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This was the report in Medical Biochemistry.
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MOLECULAR CHAPERONES
Group 5 – A2Capacio, Diane Chloe
Cardeño, Sheree Ann Rachille
Casem, Princess Joy
Casteñeda, Felix II
Castro, John Michael
Ceneta, Raymond
INTRODUCTIONChaperones Proteins which assist in protein folding Assists in the translocation of polypeptide
chains Multiprotein assembly and disassembly Escort some proteins to specific
destinations Rescue proteins trapped in misfolded
dead-ends (folded in their hydrophobic regions)
During the synthesis of proteins, parts of it already begin folding
The instruction on the sequence’s proper folding is dependent on the amino acid sequence itself
Protein folding
Protein folding
Most of the hydrophobic amino acids are buried inside the structure (core)
Some proteins already fold as it comes out of the ribosome in a matter of seconds, forming what is called a molten globule
Chaperones assist in folding of some proteins
Chaperones assist in folding of some proteins
They are of much help since there are a number of pathways at which the protein can achieve its final form from an unfolded state
Many of these chaperones are termed heat shock proteins because they are made in abundance at an elevated temperature (~42oC for cells normally at 37oC)
Chaperones assist in folding of some proteins
A feedback-like system is made in this setting, since an increase in unfolded proteins resulting from an increased temperature will eventually lead to the synthesis of chaperones
Chaperones assist in folding of some proteins
Some of the major chaperone families include Hsp60 and Hsp70, which functions at different organelles
The mitochondria have its own set of Hsp60 and Hsp70 proteins which are distinct from those found in the cytosol and BIPs (special types of Hsp70) in the endoplasmic reticulum
Chaperones assist in folding of some proteins Hsp70s act early in the synthesis of the
protein before that protein leave the ribosome
Hsp60s, however, acts on the fully synthesized protein by forming a barrel-like structure. Hsp60s are also termed as “Chaperonin” and they have what is called an “isolation chamber” where the misfolded protein is fed into
Chaperones assist in folding of some proteins
Chaperones use a series of ATP hydrolysis in aiding a protein to fold correctly
How does the cell recognize misfolded proteins?
Usually, when a hydrophobic region is at the protein globule surface, it is considered abnormal
Presence of these kinds of proteins may render, not only nothing for the cell, but also danger. Aggregations of misfolded proteins may result to some known severe human diseases
Types of Molecular Chaperones
Folding Holding Those that increase solubility of proteins
Role in protein assembly
They guide in the proper folding of proteins
Misfolded proteins are allowed to refold into their correct conformation by having a suitable environment which is provided by the chaperones, chaperonins in particular
Refolding of denatured proteins
In a study involving recombinant HSP17 of Synechocystis sp., malate dehydrogenase which underwent denaturation made complexes with HSP17 which then functioned as a storage of the unfolded protein, and later on transported to the network of Dnak/DnaJ/GrpE and GroEL/ES chaperones for eventual refolding (Török etal., 2001)
Production of recombinant proteins
In a study using E. coli, overproduction of bacterial chaperones, GroEL and GroES, via genetic engineering resulted to high yield of recombinant human protein-tyrosine kinase p50csk which are in an insoluble forms within the bacterial cell.
