protein folding, heat shock proteins and disease involved with protein misfolding
DESCRIPTION
A complete understanding of protein folding, the role of Heat shock proteins and the ill effects of protein mis-foldingTRANSCRIPT
GOOD MRNING
GODO MRONING
GOOD MORNING
Proteins
Diversity of Proteins
HemoglobinHormonesEnzymesAntibodiesCollagen…………
If there is a job to be done in the molecular world of our cells, usually that job is done by a Protein
“ Proteins are the work horses of the cell”
Hence
How did the first protein originate?
Origin of Life
Iam the author of “History of Humanity”
Frederick BantingHugo TheorellEarl W SutherlandGerald M EdelmanRodney PorterRosalyn S YalowAlfred G Gilman Martin RodbellStanley PrusinerAaron CiechanoverAvram HershkoIrwin RoseWendell Meredith Stanley
Paul D BoyerJohn E WalkerAaron KlugJohn Warcup CornforthChristian B AnfinsenStanford MooreWilliam SteinMax Ferdinand PerutzJohn Cowdery KendrewFrederick SangerArne W K TiseliusJohn Howard Northrop
What is Protein folding ?
Structural Levels of ProteinsPrimary Secondary
Protein stability
The extreme diversity in their chemical and physical properties is achieved due to the variety in their properties of their building blocks Effort to design a protein with a specific function, nature has to solve an extremely difficult problem It needs be active and thermodynamically stable
Protein stability The situation becomes more complicated since this stability must be ascertained in a certain range of environmental conditions
The native conformation of a protein is stable in a narrow range of temperature,pH, chemical composition of solvent, etc.
ProteinpH Temp.
Salt Conc.
• Hydrogen Bonding
• Vander Waals interactions
• Ionic strengths
• Disulfide bonds
Hydrophobicity: the dominant
force in protein folding
Forces involved in Protein stabilisation
Protein Denaturation
The activity 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
Protein Denaturation with extreme pH or Temp.
Folding a protein on a computer with a full-atom
model in explicit solvent has been termed the
'holy grail' of the protein folding problem
Berendsen HJC:Science 1998, 282: 642)
A glimpse of the holy grail?
“The Quest for Holy Grail”
unfolding refolding
Anfinsen - Nobel Prize 1972
8M ureaDilution of denaturant
“ Ribonuclease ”
Break through…
Protein denaturation by temperature
R John Ellis Current Opinion in Structural Biology 2001, 11:114–119
Macromolecular crowding
Invitro refolding of a Protein
Native
UnfoldedProtein with 100 amino acid residues
Assume 2 conformations for each residue
2100 possibilities
1010 years of random searching
Levinthal paradox (1968)
Folding models:
Framework model Hydrophobic collapse mode Nucleation condensation model
Folding is a stepwise process
Local secondary structures forms first and this is Followed by longer range interactions
A stably folded proteins has…..
Hydrophobic side chains buried Charged side chains on the surface Cysteine’s form Covalent disulfide bonds
“All these features will contribute to Minimum” energy state
Pack as close together as possible Pack as close together as possible Minimize contacts between hydrophobic Minimize contacts between hydrophobic groups and watergroups and water
Free energy funnel
Native structure
Mutations Premature termination of Translation Fault in post-translational modifications Strong Promoters High Inducer concentrations
Reasons for protein misfolding
Loss of conformation due to stress`
ALL CELLS
ALL ORGANISMS
Living in the World
Must cope with…
Stress !!!
What is stress?
In biology, stress is the driving force behind the process of adaptation and evolution.
Driven by inner need and Stress
Interesting storyF. Ritossa –1960 discovered the heat shock (HS) response while observing the salivary cells of Drosophila and named them HSP’s
My name is Chaperone
Tempenviron
Tempcell
Folded Proteins
Unfolded Proteins Aggregates
Loss of ProteinFunction
Networkfailure
Death
Cell
How do Chaperones work? Heat shock proteins stabilize proteins and
are involved in the folding of denatured
proteins
Hsp 100
Hsp 90
Hsp 60
Hsp 70
SmallHsp’s
Hsp 40
Family Major Functions
Protein disaggregation, thermotolerance
Regulatory interactions with signaling proteins, stabilization of misfolded proteins
Protein folding, membrane transport of proteins
Protein folding (limited substrates in eukaryotic cytoplasm)
Protein folding, co-chaperone for Hsp70
Stabilization of misfolded proteins, thermotolerance,eye lens structural proteins
Functions of HSP families
Other inducers of the heat shock proteins:
Oxidizing agents
Metals
Sulfhydryl reagents
• Poisonous gases…………
The Nobel Prize Chemistry 2004
"Kiss of Death"
Aaron Ciechanover, Avram Hershko, Irwin Rose
Exit
Entry
Protein misfolding Diseases
Protein misfolding diseases can be classified in to two categories
Diseases caused due to the misfolding or degradation of misfolded proteins Diseases caused due to accumulation of misfolded proteins
Disease Protein Involved
Cystic Fibrosis CFTR
Retinitis pigmentosa Rhodopsin
Cancer p53
Osteogenesis imperfecta
Type 1 procollagen
Pro A
Marfan Syndrome Fibrillin
Sickle Cell anemia Hemoglobin
Disease caused due to the misfolding or degradation of misfolded Protein
Polymerized Sickle Hemoglobin
Sickle-cell anemia
Sickle shaped RBC
Retinitis Pigmentosa
Normal Vision
Retinitis Pigmentosa
Gene codes for a protein, CFTR, which is chloride ion channel. Small fraction of protein matures to the cell surface Mutation in protein CFTRΔF508 doesn't reach the cell surface.
Cystic fibrosis
Osteogenesis imperfecta
Disease Protein involved
Alzheimer’s Disease Amyloid - peptide
Huntington Disease Huntington protein
Spongiform encephalopathies
Prion Protein
Diseases caused due to the accumulation of misfolded protein
Prion infected Brain of a cattle
Bovine Spongiform Encephalopathy
Prion Protein
Prion diseases Human - Kuru & CJD
Sheep - Scrapie.
Cow - Mad Cow disease
KuruVictim
MadCow
“I Have Completely Forgotten Why I came Upstairs “
Alzheimer’s Disease
SummaryProper folding of proteins is essential for a cell to carry out Its normal cellular function
Misfolded proteins can result in a wide variety of pathological conditions
Existing therapies do not provide efficient cure for these Pathological conditions
Small molecules called chaperones that increase the stability of the native state offer innovative therapeutic solution
Why study protein folding?Understanding Protein folding in vivo helpsin adapting them in invitro and Insilco Molecular Drug design Protein-protein interactions Grastim Dengue vaccine
Mobile phones, heat shock proteins Mobile phones, heat shock proteins and cancerand cancer
Mobile phone use
Absorption of energy in to brain tissue
Protein unfolding
Heat shock response
Heat shock proteins induced HSP 27,40,70,90,110Repeated mobile use
Chronic expression of HSPs
Inductionof cancer
Increasedmetastasis
Inhibition of Apoptosis
Resistance to anti cancer drugs
Proteinrefoldin
g
Thank you
Supplementary