Dilna J.P asked:
HEAT SHOCK PROTEINS -
“ THE GRAND PERCEPTION “
Heat shock proteins:
Heat shock proteins (Hsps) comprise a group of ubiquitous polypeptides whose expression is induced when cells are subjected to stressful conditions such as – increasing temperature, high pressure, or toxic compounds. The induction of Hsp correlates with the abundance of unfold polypeptide chains, which suggest a protective physiological role of the proteins.
Important role of Hsps:
The Hsp functions as a Chaperone by either facilitating the protein back to its proper confirmation or if the damage is irreparable,then the protein is targeted for destruction. Hsp involved in the assembly and disassembly of multimeric protein structures, the translocation of proteins across membranes, and the secretion & degradation of proteins. The use of cognate heat shock protein 70 – peptide complex to elicite an immune response against cancer and viral, bacterial and other infectious agents.
Heat shock proteins don’t get denature, because of their;
Better hydrogen bonds Better hydrophobic internal packing. Enhanced secondary structure. Helix dipole stabilization.
Based on molecular weight, size, structure and function, the Hsp’s are classified as…. Hsp100; Hsp90; Hsp70; Hsp60 (Chaperonin); Hsp 27; etc.
The molecular evolution of the small heat-shock proteins in plants:-
The small Hsp have undergone a tremendous diversification in plants; whereas only a single small Hsp is found in fungi and many animals, over 20 different small Hsp’s are found in higher plants. The small Hsp in plants have diversified in both sequence & cellular localization and are encoded by at least five gene families. Recent studies shows,there are 44 small Hsp DNA and amino acid sequences were examined,using both phylogenetic analysis and analysis of nucleotide substitution patterns to elucidate the evolutionary history of the small Hsp’s. The phylogenetic relationships of the small Hsp’s, estimated using parsimony and distance methods,reveal that gene duplication,sequence divergence and gene conversion have all played a role in the evolution of the small Hsp’s. This suggests that the small Hsp’s may have diversified in function as well as in sequence & cellular localization.
The small Hsp’s are smaller than 30KDa in size. Higher plants have at least 20 and some plant species may have as many as 40 different small Hsp’s. In contrast, most other organisms have one or only a few small heat shock proteins. Saccharomyces cerevisiae has 1 small Hsp and Drosophila has four.
Heat shock proteins of higher plants:-
The pattern of protein synthesis changes rapidly and dramatically when the growth temperature of soybean seedling tissue is increased from 28 degree Celsius(normal) to about 40 degree Celsius(heat shock).The synthesis of normal proteins is greatly decreased and a new set of proteins, “heat shock proteins” is induced.The Hsp of soybean consists of 10 new bands on one-dimensional NaDodSo4 gels; a more complex pattern is observed on two-dimensional gels. When the tissues is returned to 28 degree Celsius after 4 hr at 40 degree Celsius, there is progressive decline in the synthesis of Hsp’s and reappearence of a normal pattern of synthesis by 3 or 4 hr. The heat shock response in soybean appears similar to the much studied heat shock phenomenon in Drosophila.
Expression of low molecular weight Heat shock proteins under field conditions :-
Hsp’s are known to be expressed in plants experiencing high temperature stress. The study has been done on class I cytoplasmic low molecular weight (LMW) Hsp’s and found that the Hsp’s als frequently accumulate in seeds, seed pods and flowers during a normal growing season. The expression of class I cytoplasmic LMWHsp’s were examined by western blot analysis in a range of seed samples from both commercially growm and wild legumes. LMWHsp’s were present in all seed samples, indicating that the Hsp’s are regularly expressed in the tissues. Parallel greenhouse studies indicate that Hsp expression in seeds is in part developmentally regulated. In total,data suggest a more widespread occurence of Hsp’s in optimal growth environments and emphasize their potential role during reproduction.
Commonly used antibiotics induce expression of Hsp 27 and Hsp 60 and protect human lymphocytes from apoptosis:-
Hsp’s are abundant molecular chaperones participating in the cytoprotection. The kinetics of synthesis of Hsp’s closely correlates with the kinetics of development of resistance to cell death. The probable involvement of Hsp27 and Hsp60 in the protection of cells undergoing apoptosis. Human lymphocytes cultured in the presence of ampicillin or ceftriaxone produced Hsp60 and Hsp27, estimated by immunoblotting in a time-dependent manner and the increased levels of Hsp60 and Hsp27 correlated with enhanced resistance of the lymphocytes to apoptosis, as determined by flow cytometry. Cultures treated with ampicillin or ceftriaxone also exhibited smaller number’s of apoptotic cells than untreated cultures when exposed to apoptosis- inducing agent staurosporine(1mM). In contrast,cloramphenicol induced the production of only small amounts of Hsp60, and no resistance apoptosis.
References:-
PNAS, vol.78 by Joe.L.Key, C.Y.Lin, and Y.M.Chen – June 1981.
Small Heat Shock Proteins and stress Transduction by Neininger.A.etal – Aug 1998.
Patent Storm – Aug 2003.
Science Direct by C.Carratelli Romano, N.Benedetto – Aug 2004.
Science Daily by Elisabeth Elsl – June 2006.
Plant Physiology by L.D.Hernandez and E.Vierling.
