The 73 kilodalton heat shock cognate protein purified from rat brain contains nonesterified palmitic and stearic acids

Abstract

A protein related to the 71 kilodalton inducible rat heat shock protein was purified to electrophoretic homogeneity in milligram amounts from brain tissue of nonheat-stressed rats. The protein has been designated as a stress cognate protein based on previous studies and data presented herein that this protein cross-reacted with a monoclonal antibody originally raised against the Drosophila 70 kilodalton heat shock protein. The purified protein had an apparent molecular mass of 73 kilodaltons when analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and an apparent mass of 150 kilodaltons as determined by nondissociative gel chromatography, suggesting that the purified protein is a homodimer. The purified protein had isoelectric points of 5.0 under nondissociative conditions and 5.6 when exposed to protein denaturants, suggesting loss of bound anionic molecules and/or net exposure of basic residues upon denaturation. Chloroform/methanol extraction of the purified protein and subsequent analyses by thin layer and gas-liquid chromatography resulted in the identification of palmitic and stearic acids noncovalently bound to the protein. Approximately four molecules of fatty acids were bound per dimer with palmitic and stearic acids present in a one-to-one ratio. The purified protein did not bind exogenously added radioactive palmitate, indicating that the fatty acid-binding sites of the cognate protein were fully occupied and that the associated fatty acids were too tightly bound to exchange readily. The possible significance of the fatty acids associated with the 73 kilodalton stress cognate protein is discussed.

Salivary histatin 3 inhibits heat shock cognate protein 70-mediated inflammatory cytokine production through toll-like receptors in human gingival fibroblasts

“…Furthermore, the levels of inflammatory cytokine production after treatment with heated HSC70 were very low (Figure 4). In addition, histatin 3 significantly inhibited NF-κB activation and inflammatory cytokine production caused by HSC70 stimulation (Figures 2B and 6), although HSPs possess an affinity for lipids [43,44]. It is also difficult to precisely quantify the small amount of HSC70 associated with lipids in the HSC70 reagents.…”

Staphylococcus aureusDeficient in Lipidation of Prelipoproteins Is Attenuated in Growth and Immune Activation

“…3A and B). They are possibly associated with the lipid moiety of the lipoproteins and in this way become exposed to the outer surface, since many prokaryotic and eukaryotic heat shock proteins have been shown to interact noncovalently with lipids and fatty acids (2,10,21).…”

Arachidonate is a potent modulator of human heat shock gene transcription.

“…An alternative explanation for arachidonate's action is that it affects HSF1 directly or influences HSF1-DNA binding indirectly through its effects on Hsc/ Hsp7O proteins (47,48). Other free fatty acids, including palmitic and stearic acid, have been shown to associate with Hsc7O (49,50), thus offering an additional link between fatty acids and their potential regulatory role during the heat shock response.…”