Proteasome (Haselbach)

Question 1

What are AAA proteins? What are their main types?

Answer 1

ATPases associated with various cellular Activities:
- molecular motors that (mostly) pull proteins through their central pore
- mostly hexameric
- N-Domain provides substrate recognition
- D-Domain acts as motor domain
- complex assembly / disassembly
- protein disaggregation
- protein degradation

Types:
- Spastin: cytoskeleton remodeling
- NSF: synaptic vesicle fusion
- Hsp104: heat shock response
- YME1: mitochondrial protein QC
- Dyneins: motor protein in flagella

Question 2

Describe the AAA protein structure.

Answer 2

• N-dom.: substrate recognition
• D-dom.: motor dom.
• AAA dom.: well conserved
• Pore loops
• Walker A: ATP binding
• Walker B: ATP hydrolysis
• Sensor dom.

Question 3

Describe the principle of AAA proteins.

Answer 3

While it hydrolyzes ATP, it undergoes a conformational change and one of the protein subunits goes up - in the next step the next subunit goes up and so on.

Pulling of the substrate: the central pore loops change, on pore loops there are bulky hydrophobic AAs - when they go up they stick to whatever AA is in the centre and pull the substrate

If u have a lot of very small side chains, the AAA will not be able to pull it. For one cycle 6 ATPs needed: 1 for each subunit. Also more depending on how long the protein is: normally cca 1000 ATPs/second.

Adaptors needed for the process.

Question 4

How can proteosomes and AAA proteins be studies?

Answer 4

ATP analogs / modified ATPs