Download Heat shock Proteins (HSPs)

Heat shock Proteins (HSPs)
Heat shock proteins (HSP) are expressed in
response to various biological stresses,
including heat, high pressures, and toxic
compounds. It is also one of the most
abundant cellular proteins found under nonstress conditions
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Hsp90 is part of a family of proteins known
as "chaperones," which are solely dedicated
to helping other proteins fold and assume
their proper functions.
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The chaperones Hsp70 and Hsp90 together
with co-chaperones function to fold proteins in
the cytoplasm. Sometimes Hsp70 and Hsp90
function sequentially to fold the same protein
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Cells are vigilant about getting these folds
right because misfolded proteins can change
the normal life of the cell. In some cases
change is good, in others deadly.
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When HSP90 is compromised the number of
morphological changes increases, which lead
to formation of inactive or abnormally active
polypeptides.
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Domain structure of HSP90.
Mad Cows, People & yeast
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What do "mad cows," people with
neurodegenerative diseases and an
unusual type of yeast have in common?
They are all experiencing the effects of
misfolded proteins, according to HHMI
investigator Susan Lindquist of the
University of Chicago.
Her research identified a role for HSP90 in
the process of evolution.
They have reported that fruit flies that
make too little of the Hsp90 protein
develop dramatic deformities, such as an
extra antenna, additional bristles, notched
wings or malformed eyes.
The defects result from multiple hidden
variations in the genome.
When affected flies are interbred, these
factors are enriched and subsequent
generations have the same deformities,
even though they have normal levels of
Hsp90.
Source:http://www.hhmi.org/annual98/research/madcow.html
Susan Lindquist
University of Chicago
"My view is that
molecular chaperones
are a way of changing
the traits of an
organism that arose
very early in evolution.
They might be as old as
RNA and DNA."
HSPs in protein folding
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The diagram shows the role of heatshock proteins and a chaperonin in
protein folding. As the ribosome moves
along the molecule of messenger RNA,
a chain of amino acids is built up to
form a new protein molecule. The
chain is protected against unwanted
interactions with other cytoplasmic
molecules by heat-shock proteins and a
chaperonin molecule until it has
successfully completed its folding.
Source: (http://www.cs.stedwards.edu/chem/Chemistry/CHEM43/CHEM43/HSP/FUNCTION.HTML)
HSP90-alpha protein sequence
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HSP90alpha
732 aa
HSP90beta
724 aa
>HSP90alpha
MPEETQTQDQPMEEEEVETFAFQAEIAQLMSLIINTFYSNKEIFLRELISNSSDALDKIRYESLTDPSKLDSGKELHINLIPNKQDRTLTIVDTGIGMTKADLINNLGTIAKSGTKAFME
ALQAGADISMIGQFGVGFYSAYLVAEKVTVITKHNDDEQYAWESSAGGSFTVRTDTGEPMGRGTKVILHLKEDQTEYLEERRIKEIVKKHSQFIGYPITLFVEKERDKEVSDDEAE
EKEDKEEEKEKEEKESEDKPEIEDVGSDEEEEKKDGDKKKKKKIKEKYIDQEELNKTKPIWTRNPDDITNEEYGEFYKSLTNDWEDHLAVKHFSVEGQLEFRALLFVPRRAPFDL
FENRKKKNNIKLYVRRVFIMDNCEELIPEYLNFIRGVVDSEDLPLNISREMLQQSKILKVIRKNLVKKCLELFTELAEDKENYKKFYEQFSKNIKLGIHEDSQNRKKLSELLRYYTSAS
GDEMVSLKDYCTRMKENQKHIYYITGETKDQVANSAFVERLRKHGLEVIYMIEPIDEYCVQQLKEFEGKTLVSVTKEGLELPEDEEEKKKQEEKKTKFENLCKIMKDILEKKVEKV
VVSNRLVTSPCCIVTSTYGWTANMERIMKAQALRDNSTMGYMAAKKHLEINPDHSIIETLRQKAEADKNDKSVKDLVILLYETALLSSGFSLEDPQTHANRIYRMIKLGLGIDEDDP
TADDTSAAVTEEMPPLEGDDDTSRMEEVD
Green bases = Geldanamycin-Binding Domain
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Brown bases = Transmembrane segments as
predicted by Tmap.
Hydrophobic: A,C, I,L, M, F, V,P, Y,W
Hydrophilic: R,N, H,D, E,Q, K, S,T Either G
TMAP output
GREASE output
BLASTp
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With the HSP90 sequence in hand we used Blastp to find homologous sequences
We were surprised to find a lot of homologous sequences across many species like Humans,
Chicken,Pig, Mouse,Horse,Fish, Coral,fruit fly, mosquito, nematode,& even crops like rice,
maize & tobacco.