Med’s blog
HEAT SHOCK PROTEINS -
“ THE GRAND PERCEPTION “
Heat shock proteins:
Heat shock proteins (Hsps) comprise a group of ubiquitous polypeptides whose expression is induced when cells are subjected to stressful conditions such as – increasing temperature, high pressure, or toxic compounds. The induction of Hsp correlates with the abundance of unfold polypeptide chains, which suggest a protective physiological role of the proteins.
Important role of Hsps:
The Hsp functions as a Chaperone by either facilitating the protein back to its proper confirmation or if the damage is irreparable,then the protein is targeted for destruction. Hsp involved in the assembly and disassembly of multimeric protein structures, the translocation of proteins across membranes, and the secretion & degradation of proteins. The use of cognate heat shock protein 70 – peptide complex to elicite an immune response against cancer and viral, bacterial and other infectious agents.
Heat shock proteins don’t get denature, because of their;
Better hydrogen bonds Better hydrophobic internal packing. Enhanced secondary structure. Helix dipole stabilization.
Based on molecular weight, size, structure and function, the Hsp’s are classified as…. Hsp100; Hsp90; Hsp70; Hsp60 (Chaperonin); Hsp 27; etc.
The molecular evolution of the small heat-shock proteins in plants:-
The small Hsp have undergone a tremendous diversification in plants; whereas only a single small Hsp is found in fungi and many animals, over 20 different small Hsp’s are found in higher plants. The small Hsp in plants have diversified in both sequence & cellular localization and are encoded by at least five gene families. Recent studies shows,there are 44 small Hsp DNA and amino acid sequences were examined,using both phylogenetic analysis and analysis of nucleotide substitution patterns to elucidate the evolutionary history of the small Hsp’s. The phylogenetic relationships of the small Hsp’s, estimated using parsimony and distance methods,reveal that gene duplication,sequence divergence and gene conversion have all played a role in the evolution of the small Hsp’s. This suggests that the small Hsp’s may have diversified in function as well as in sequence & cellular localization.
The small Hsp’s are smaller than 30KDa in size. Higher plants have at least 20 and some plant species may have as many as 40 different small Hsp’s. In contrast, most other organisms have one or only a few small heat shock proteins. Saccharomyces cerevisiae has 1 small Hsp and Drosophila has four.
Heat shock proteins of higher plants:-
The pattern of protein synthesis changes rapidly and dramatically when the growth temperature of soybean seedling tissue is increased from 28 degree Celsius(normal) to about 40 degree Celsius(heat shock).The synthesis of normal proteins is greatly decreased and a new set of proteins, “heat shock proteins” is induced.The Hsp of soybean consists of 10 new bands on one-dimensional NaDodSo4 gels; a more complex pattern is observed on two-dimensional gels. When the tissues is returned to 28 degree Celsius after 4 hr at 40 degree Celsius, there is progressive decline in the synthesis of Hsp’s and reappearence of a normal pattern of synthesis by 3 or 4 hr. The heat shock response in soybean appears similar to the much studied heat shock phenomenon in Drosophila.
Expression of low molecular weight Heat shock proteins under field conditions :-
Hsp’s are known to be expressed in plants experiencing high temperature stress. The study has been done on class I cytoplasmic low molecular weight (LMW) Hsp’s and found that the Hsp’s als frequently accumulate in seeds, seed pods and flowers during a normal growing season. The expression of class I cytoplasmic LMWHsp’s were examined by western blot analysis in a range of seed samples from both commercially growm and wild legumes. LMWHsp’s were present in all seed samples, indicating that the Hsp’s are regularly expressed in the tissues. Parallel greenhouse studies indicate that Hsp expression in seeds is in part developmentally regulated. In total,data suggest a more widespread occurence of Hsp’s in optimal growth environments and emphasize their potential role during reproduction.
Commonly used antibiotics induce expression of Hsp 27 and Hsp 60 and protect human lymphocytes from apoptosis:-
Hsp’s are abundant molecular chaperones participating in the cytoprotection. The kinetics of synthesis of Hsp’s closely correlates with the kinetics of development of resistance to cell death. The probable involvement of Hsp27 and Hsp60 in the protection of cells undergoing apoptosis. Human lymphocytes cultured in the presence of ampicillin or ceftriaxone produced Hsp60 and Hsp27, estimated by immunoblotting in a time-dependent manner and the increased levels of Hsp60 and Hsp27 correlated with enhanced resistance of the lymphocytes to apoptosis, as determined by flow cytometry. Cultures treated with ampicillin or ceftriaxone also exhibited smaller number’s of apoptotic cells than untreated cultures when exposed to apoptosis- inducing agent staurosporine(1mM). In contrast,cloramphenicol induced the production of only small amounts of Hsp60, and no resistance apoptosis.
References:-
PNAS, vol.78 by Joe.L.Key, C.Y.Lin, and Y.M.Chen – June 1981.
Small Heat Shock Proteins and stress Transduction by Neininger.A.etal – Aug 1998.
Patent Storm – Aug 2003.
Science Direct by C.Carratelli Romano, N.Benedetto – Aug 2004.
Science Daily by Elisabeth Elsl – June 2006.
Plant Physiology by L.D.Hernandez and E.Vierling.
Med’s blog