Scribe.Lecture 29.docx

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University of Toronto St. George
Cell and Systems Biology
William Navarre

Lecture 29 5 1. flagella & T3SS share an evolutionary past (thus look very similar) 2. basal body consist of 3 main rings 1. L ring – spans OM 2. P ring – spans periplasm 3. MS ring – spans IM 1. contains motor switch proteins 2. rotor is the part of the flagella that moves 3. the stationary stator composed of Mot proteins 4. rings rotate w/in the stationary protein at a rate of 270 revolutions/sec (very fast) 3. basal body anchors the hook 1. the hook is the flexible element that pivots around when the motor starts running 4. filaments are very long, composed of a single protein, flagellin 5. to assemble the filament and the hook, the components are secreted through the apparatus (secretion system) 1. components are secreted through the apparatus and built up w the aid of the cap at the top 6. ATPase is required for the assembly of the flagella, but not required for the actual function 7. the actual rotation of the flagella is powered by PMF 6 8. PMF moves protons through the stationary Mot proteins that have proton channels through them 9. they use this NRG to power the rotation of the machine 10. for 1 turn of the flagella requires 1000 protons (very fast) 1. bacteria can swim up to 60x their length/sec 7 11. assembly from the inside out 12. MS ring & motor proteins assembled first 13. build components in the OM 14. hook 15. filament last 16. how to control what happens first? 1. after assembled ring, need to secrete hook before filament (bacteria have mechanisms to control this) – secretion hierarchy 2. bacteria self-monitors its secretion capabilities 3. before the assembly apparatus is complete, there are regulatory proteins inside the cytoplasm that through their interactions, secretion is blocked 4. once apparatus is done, proteins are released (ex. TF), and flagella proteins are producted 1. flagella components are not made until apparatus is assembled 8 17. some bacteria have 1 flagella 18. some have a lot of flagella at one pole 19. some have flagella everywhere 20. w only one, they move by changing rotation of the flagella forwards or backwards or stop to reorient 21. w many flagella, and want to move forward, the many flagella form a bundle and form CCW rotation all at the same time 1. if stop, and flagella get pushed apart and each do their own flagellar rotation 1. this causes a tumbling motion, allowing them to change direction, and then after, rebundle their flagella and move in another direction 9 22. bacteria also use flagella for swarming 23. swarming happens when bacteria find themselves on a solid surface w some moisture for the flagella to work 24. bacteria become hyperflagellated to overcome friction of moving over a solid surface 11 25. slime secretion 1. can be true bc we know that polysaccharide synthesis is needed for gliding 2. but slime needs ATP while we know that gliding is driven by PMF 26. focal adhesion 1. focal adhesion complexes anchor bacteria to a surface 2. motor proteins push along the FACs, and bc they can also interact w the cytoskeleton, as the
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