Functional properties of a new low-molecular-weight glutenin subunit gene from a bread wheat cultivar

Glucose-conjugated glutenin nanoparticles for selective targeting and delivery of camptothecin into breast cancer cells

Receptor-mediated drug delivery systems are a promising tool for targeting malignant cells to suppress/inhibit the malignancy without disturbing healthy cells. Protein-based nanocarrier systems possess numerous advantages for the delivery of variety of chemotherapeutics, including therapeutic peptides and genes. In the present work, glucose-conjugated camptothecin-loaded glutenin nanoparticles (Glu-CPT-glutenin NPs) were fabricated to deliver camptothecin to MCF-7 cells via GLUT-1 transporter protein. Initially, Glu-conjugated glutenin polymer was successfully synthesized through reductive amination reaction, and this was confirmed by FTIR and 13C-NMR. Then, camptothecin (CPT) was loaded into Glu-conjugated glutenin polymer forming Glu-CPT-glutenin NPs. The nanoparticles were studied for their drug releasing capacity, morphological shape, size, physical nature, and zeta potential. The fabricated Glu-CPT-glutenin NPs were found to be spherical in shape and amorphous in nature with 200-nm size range and a zeta potential of - 30 mV. Furthermore, MTT assay using Glu-CPT-glutenin NPs confirmed concentration-dependent cytotoxicity against MCF-7 cells after 24-h treatment, and IC50 was found to be 18.23 μg mL-1. In vitro cellular uptake study demonstrated that the Glu-CPT-glutenin NPs had enhanced endocytosis and delivered CPT in MCF-7 cells. A typical apoptotic morphological change of condensed nuclei and distorted membrane bodies was found after treatment with IC50 concentration of NPs. The released CPT from NPs also targeted mitochondria of MCF-7 cells, significantly increasing the level of reactive oxygen species and causing the damage of mitochondrial membrane integrity. These outcomes confirmed that the wheat glutenin can positively serve as a significant delivery vehicle and enhance the anticancer potential of this drug.

Characterization of novel LMW-i genes with nine cysteine residues from Chinese wheat landraces (Triticum aestivum L.) and analysis of their functional properties on dough mixing

The low-molecular-weight glutenin subunits (LMW-GS) with extra cysteine numbers have attracted great research interest for their potential quality value. In this study, 14 LMW-i type genes (YD1-YD14) were isolated from three types of Chinese wheat landraces; and nine of 14 genes (YD1-YD9) had nine cysteines, and the other five genes contained eight cysteines. Phylogenic analysis suggested that all 14 LMW-i genes were related to Glu-A3-1 variants Glu-A3-17/FJ 549934 and Glu-A3-15/FJ 549932. Six randomly selected genes, five genes including YD 1 with nine cysteines and the remaining one with eight cysteines, were successfully expressed in bacteria as mature proteins with a molecular mass of ~ 46 kDa. These proteins were traced to corresponding seed storage proteins for having similar elution times in reverse phase high-performance liquid chromatography (RP-HPLC) profiles. Mass spectrometry verified that bacterial expressed protein pET-30a-YD1 was LMW-i. Dough mixing experiments for incorporation of 50 mg pET-30a-YD1 proteins into the base flour of weak gluten wheat cv. "Chuannong 16" indicated that the dough strength of mixing flours was noticeably weaker than that of the control, which was reflected by mixing parameters in 8-min curve width, peak width, peak height, mixing time, and right of peak slope. The results suggested that the LMW-i genes with nine cysteine residues in the present study contributed to inferior quality properties for wheat flour.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03044-8.

Low-molecular-weight glutenin subunits from the 1U genome of Aegilops umbellulata confer superior dough rheological properties and improve breadmaking quality of bread wheat

BACKGROUND

Wheat-related genomes may carry new glutenin genes with the potential for quality improvement of breadmaking. In this study, we estimated the gluten quality properties of the wheat line CNU609 derived from crossing between Chinese Spring (CS, Triticum aestivum L., 2n = 6x = 42, AABBDD) and the wheat Aegilops umbellulata (2n = 2x = 14, UU) 1U(1B) substitution line, and investigated the function of 1U-encoded low-molecular-weight glutenin subunits (LMW-GS).