The first 100 matches had e-values ranging from 0 to e-153, so they were *very* strong
matches indicating a high degree of conservation of the protein through evolution.
ID
Name
304882
heat shock 90kDa protein 1, alpha [Homo sapiens] N...
Score
Evalue
1247
0.0
352285
heat shock protein 1, alpha [Mus musculus] NP_0346...
825
0.0
761972
heat shock protein 86 [Rattus norvegicus] NP_78693...
825
0.0
341493
heat shock protein 90A [Cricetulus griseus] AAA369...
817
0.0
609431
heat shock protein 90 - chicken
816
0.0
609432
heat shock protein 84 - mouse
745
0.0
449511
(Q9W6K6) Heat shock protein hsp90 beta [Salmo sala...
731
0.0
459017
heat shock protein hsp90 [Oncorhynchus tshawytscha...
730
0.0
446434
heat shock protein hsp90beta [Danio rerio] AAC2156...
729
0.0
361999
heat shock protein 90 [Rattus sp.] AAB23369.1 [S45...
724
0.0
460597
heat shock protein 90 [Pleurodeles waltl] AAA92343...
719
0.0
738604
90-kDa heat shock protein [Bombyx mori] BAB41209.1...
712
0.0
146263
Heat shock protein 83 CG1242-PA [Drosophila melano...
669
0.0
755572
heat shock protein 90 [Dendronephthya klunzingeri]...
662
0.0
226533
(P33126) Heat shock protein 82 [Oryza sativa (Rice)]
612
e-174
1888761
heat shock protein 82 - common tobacco (fragment)
612
e-174
252633
heat shock protein [Arabidopsis thaliana] CAA72513...
600
e-170
236351
(Q9XGF1) HSP80-2 [Triticum aestivum (Wheat)]
598
e-169
283559
(Q08277) Heat shock protein 82 [Zea mays (Maize)]
593
e-168
152674
heat shock protein 86 [Plasmodium falciparum] AAA6...
591
e-167
1899880
(Q8LLI6) Heat shock protein Hsp90 [Achlya ambisex...
579
e-164
245912
heat shock protein 90 [Lycopersicon esculentum] AA...
544
e-153
Multiple sequence alignment
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Multiple
sequence
alignments
were done
using ClustalW
using different
species & the
following
unrooted
phylogenetic
tree was
generated.
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Rooted
phylogenetic
tree.
Structure analysis
We found ‘open’ and
‘closed’ conformations for
the GeldanamycinBinding Domain of the
Human Hsp90 protein &
decided to study their
differences. The parts in
yellow are the selected
residues which are also
the transmembrane
segments. The residues
‘gtia’ in the sequence
viewer show where the
structures differ. The
same region is depicted
as the little grey segment
at one end of the
transmembrane
segments
Comparison between Open & Closed conformations of human
HSP90 alpha
Transmembrane segments in yellow
Comparison of HSP90 structures in Yeast & Human
We compared the HSP90 structures in yeast & human & found that the protein structures were very similar. The
picture below shows the 2 structures superimposed with the highlighted portion showing an additional residue in the
yeast sequence.
Structures compared:
1YES Human Hsp90 Geldanamycin-Binding Domain, "open" Conformation [mmdbId:7483]
1AMW : Atp Binding Site In The Hsp90 Molecular Chaperone,Saccharomyces cerevisiae (yeast) [mmdbId:7950]
Red : identical residues
Blue : similar residues
Yellow: selected residues
Microarray Data
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We found microarray data on the Cancer Genome Anatomy Project web site
http://cgap.nci.nih.gov/Genes/GeneFinder
HSP90-alpha
This screen shot
shows the
microarray data for
HSP90 alpha
expression in
various types of
cancers.
HSP90-beta
This screen shot
shows the
microarray data for
HSP90 beta
expression in various
types of cancers.
Current Studies on HSP90
Changes in protein conformation are involved in some of the most devastating and
intractable diseases.
“Studies in yeast may help us decipher the fundamental nature of these disorders,
including Creutzfeldt-Jakob, Alzheimer’s, Huntington’s, and Parkinson’s
disease in humans and mad cow disease in cattle. Several of the protein culprits
are being imported into yeast, which allows for the manipulation & study of their
folding transitions & testing of therapeutic strategies.
(http://www.wi.mit.edu/nap/pdfs/Directors_Report/dir_lindquist02.pdf)
Conclusion:
HSP90 is a powerful evolutionary mechanism that ensures apparent genetic
stability at physiological conditions and at the same time allows the mutations that
could rapidly become manifest under stress.
References:
http://www.stanford.edu/class/gene211/hsp90_search
http://www.chemie.tu-muenchen.de/biotech/en/hsp90-e.html
http://www.hhmi.org/annual98/research/madcow.html
www.ashland.edu/~kstine/Research/Stress%20proteins.pdf