Biophysical analysis of the effect of chemical modification by 4-oxononenal on the structure, stability, and function of binding immunoglobulin protein (BiP)

Abstract

Binding immunoglobulin protein (BiP) is a molecular chaperone important for the folding of numerous proteins, which include millions of immunoglobulins in human body. It also plays a key role in the unfolded protein response (UPR) in the endoplasmic reticulum. Free radical generation is a common phenomenon that occurs in cells under healthy as well as under stress conditions such as ageing, inflammation, alcohol consumption, and smoking. These free radicals attack the cell membranes and generate highly reactive lipid peroxidation products such as 4-oxononenal (4-ONE). BiP is a key protein that is modified by 4-ONE. In this study, we probed how such chemical modification affects the biophysical properties of BiP. Upon modification, BiP shows significant tertiary structural changes with no changes in its secondary structure. The protein loses its thermodynamic stability, particularly, that of the nucleotide binding domain (NBD) where ATP binds. In terms of function, the modified BiP completely loses its ATPase activity with decreased ATP binding affinity. However, modified BiP retains its immunoglobulin binding function and its chaperone activity of suppressing non-specific protein aggregation. These results indicate that 4-ONE modification can significantly affect the structure-function of key proteins such as BiP involved in cellular pathways, and provide a molecular basis for how chemical modifications can result in the failure of quality control mechanisms inside the cell.

Salidroside inhibits the proliferation and migration of gastric carcinoma cells and tumor growthviathe activation of ERS-dependent autophagy and apoptosis

“…It is now widely accepted that ER stress is the most potent trigger for the autophagy of many tumor cell types. 34 As illustrated above, the activation of ER stress in gastric cancer cells was caused by the treatment with Salid. In this case, a mechanism of ERS-dependent autophagy activation might have evolved in the process of Salid-induced gastric cancer inhibition.…”

“… 33 In addition, GRP78/BiP has a cytoprotective effect in oncogenesis, and the overexpression of BiP has been reported to be closely related to the drug resistance of cancer. 34 SOD represents an important enzyme that has protective effects on cancer cells against apoptosis resulting from oxidative stress, while the MDA content is always used as the definitive marker of lipid peroxidation. 35 Taking these factors in consideration, an examination of the levels of CHOP, cleaved caspase-12, GADD34, BiP, SOD, and MDA was used for the evaluation of Salid-induced ER stress in this work.…”

Caracterização estrutural, funcional e estabilidade térmica das proteínas humanas HspA5 e HspA8: uma abordagem comparativa

“…A HspA5, também conhecida como BiP (do inglês Binding immunoglobulin protein) ou Grp78 (do inglês 78-kDa glucose regulated protein), é uma proteína pertencente à família das Hsp70 humanas, sendo o membro mais abundante da família Hsp70 (CASAS, 2017;SHAH et al, 2017 LEE, 2018); participa ativamente da resposta ao estresse celular (BOOTH et al, 2015;DEDIEGO et al, 2011); regula a resposta a proteínas não enoveladas (UPR, do inglês unfolded protein response) (SUN et al, 2006;TSAI;LEE, 2018;WANG et al, 2009); entre outras funções (BAILLY;WARING, 2019;CHIARANTE et al, 2018;GE, 2019…”

“…Com o objetivo de comparar as proteínas humanas HspA5 e HspA8 quanto a sua estabilidade, ensaios de desenovelamento químico e térmico foram realizados. KIRALY et al, 2020;SHAH et al, 2017). 1,6 ± 0,1 3,1 ± 0,1 1,6 ± 0,1 3,1 ± 0,1 HspA8 1,8 ± 0,3 2,7 ± 0,3 1,5 ± 0,1 3,6 ± 0,1 * Ensaios realizados utilizando o agente caotrópico ureia (0 -8 M).…”

“…A proteína HspA5 quando submetida à desnaturação térmica monitorada por DSC apresentou duas Tms, 51,6 ± 0,4 ºC e 70,8 ± 0,3 ºC, em um processo de desnaturação irreversível (dados não mostrados). De maneira similar, a proteína HspA8 também apresentou irreversibilidade no processo de desnaturação monitorado por DSC (dados não mostrados) e duas Tm bastante evidentes, 50,5 ± 0,2 ºC e 66,1 ± 0,4 ºC, o que também foi observado para outras Hsp70 (KIRALY et al, 2020;LAMB et al, 2006;SHAH et al, 2017).…”