《微生物学》课程PPT课件讲稿（英文版）Lecture 4

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