Lecture 4 4. 10 Flagella and motility 4. 11 Gliding Motility 4. 12 Bacterial Responses: Chemotaxis Phototaxis, and other Taxes 4.13 Bacterial cell surface structures and cell Inclusions ·4.14 Gas Vesicles ·4.15 Endospores
Lecture 4 • 4.10 Flagella and Motility • 4.11 Gliding Motility • 4.12 Bacterial Responses: Chemotaxis, Phototaxis, and other Taxes • 4.13 Bacterial Cell Surface Structures and Cell Inclusions • 4.14 Gas Vesicles • 4.15 Endospores
The Flagellum 14 nm Outer membrane LPS) L Ring Periplasm Peptidoglycan Cytoplasmic Fli proteins 1000 H+/rotation membrane (motor switch) Mot protein protein 45 nm 40 genes involved
The Flagellum 1000 H+ / rotation > 40 genes involved
Flagellar motion >40 genes involved. include regulators movement driven by propeller-like rotation can propel cells up to 60 cell lengths/s equivalent of 2. 5x faster than a cheetah! expensive process: must confer strong selective advantage
Flagellar motion • > 40 genes involved, include regulators • movement driven by propeller-like rotation • can propel cells up to 60 cell lengths/s • equivalent of 2.5x faster than a cheetah! • expensive process: must confer strong selective advantage
Steps in biosynthesis of flagella Filament synthesis Late hook Outer Early hook Cap Filament nembrane Motor MS ring proteins Pring Lring Peptidoglycan Cytoplasmic membrane
Steps in Biosynthesis of Flagella
Types of Flagellar Arrangements (a Peritrichous Tumble- flagella pushed A apart (CW rotation Bundled flagella (CCW rotation) Run < y Flagella bundled (CCW rotation
Run Types of Flagellar Arrangements
(b) Polar: reversible flagella 八八 CCW rotation CW rotation Polar: unidirectional flagella Cell stops, CW rotation reorients CW rotation
Motility in non-aqueous environments 1. polysaccharide"slime layer secreted slime used to pull cell along a surface 2. special proteins in the outer membrane act te feet, which are activated by inner membrane proteins resulting in"crawling
Motility in non-aqueous environments 1. polysaccharide “slime layer” — secreted slime used to pull cell along a surface 2. special proteins in the outer membrane act like feet, which are activated by inner membrane proteins resulting in “crawling
H ⊥ Cytoplasmic membrane Peptidoglycan Outer membrane (b) i Movement of outer membrane protein Movement of cell
Absence of chemical attractant Tumble Run Fig 4.46a
Absence of chemical attractant Fig. 4.46a
Presence of chemical attractant Tumble Attractant R Fig. 4. 46b chemical gradient sensed in a temporal manner
Presence of chemical attractant Fig. 4.46b chemical gradient sensed in a temporal manner
