Wheat protein disulfide isomerase improves bread properties via different mechanisms

Liang

et al. 2020

Molecules

Self Cite

Disulfide bonds play a pivotal role in maintaining the natural structures of proteins to ensure their performance of normal biological functions. Moreover, biological molecular assembly, such as the gluten network, is also largely dependent on the intermolecular crosslinking via disulfide bonds. In eukaryotes, the formation and rearrangement of most intra- and intermolecular disulfide bonds in the endoplasmic reticulum (ER) are mediated by protein disulfide isomerases (PDIs), which consist of multiple thioredoxin-like domains. These domains assist correct folding of proteins, as well as effectively prevent the aggregation of misfolded ones. Protein misfolding often leads to the formation of pathological protein aggregations that cause many diseases. On the other hand, glutenin aggregation and subsequent crosslinking are required for the formation of a rheologically dominating gluten network. Herein, the mechanism of PDI-regulated disulfide bond formation is important for understanding not only protein folding and associated diseases, but also the formation of functional biomolecular assembly. This review systematically illustrated the process of human protein disulfide isomerase (hPDI) mediated disulfide bond formation and complemented this with the current mechanism of wheat protein disulfide isomerase (wPDI) catalyzed formation of gluten networks.

Section: Proposed Catalytic Mechanism Of Wpdimentioning

confidence: 92%

“…[34,35,113]. In this section, we will discuss wPDI and the proposed catalytic mechanism with glutenin in dough [52,114].…”

Section: Formation Of Gluten Network Catalyzed By Wpdimentioning

confidence: 99%

PDI-Regulated Disulfide Bond Formation in Protein Folding and Biomolecular Assembly

Liang

et al. 2020

Molecules

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“…Among wheat proteins, 85–90% is gluten, and intolerance to it leads to an autoimmune disease called celiac sprue ( 4 ). Gluten includes glutenins and gliadins, and glutenins are catalyzed by related enzymes and/or oxidants to form a cohesive network as the structural basis of dough ( 5 ). Besides gluten from wheat, similar prolamin proteins such as hordeins from rye and secalins from barley could also trigger this inflammation ( 6 ).…”

Section: Introductionmentioning

confidence: 99%

Thermal and Acidic Treatments of Gluten Epitopes Affect Their Recognition by HLA-DQ2 in silico

Zhou

et al. 2021

Front. Nutr.

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Celiac disease (CD) is a prevalent disorder with autoimmune features. Dietary exposure of wheat gluten (including gliadins and glutenins) to the small intestine activates the gluten-reactive CD4+ T cells and controls the disease development. While the human leukocyte antigen (HLA) is the single most important genetic factor of this polygenic disorder, HLA-DQ2 recognition of gluten is the major biological step among patients with CD. Gluten epitopes are often rich in Pro and share similar primary sequences. Here, we simulated the solution structures changes of a variety of gluten epitopes under different pH and temperatures, to mimic the fermentation and baking/cooking processes. Based on the crystal structure of HLA-DQ2, binding of differently processed gluten epitopes to DQ2 was studied in silico. This study revealed that heating and pH change during the fermentation process impact the solution structure of gluten epitope. However, binding of differently treated gluten epitope peptide (GEP) to HLA-DQ2 mainly depended on its primary amino acid sequence, especially acidic amino acid residues that play a pivotal role in their recognition by HLA-DQ2.

“…Additionally, PDI also exhibits another important function—a molecular chaperone, which promotes the folding of nascent or denatured proteins and restores their natural activities [ 25 ]. Many studies have shown that the addition of PDI effectively improves the alveographic properties of dough, mainly by catalyzing the formation of rheologically active disulfide bonds [ 26 , 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

“…Currently, the mechanism of wPDI facilitated gluten network formation is limited to its catalyzed disulfide crosslinking in the N- and C-terminal domains of glutenin [ 27 ]. Neither the structure of wPDI nor how it interacts with the repetitive domain, which accounts for a larger proportion in glutenin, has been reported.…”

Section: Introductionmentioning

confidence: 99%

The wPDI Redox Cycle Coupled Conformational Change of the Repetitive Domain of the HMW-GS 1Dx5—A Computational Study

Liang

et al. 2020

Molecules

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The repetitive sequence of glutenin plays an important role in dough rheology; however, its interaction with wheat protein disulfide isomerase (wPDI) remains unclear. In this study, the conformations of wild type glutenin repetitive sequence (WRS) from the high molecular weight glutenin subunit (HMW-GS) 1Dx5, an artificially designed glutenin repetitive sequence (DRS) of which the amino acid composition is the same but the primary structure is different, and wPDI under different redox states were simulated. The molecular interactions between the aforementioned repetitive sequences with wPDI under different redox states were further investigated. The results indicated that the repetitive sequences bind to the b and b′ domains of an “open”, oxidized wPDI (wPDIO) which serves as the acceptor state of substrate. The repetitive sequence is partially folded (compressed) in wPDIO, and is further folded in the thermodynamically favored, subsequent conformational transition of wPDIO to reduced wPDI (wPDIR). Compared with the artificially designed one, the naturally designed repetitive sequence is better recognized and more intensively folded by wPDI for its later unfold as the molecular basis of dough extension.