Microbial Locomotion

Question 1

What is the flagella?

Answer 1

Long, thin appendage of bacteria.

Its role is motility.

Question 2

What is the basic operation of the flagella?

Answer 2

It functions by rotation to push or pull the cell through a liquid medium.

Question 3

What is the structure of a flagellum?

Answer 3

1.	Filament
	Rigid helical structure
	Rotates (like a propeller)
	Contains flagellin: protein subunit, polymerized to form filament
2.	Hook
	Single protein
	Attaches filament to basal body
3.	Basal body
	Rod held by several rings

Question 4

What are the rings found on the basal body? What are their roles?

Answer 4

*	In gram-negative
	L ring attaches basal body to LPS
	P ring: peptidoglycan
•	L ring and P ring only have structural role: stabilize the basal body)
	MS ring and C ring: “motor”, propeller

• In gram-positive
   MS ring and C ring

Question 5

What proteins compose the MS ring and the C ring?

Answer 5

• Mot proteins

- Fli proteins

Question 6

What are the roles of the MS ring and C ring proteins? What is the energetic demand of each?

Answer 6

1.	Mot proteins
	Function as the actual “motor”
	Flagellar motor
	These proteins rotate MS and C rings
-	By proton pumping from cytoplasm (no ATP required)

2. Fli proteins
    “Switch” of the motor
    Can reverse the rotation of the flagella (changes direction of rotation of flagella)
    Gives the ability to go forward or backward
   - About 1000 H+ pumped per single rotation  energetically consuming process