MIC 360 Lecture Notes - Lecture 24: Atp Hydrolysis, Protein Folding, Hsp70
Wednesday, April 18, 2018
MIC 360 Class 24 Notes
1. Major Chaperones and Their Interactions with Substrates !
-if you mutate one or a few important general protein chaperone systems!
-Then those proteins mis-folded by increase in temperature cannot be re-folded!
-Biological function will remain as impaired - bacteria will more than likely be killed!
2. Bacterial Chaperone Systems!
2 general systems: !
HSP70 - also named DnaK because it’s found originally not from heat shock analysis
but from the study of particular phage bacteriophage lifestyle!
-mutation at the DnaK cannot support the DNA replication of some bacteriophages !
-Is a general chapterone!
-Can find homologous to humans - means that this system is highly conserved or
that its function is general - in other words it’s very important!
-Is required for the replication of specific bacteriophage!
-Main function of DnaK is as a chaperon!
3. Functional Cycle of DnaK!
-Shown at top = domains of DNaK!
-Two domains - ATPase domain and Substrate binding domain !
-implies that this chaperone requires the hydrolysis of ATP!
-Other domain = it is a chaperone, it will bind to unfolded protein and use energy
derived from ATP to fold this substrate that is a unfolded protein!
-Left = ATPase domain!
-Yellow = unfolded protein substrate!
-When it attaches to binding domain.- ATPase is hydrolyzed!
-DnaJ is a cofactor to assist the folding process!
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Wednesday, April 18, 2018
-The GrpE is another cofactor to replace the ADP from this ATPase domain!
-ADP is a product of ATP hydrolysis, one phosphoryl group is released and
generates ADP!
-ADP will be replaced by a new ATP under the assistance of the GrpE
protein!
-Finishes one cycle!
-Comes back to active form for the binding of another unfolded protein!
4. The GroEL-GroES chaperone Machine!
-GroEL = one protein, GroES is another protein!
-This chaperone system has to wiat for the protein folding until that particular
protein is completely translated!
-THis is because these two - GroEL is the larger subunit - forms a layer complex;
one layer with seven GroEL and the other with 7 GroES = heptamer complex!
-There is a hollow complex in the center where the denatured protein can enter!
-Champer is two heptamers of GroEL ring!
-ON the other hand GroES fors a heptamer = small subunit!
-Makes a leaflike complex. !
-Take the 2 layer GroEL that accepts unfolded protein into hollow channel, GroES
puts the lid onto the cylinder !
-Unfolded protein will be folded inside this champer!
-Then it will be released out after it is folded!
-In the meantime, because this unfolded protein only enters into one half of the
chamber, bottom half still remains empty!
-When this is capped, another unfolded protein can enter the opposite champer,
the top lid opens and another lid gets added to the protein!
-Folded protein goes out, and now another cycle of unfolded protein takes
place!
-Cannot fold them simultaneously - just one at a time!
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Document Summary
Mic 360 class 24 notes: major chaperones and their interactions with substrates. If you mutate one or a few important general protein chaperone systems. Then those proteins mis-folded by increase in temperature cannot be re-folded. Biological function will remain as impaired - bacteria will more than likely be killed: bacterial chaperone systems. Hsp70 - also named dnak because it"s found originally not from heat shock analysis but from the study of particular phage bacteriophage lifestyle. Mutation at the dnak cannot support the dna replication of some bacteriophages. Can nd homologous to humans - means that this system is highly conserved or that its function is general - in other words it"s very important. Is required for the replication of speci c bacteriophage. Main function of dnak is as a chaperon: functional cycle of dnak. Shown at top = domains of dnak. Two domains - atpase domain and substrate binding domain. Implies that this chaperone requires the hydrolysis of atp.
