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Background The widespread usage of protein expression systems in Escherichia coli (E. coli) is a workhorse of molecular biology research that has practical applications in biotechnology industry, including the production of pharmaceutical drugs. Various factors can strongly affect the successful construction and stable maintenance of clones and the resulting biosynthesis levels. These include an appropriate selection of recombinant hosts, expression systems, regulation of promoters, the repression level at an uninduced state, growth temperature, codon usage, codon context, mRNA secondary structure, translation kinetics, the presence/absence of chaperons and others. However, optimization of the growth medium’s composition is often overlooked. We systematically evaluate this factor, which can have a dramatic effect on the expression of recombinant proteins, especially those which are toxic to a recombinant host. Results Commonly used animal tissue- and plant-based media were evaluated using a series of clones in pET vector, containing expressed Open Reading Frames (ORFs) with a wide spectrum of toxicity to the recombinant E. coli: (i) gfpuv (nontoxic); (ii) tp84_28—which codes for thermophilic endolysin (moderately toxic); and (iii) tthHB27IRM—which codes for thermophilic restriction endonuclease-methyltransferase (REase-MTase)—RM.TthHB27I (very toxic). The use of plant-derived peptones (soy peptone and malt extract) in a culture medium causes the T7-lac expression system to leak. We show that the presence of raffinose and stachyose (galactoside derivatives) in those peptones causes premature and uncontrolled induction of gene expression, which affects the course of the culture, the stability of clones and biosynthesis levels. Conclusions The use of plant-derived peptones in a culture medium when using T7-lac hybrid promoter expression systems, such as Tabor-Studier, can lead to uncontrolled production of a recombinant protein. These conclusions also extend to other, lac operator-controlled promoters. In the case of proteins which are toxic to a recombinant host, this can result in mutations or deletions in the expression vector and/or cloned gene, the death of the host or highly decreased expression levels. This phenomenon is caused by the content of certain saccharides in plant peptones, some of which (galactosides) may act as T7-lac promoter inducer by interacting with a Lac repressor. Thus, when attempting to overexpress toxic proteins, it is recommended to either not use plant-derived media or to use them with caution and perform a pilot-scale evaluation of the derepression effect on a case-by-case basis.

Background While the rapidly increasing global population has led to a dramatically increased demand for the agricultural production, there have been heavy economic losses owing to various pest attacks on different food crops. The advancement of various biotechnological techniques have come as a boon in addressing the global concern and leads to the development of novel varieties that have proven to be highly economical, pesticide resistant and environmentally safe. Main body The present review was aimed to update the recent developments that have taken place in the field of crop production. Major focus was laid predominantly on such genes that have demonstrated positive effects and proved to be of commercial success at the market primarily due to the development of pest-resistant transgenic food crops with expression of Bacillus thuringiensis toxins. This technology has been effective against a wide range of pests including coleopterans, lepidopterans, hemipterans, dipterans, strongylida (nematodes) and rhabditida. In similar lines various plant derived toxic proteins were also discussed along with different genes that code for insect resistant proteins such as δ-endotoxins and secreted toxins. This article also helps in understanding the structural features of the genes that are endowed with insect resistance followed by their mechanism of action on pests. Further the role of secondary metabolites in controlling the pests was addressed. The Pros and Cons of existing tools of insect pest management were demonstrated. Conclusions Novel technologies are necessary in crop improvement to progress the pace of the breeding programs, to confer insect resistance in crop plants. Therefore, the future aim of crop biotechnology is to engineer a sustainable, multi-mechanistic resistance to insect pests considering the diversity of plant responses to insect attack.

For the proteins that cannot be expressed exactly by cell expression technology (e.g., proteins with multiple posttranslational modifications or toxic proteins), chemical synthesis is an important substitute. Given the limited peptide length offered by solid-phase peptide synthesis invented by Professor Merrifield, peptide ligation plays a key role in long peptide or protein synthesis by ligating two small peptides to a long one. Moreover, high-molecular-weight proteins must be synthesized using two or more peptide ligation steps, and sequential peptide ligation is such an efficient way. In this paper, we reviewed the development of chemical protein synthesis, including solid-phase peptide synthesis, chemical ligation, and sequential chemical ligation.

With advancements in synthetic biology, the cost and the time needed for designing and synthesizing customized gene products have been steadily decreasing. Many research laboratories in academia as well as industry routinely create genetically engineered proteins as a part of their research activities. However, manipulation of protein sequences could result in unintentional production of toxic proteins. Therefore, being able to identify the toxicity of a protein before the synthesis would reduce the risk of potential hazards. Existing methods are too specific, which limits their application. Here, we extended general function prediction methods for predicting the toxicity of proteins. Protein function prediction methods have been actively studied in the bioinformatics community and have shown significant improvement over the last decade. We have previously developed successful function prediction methods, which were shown to be among top-performing methods in the community-wide functional annotation experiment, CAFA. Based on our function prediction method, we developed a neural network model, named NNTox, which uses predicted GO terms for a target protein to further predict the possibility of the protein being toxic. We have also developed a multi-label model, which can predict the specific toxicity type of the query sequence. Together, this work analyses the relationship between GO terms and protein toxicity and builds predictor models of protein toxicity.

