-basal-body complex based on EM reconstructions (Derosier
2006).
Erhardt M et al. Cold Spring Harb Perspect Biol
2010;2:a000299
©2010 by Cold Spring Harbor Laboratory Press
O flagelo é codificado por mais de 50 genes e tem
muitas partes homólogas a outros sistemas
Type III Secretion apparatus
Axial protein family
Type II secretion
Ion transport
Signal transduction
Steps in assembly of the bacterial flagellum.
©2010 by Cold Spring Harbor Laboratory Press
Erhardt M et al. Cold Spring Harb Perspect Biol
2010;2:a000299
Flagellar Function
Guide bacteria in a direction in response to
external stimulus:
chemical stimuli – chemotaxis; positive and negative
light stimuli – phototaxis
Signal sets flagella into rotary motion clockwise or
counterclockwise:
counterclockwise – results in smooth linear direction –
run
clockwise - tumbles
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Movimento do flagelo
Insert figure 4.5
Chemotaxis in bacteria
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Axial Filaments
• Periplasmic, internal flagella, enclosed
between cell wall and cell membrane of
spirochetes
• Produce cellular motility by contracting and
imparting twisting or flexing motion
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Fimbriae
• Fine, proteinaceous, hairlike bristles from
the cell surface
• Function in adhesion to other cells and
surfaces
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Pili
• Rigid tubular structure made of pilin protein
• Found only in Gram negative cells
• Function to join bacterial cells for partial DNA
transfer called conjugation
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