Production of recombinant proteins
Overproduction of these chaperones resulted in the subsequent dissolution of the protein kinase and enabled its purification (Amrein et al., 1995)
Production of cancer vaccines HSPs which are derived from a
particular tumor has been known to bring on immunity against the tumor where came from that tumor. Vaccines of this kind are effective on different types of tumors and can bypass the need for identifying the responsible peptide which causes the immunity
Production of cancer vaccines
These vaccines are specific for the tumor and for the patient because they confine the identity of the tumor cell. HSP96 has already been studied with a number of cancer illnesses such as, melanoma, renal cell carcinoma, gastric cancer, pancreatic cancer, low-grade lymphoma, colorectal cancer and chronic myelogenous leukemia (Oki and Younes, 2004)
Possible causes of Protein Misfolding
•Genetic Mutation•Increased Heat Production
Properties of Chaperones
•Present in a wide range of species from bacteria to humans•Many are so called Heat Shock Proteins•Some are inducible by conditions that cause unfolding of newly synthesized proteins
•They bind to predominantly hydrophobic regions of unfolded proteins and prevent their aggregation•They act in part as quality control•Associated with ATPase activity•Found in cytosol, mitochondria and lumen of ER
Activation of Chaperones
Rely on ATP-driven conformational change
Most of the hydrophobic amino acids are buried inside the structure (core)
Holding Chaperones Maintains partially folded protein
on their surface to await availability of folding chaperone upon stress abatement
Chaperons w/c Promotes Solubility of Protein
Aggregates as a result of stress
2 Major Types of Molecular Chaperones Hsp 6O
Also called Chaperonin
Barrel like structure- where unfolded
protein is retained, giving it time &
suitable env’t to fold properly
Hsp 7O
These protein acts early, recognizing small strech of hydrophobic amino acid pn a protein surface
GroEL-GroES System
It is a bacterial chaperone belong to Hsp 6O family
It is a hollow cylinder consist of 2 seven subunit rings stacked back to back
Dnak Chaperones
They are chaperones of host protein, refolding, translocation and general mngt of deleterious effest of stress
They are under the hsp70 family
Hsp33
Also know as REDOX-ACTIVATED HOLDING CHAPERONES
It is a redox regulated chaperon that stabilized protein unofolded by severe oxidative stress
Hsp31
Also known as Managing Heat & AcidStress
It fxn as a holding chaperons that helps cell handle protein unfolding under extremes of temp.
Plays role in ability of strved E. Coli to survive in a acid stress
Clp Disaggregase
Belong to hsp100 family w/c role is to degrade unfolded/misfolded protein or to stabilized and reactivate aggregate proteins
PROSPECTIVE THERAPEUTIC RATIONALES THAT INVOLVE
CHAPERONES
Drugs targeting specific Chaperone Activities
1. Immunophilinsa. Immunosuppressants cyclosporin A
and FK506• Transplantation procedure,
autoimmune and inflammatory diseases.
• Useful as neurotrophic agents.
2. HSP70a. DSG interact selectively with HSP70
class chaperones• Potent immunosuppressive agent.• Maybe able to reverse renal
allograft rejection episodes.• Maybe quite useful in combination-
therapy.• Further studies required.
3. HSP90• Inhibitors of signal transduction • Examples are GA and
benzoquinone ansamycins which are potential as anti cancer agents
Induction of protein and chemical chaperones
Injury protection
•Induction of heat shock response might be an effective prophylactic treatment to minimize myocardial injury.
•Herbimycin which induce activation of HSF1 has been shown to protect cardiomyocytes in culture.
ReferencesCampbell, NA, JB Reece, LA Urry, ML Cain, SA Wasserman, PV Minorsky and RB
Jackson. 2008. Biology 8th ed. Pearson Benjamin Cummings, CA
Alberts, B, A johnson, J Lewis, M Raff, K Roberts and P Walter. 2008. Molecular Biology of the Cell 5th ed. Garland Science, UK
Amrein, KE, B Takacs, M Steiger, J Molnos and P Burn. 1995. Purification and characterization of recombinant human p50csk protein-tyrosine from an Escherichia coli expression system overproducing the bacterial chapreones GroES and GroEL. Proc. Nat. Acad. Sci. 92(4):1048-1052.
Török, Z, P Goloubinoff, I Horvath, NM Tsvetkova, A Glatz, G Balogh, V Varvasovszki, DA los, E Veirling, JH Crowe and L Vigh. 2001. Synechocystis HSP17 is an amphitropic protein that stabilize heat-stressed membranes and binds denatured proteins for subsequent chaperone-mediated refolding. Proc. Nat. Acad. Sci. 98(6):3098-3103.
Oki, Y and A Younes. 2004. Heat shock protein-based cancer vaccines. Expert Review of Vaccines 3(4):403-411.
http://faculty.washington.edu/baneyx/Chaperones/Chaperones.html
Smith, D, L Whitesell and E Katsanis. 1999. Molecular Chaperones: Biology and Prospects for Pharmacological Intervention. Pharmacological Reviews 50(4): 493-514.