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Heat shock proteins
Heat shock proteins (HSPs) help maintain protein structure and prevent aggregation. They are classified by molecular weight and function. HSP100, HSP90, HSP70, HSP60 and small HSPs aid in protein folding, transport, and solubilization. When stressed, proteins can unfold but HSPs bind to prevent aggregation and allow refolding. HSPs are more stable due to strong hydrogen bonds and packing that maintain their structure even in stressful conditions.
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Heat shock proteins
- 1. HEAT SHOCK PROTIENS -Purvi Shah
- 2. Proteins are themajor components of living organisms and perform a wide range of essential functions in cells Proteins regulate metabolic activity, catalyze biochemical reactions and maintain structural integrity of cells and organisms Proteins
- 3. Structural Levels ofProteins Primary Secondary
- 4. Protein Denaturation Theactivity of a protein depends on its three-dimensional structure. Intramolecular bonds, especially hydrogen bonds, maintain the structure. Hydrogen bonds may break when the pH drops or the temperature rises above normal denaturing the protein
- 5. Protein Denaturation with extremepH or Temp.
- 6. Temp environ Temp cell Folded Proteins Unfolded Proteins Aggregates Loss ofProtein Function Network failure Death Cell
- 7. Interesting story F. Ritossa–1960 discovered the heat shock (HS) response while observing the salivary cells of Drosophila and named them HSP’s My name is Chaperone
- 8. How do Chaperoneswork? One major function of chaperones is to prevent both newly synthesised polypeptide chains and assembled subunits from aggregating into nonfunctional structures High temperatures and other stresses, such as altered pH and oxygen deprivation, make it more difficult for proteins to form their proper structures and cause some already structured proteins to unfold Heat Shock Proteins are induced rapidly at high levels to deal with this problem
- 9. Different Types ofHeat Shock Proteins Heat Shock Proteins are classified by their molecular weight, size, structure, and function. They are divided into several families, namely - 1. HSP100 2. HSP90 3. HSP70 4. HSP60 (chaperonin) 5. Small Heat Shock Proteins/ (alpha)-crystalline proteins
- 10. HSP100 Functions -solubilizes protein aggregatesthereby dissociating them -facilitates proteolysis -essential in yeast for acquired thermotolerance -essential for yeast prion propagation 6-7 monomer ATP no co-chaperon is required
- 12. HSP 90 stabilizes proteinsprior to complete folding or activation forms stable complexes with inactive glucocorticoid receptor and other transcription factors most abundant non-ribosomal protein (cytosolic version) most abundant protein in endoplasmic reticulum (ER version) dimer ATP HoP and p23
- 13. HSP90 interacts withHSP40, HSC70/HSP90 organizing protein (HOP), and co-chaperones to bind and stabilize newly synthesized substrate/client proteins. This ATPregulated cycle of substrate binding is critical to the activation of many oncogenic signaling molecules.
- 14. HSP70 monomer ATP DnaJ and GrpE assists in protein transport into mitochondria and the endoplasmic reticulum protects proteins under stress stabilizes proteins prior to complete folding transports across membranes and proteolysis
- 15. HSP70 works withHSP40 to capture and transfer misfolded client proteins to prefoldin and other chaperonins for refolding
- 16. HSP60 14-16 monomer ATP GroES and GroEL mediate the native folding of proteins through cooperation of HSP70 and 60
- 18. A) Reconstruction ofthe GroEL structure with and without the GroES ™lid∫ from cryoelectron microscopy pictures. B) Model of the GroEL chaperone cycle. Two misfolded proteins (green and blue) are simultaneously folded in a phase-shifted manner. The red circles symbolize the hydrophobic substrate binding sites of GroEL
- 19. sHsp 8-24 monomer exhibit chaperone activity in vitro and thermoprotection in vivo produced at significant levels in cells experiencing heat stress most are heat inducible, but some are synthesized in unstressed conditions-such as for cell development
- 20. Denatured or unfoldedsubstrates bind to the hydrophilic surface of small HSP complexes and prevent the substrate from aggregating.The substrate either stays sequestered or is released to be refolded or degraded.
- 21. Why Don't HeatShock Proteins Denature? Better Hydrogen Bonds Better Hydrophobic Internal Packing Enhanced Secondary Structure Helix Dipole Stabilization
- 22.