Protein folding, and Heat Shock Proteins (HSPs)

[Guest guest]

Heat Shock Proteins are produced in response to thermal and

deprivation stresses. Protein synthesis during starvation seems to be

essential for protection of the organism.

It is possible that caloric restriction stimulates the production of

HSPs to keep our molecular machinery from degrading.

Tony

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Protein Folding - Edinburgh University

http://www.portfolio.mvm.ed.ac.uk/studentwebs/session2/group5/introliz.htm

This web site describes the current theory of how proteins fold. The

chapter on " Molecular Chaperones " describes Heat Shock proteins

(Hsp's), so called because they are produced when the cells are

subjected to elevated temperatures or other stresses such as glucose

starvation. It is theorized that the increase in Hsp's (which aid

protein refolding) could be a mechanism by which cells try to rectify

the increase in misfolded proteins (brought about by the elevated

temperature.

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http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=211389 & tools=bot

D E , J E Schultz, and A Matin

Starvation-induced cross protection against heat or H2O2 challenge in

Escherichia coli.

J Bacteriol. 1988 September; 170(9): 3910–3914.

Glucose- or nitrogen-starved cultures of Escherichia coli exhibited

enhanced resistance to heat (57 degrees C) or H2O2 (15 mM) challenge,

compared with their exponentially growing counterparts. The degree of

resistance increased with the time for which the cells were starved

prior to the challenge, with 4 h of starvation providing the maximal

protection. Protein synthesis during starvation was essential for

these cross protections, since chloramphenicol addition at the onset

of starvation prevented the development of thermal or oxidative

resistance. Starved cultures also demonstrated stronger thermal and

oxidative resistance than did growing cultures adapted to heat, H2O2,

or ethanol prior to the heat or H2O2 challenge.