The threat of biological and chemical terror acts remains a growing worldwide concern. There is therefore a need to develop appropriate technology for the detection of chemical and biological warfare agents, with early identification intended for use by first responders. Here, we disclose the developed autonomous air sampling and detection system for evaluation of the presence of chemical and biological warfare agents that can be harmful to the population. The current device utilizes the designed mist generator-assisted air collection system (338 l min−1) and biosensing chip technologies, such as electrochemical measurement, Au nanoparticle-based localized surface plasmon resonance, and rapid microfluidic chip PCR for detection of minute concentrations lower than the mean lethal dose (LD50) of nerve gases (sarin and VX), toxic proteins (BTX/A/Hc and ricin), and pathogens (anthrax simulant). An operation time of only 5–15 min is needed for the collection and detection; sample preparation is already integrated into the system without the need for direct human intervention. In addition to the system’s sensitivity and ease of use, its portability makes it highly beneficial for first responders, which could aid in immediate risk assessment and mitigation of on-site events. A portable device that can detect dangerous chemical and biological warfare agents at less than the mean lethal dose has been developed. Chemical and biological terrorism represents an increasing threat worldwide. Although various sensors have been developed for detecting toxins and pathogenic agents, there remains a need for a portable device that first responders can use to perform initial risk assessments. Masato Saito of Osaka University in Japan and co-workers have achieved this by combining three detection strategies in one device. The device samples air from the environment and then uses electrochemical measurements to detect nerve gases, gold nanoparticles to detect toxic proteins, and a PCR chip to detect pathogens. Molecules of interest can be detected in 5 to 15 minutes, and the device can be transported in a 30-centimeter cubic case.

Compounds that tether toxic proteins with polyglutamine expansions to autophagosomes promote their autophagic clearance and might, in principle, be suitable for the treatment of associated neurodegenerative diseases.

The article discusses how a chain reaction of toxic proteins may help explain neurodegenerative disorders such as Alzheimer's, Parksinson's, and amyotrophic lateral sclerosis (ALS). Topics include an overview of proteinaceous infectious particle (PrP), called prions, research in the 1980s by Stanley B. Prusiner of the University of California, San Francisco that provided evidence that an infectious agent responsible for the animal diseases, called spongiform encephalopathies, led to the misfolding of a protein called PrP, and the impact of knowledge about how proteins fold into a form that causes others to undergo similar transformations on the prevention and treatment of neurological illnesses.

Proteins are important biomaterials and are generally produced in living cells. Here, we show a novel DNA hydrogel that is capable of producing functional proteins without any living cells. This protein-producing gel (termed 'the P-gel system' or 'P-gel') consists of genes as part of the gel scaffolding. This is the first time that a hydrogel has been used to produce proteins. The efficiency was about 300 times higher than current, solution-based systems. In terms of volumetric yield, the P-gel produced up to 5 mg ml(-1) of functional proteins. The mechanisms behind the high efficiency and yield include improved gene stability, higher local concentration and a faster enzyme turnover rate due to a closer proximity of genes. We have tested a total of 16 different P-gels and have successfully produced all 16 proteins including membrane and toxic proteins, demonstrating that the P-gel system can serve as a general protein production technology.

The previously found wide range in the ratios of avenin or methanol-precipitated fractions to residual proteins was revisited by studying 75 oat varieties, mainly representing landraces from Finland, and included old varieties or selections, cv. Kyto, synthetic hexaploid oats and an Avena strigosa line (HA 71–87). The means of the fraction ratios ranged from 4.17 to 6.46 with significant differences. Samples of 10 narrow-ratio and 10 wide-ratio oats were compared more closely. The wide-ratio sample had significantly higher total protein content and significantly lower content of the methanol-precipitated protein fraction. Therefore, both fractions in general appear to contribute to the ratio of the protein fractions. The wide-ratio sample had significantly lower grain mass and husk-free karyopsis mass. Samples of the extreme ends in the ratios of the protein fractions showed different electrophoretic protein patterns, which was also seen in samples representing the same population of origin. It is evident that polymorphisms in the protein fractions would allow breeding of oat cultivars showing further lowering of proteins putatively toxic to coeliacs assuming oats contain these toxic proteins.

Polyglutamine (polyQ) diseases are a group of neurodegenerative conditions, induced from CAG trinucleotide repeat expansion within causative gene respectively. Generation of toxic proteins, containing polyQ-expanded tract, is the key process to cause neurodegeneration. Till now, although polyQ diseases remain uncurable, numerous therapeutic strategies with great potential have been examined and have been proven to be effective against polyQ diseases, including diverse small biological molecules and many pharmacological compounds mainly through prevention on formation of aggregates and inclusions, acceleration on degradation of toxic proteins and regulation of cellular function. We review promising therapeutic strategies by using Drosophila models of polyQ diseases including HD, SCA1, SCA3 and SBMA.

Results now emerge from a preclinical trial of a heat-shock protein inhibitor in a mouse model of neurodegenerative disease. The data indicate that targeting a misfolded protein for degradation may be a useful therapeutic strategy (pages 1088–1095).

British researchers have made the case that both toxic proteins secreted by Clostridium difficile—toxin A and toxin B—should be jointly targeted. The findings support strategies being pursued by Merck and Progenics Pharmaceuticals.

Submaxillary gland saliva induced by phenylephrine from male mice was highly toxic to guinea-pigs, rats and hamsters, whereas the toxicity was relatively low to mice. One of the toxic components in the saliva was isolated as a kallikrein-like enzyme.