RESULTS

The main quality parameters of CNU609 were significantly improved due to introgression of the 1U genome, including dough development time, stability time, farinograph quality number, gluten index, loaf size and inner structure. Glutenin analysis showed that CNU609 and CS had the same high-molecular-weight glutenin subunit (HMW-GS) composition, but CNU609 carried eight specific 1U genome-encoded LMW-GS. The introgression of the 1U-encoded LMW-GS led to more and larger protein body formation in the CNU609 endosperm. Two new LMW-m type genes from the 1U genome, designated Glu-U3a and Glu-U3b, were cloned and characterized. Secondary structure prediction implied that both Glu-U3a and Glu-U3b encode subunits with high α-helix and β-strand content that could benefit the formation of superior gluten structure.

CONCLUSION

Our results indicate that the 1U genome has superior LMW-GS that can be used as new gene resources for wheat gluten quality improvement. © 2017 Society of Chemical Industry.

Low molecular weight glutenin subunit gene Glu-B3h confers superior dough strength and breadmaking quality in wheat (Triticum aestivum L.)

Low molecular weight glutenin subunit is one of the important quality elements in wheat (Triticum aestivum L.). Although considerable allelic variation has been identified, the functional properties of individual alleles at Glu-3 loci are less studied. In this work, we performed the first comprehensive study on the molecular characteristics and functional properties of the Glu-B3h gene using the wheat cultivar CB037B and its Glu-B3 deletion line CB037C. The results showed that the Glu-B3h deletion had no significant effects on plant morphological or yield traits, but resulted in a clear reduction in protein body number and size and main quality parameters, including inferior mixing property, dough strength, loaf volume, and score. Molecular characterization showed that the Glu-B3h gene consists of 1179 bp, and its encoded B-subunit has a longer repetitive domain and an increased number of α-helices, as well as higher expression, which could contribute to superior flour quality. The SNP-based allele-specific PCR markers designed for the Glu-B3h gene were developed and validated with bread wheat holding various alleles at Glu-B3 locus, which could effectively distinguish the Glu-B3h gene from others at the Glu-B3 locus, and have potential applications for wheat quality improvement through marker-assisted selection.

High-level expression of LMW-GS and α-gliadin genes promoted by the expressed tag sequence of 5' end in Escherichia coli

Wheat storage protein genes, especially low molecular weight glutenin subunit (LMW-GS) and gliadin genes are difficult to be expressed in Escherichiacoli, mainly due to the presence of highly repetitive sequences. In order to establish a high efficiency expression system for these genes, five different expression plasmids combining with 9 genes, viz. 6 LMW-GS and 3 α-gliadin genes isolated from common wheat and related species, were studied for heterologous expression in E. coli. In this study, when an expressed tag sequence encoding signal peptide, His-S or GST-tag was fused to the 5' end of LMW-GS or gliadin gene as the leading sequence, all recombination genes could be stably expressed at a high level. On the contrast, as expected, the inserted genes encoding mature protein failed without an expressed tag sequence. This result indicated that using expressed tag sequences as leading sequences could promote LMW-GS and gliadin genes to be well expressed in E. coli. Further transcriptional analysis by quantitative real-time PCR (qRT-PCR) showed transcription levels of recombination genes (e.g. GST-Glutenin, His-S-Glutenin and SP(∗)-His-Glutenin) were 4-fold to 33-fold higher than those of the LMW-GS genes, which suggested these expressed tag sequences might play an important role in stimulating transcription. The possible molecular mechanism under this phenomenon was discussed.

Virus-induced gene-silencing in wheat spikes and grains and its application in functional analysis of HMW-GS-encoding genes

BACKGROUND

The Barley stripe mosaic virus (BSMV)-based vector has been developed and used for gene silencing in barley and wheat seedlings to assess gene functions in pathogen- or insect-resistance, but conditions for gene silencing in spikes and grains have not been evaluated. In this study, we explored the feasibility of using BSMV for gene silencing in wheat spikes or grains.

RESULTS

Apparent photobleaching on the spikes infected with BSMV:PDS at heading stage was observed after 13 days post inoculation (dpi), and persisted until 30 dpi, while the spikes inoculated with BSMV:00 remained green during the same period. Grains of BSMV:PDS infected spikes also exhibited photobleaching. Molecular analysis indicated that photobleached spikes or grains resulted from the reduction of endogenous PDS transcript abundances, suggesting that BSMV:PDS was able to induce PDS silencing in wheat spikes and grains. Inoculation onto wheat spikes from heading to flowering stage was optimal for efficient silencing of PDS in wheat spikes. Furthermore, we used the BSMV-based system to reduce the transcript level of 1Bx14, a gene encoding for High-molecular-weight glutenin subunit 1Bx14 (HMW-GS 1Bx14), by 97 % in the grains of the BSMV:1Bx14 infected spikes at 15 dpi, compared with that in BSMV:00 infected spikes, and the reduction persisted until at least 25 dpi. The amount of the HMW-GS 1Bx14 was also detectably decreased. The percentage of glutenin macropolymeric proteins in total proteins was significantly reduced in the grains of 1Bx14-silenced plants as compared with that in the grains of BSMV:00 infected control plants, indicating that HMW-GS 1Bx14 is one of major components participating in the formation of glutenin macropolymers in wheat grains.

CONCLUSION

This is one of the first reports of successful application of BSMV-based virus-induced-gene-silencing (VIGS) for gene knockdown in wheat spikes and grains and its application in functional analysis of the 1Bx14 gene. The established BSMV-VIGS system will be very useful in future research on functional analysis of genes contributing to grain quality and the metabolic networks in developing seeds of wheat.

Molecular characterisation of the low-molecular weight glutenin subunit genes of tall wheatgrass and functional properties of one clone Ee34

Wild tall wheatgrass (Lophopyrum elongatum L., 2x = 14) is an important resource for improving bread wheat (Titicum aestivum L.), including HMW-GS and LMW-GS relevant to end-use quality of the wheat flour. A set of 14 distinct sequences were amplified from the genomic DNA of the tall wheatgrass, using degenerate primers targeted at Glu-3, the locus containing the genes encoding the low-molecular weight glutenin subunits (LMW-GS). Three sequences contained an internal stop codon and were classified as pseudogenes. The other 11 all consisted of a single intron-less intact open-reading frame. An alignment of deduced protein sequences showed that the primary structure of all 11 sequences was similar to that of wheat and other wheat-related grass Glu-3 genes. All 11 sequences carried the 14 amino acid residue N-terminal motif MESNIIISFLK/RPWL, and were classified as LMW-m genes, based on the identity of the first amino acid of the mature protein. All but one of the sequences contained seven cysteine residues (the exception had 6). Their repetitive domain differs significantly from that present in Glu-3 genes isolated from the close relative intermediate wheatgrass (Thinopyrum Intermedium, 6x). A phylogenetic analysis showed that the tall wheatgrass sequences were closely related to those of the intermediate wheatgrass, but only distantly so to those from decaploid tall wheatgrass. One of the 11 LMW-GS peptides with a free-cysteine residue was heterologously expressed in E. coli and purified in sufficient scale to perform a flour supplementation test. This showed that the dough strength of bread wheat flour was significantly increased by the presence of the tall wheatgrass LMW-GS.

Molecular characterization of LMW-GS genes from a somatic hybrid introgression line II-12 between Triticum aestivum and Agropyron elongatum in relation to quick evolution

In order to exploit the evolution and find novel low-molecular-weight glutenin subunit (LMW-GS) for improvement of common wheat quality, thirteen variants from a somatic hybrid introgression line II-12 between Triticum aestivum cv. Jinan 177 (JN177) and Agropyron elongatum were characterized via genomic PCR. Four clones were pseudogenes because they contained an internal stop codon. The remaining nine variants contained intact open reading frames (ORFs). Sequence alignment indicates that the proteins deduced from the nine ORFs have similar primary structure with LMW-GS cloned from its parents previously. However, they have some unique modifications in the structures. For example, EU292737 contains not only an extra Cys residue in the C-terminal domain but also a long repetitive domain. Both EU159511 and EU292738 start their first Cys residue in the N-terminal repetitive domain, but not in the N-conserved domain traditionally. These structural alterations may have positive contributions to wheat flour quality. The results of phylogeny showed that most LMW-GS variances from II-12 were homologous to those from parent JN177 and other wheat lines. The reason for quick evolution of LMW-GS in II-12 was discussed.