Protein and Peptide Letters最新文献

In recent years, plant-derived bioactive compounds have been developed as antiviral agents. Plants synthesize a variety of compounds, especially peptides, which possess antimicrobial activity. Current studies have shown that some antimicrobial peptides have antiviral activity against a wide range of human DNA and RNA viruses and play an effective role in the treatment of human viral diseases. These peptides act through different mechanisms. They can integrate into the envelope of the target virus or cell membrane of the host, resulting in an unstable membrane. For instance, some peptides prevent the attachment of viral spike proteins to host cells. On the other hand, some peptides may alter the cellular pathways, including DNA replication or protein synthesis, leading to the suppression of viral infection. However, the antiviral activity of peptides can be affected by their chemical and structural properties. In several studies, the properties of antimicrobial (antiviral) peptides were altered by minor modifications, but these changes require tools to predict. Recently, computational approaches have been introduced to analyze the effects of structural modifications on the physicochemical properties, mechanism of action, stability, and activity of peptides. In this mini-review, we will describe the design and function of antiviral peptides derived from plants.

Introduction: Poly (ethylene terephthalate) (PET) is one of the most abundant polyester materials used in daily life and it is also one of the main culprits of environmental pollution. ICCG (F243I/D238C/S283C/Y127G) is an enzyme that performs four modifications on the leaf branch compost keratase (LCC). It shows excellent performance in the hydrolysis of PET and has a great potential in further applications.

Method: Here, we used ICCG to degrade PET particles of various sizes and use the density of attack sites (Γ_attack) and kinetic parameters to evaluate the effect of particle size on enzyme degradation efficiency. We are surprised to observe that there is a certain relationship between K_m and Γ_attack. In order to further confirm the relationship, we obtained three different enzymes (Y95K, M166S and H218S) by site-directed mutagenesis on the basis of ICCG.

Result: The results confirmed that there was a negative correlation between Km and Γattack. In addition, we also found that increasing the affinity between the enzyme and the substrate does not necessarily lead to the increase of degradation rate.

Conclusion: These findings show that the granulation of PET and the selection of appropriate particle size are helpful to improve its industrial application value. At the same time, additional protein engineering to increase ICCG performance is realistic, but it can't be limited to enhance the affinity between enzyme and substrate.

Introduction: Nicotinamide N-methyltransferase (NNMT) catalyzes the N-methylation of nicotinamide with S-adenosine-L-methionine (SAM) as the methyl donor. Abnormal expression of NNMT is associated with many diseases (such as multiple cancers and metabolic and liver diseases), making NNMT a potential therapeutic target. Limited studies concerning the enzymesubstrate/ inhibitor interactions could be found to fully understand the detailed reaction mechanism.

Methods: The binding affinity and ligand binding epitopes of nicotinamide or SAH for binding NNMT and its mutants were determined using saturated transfer difference (STD) nuclear magnetic resonance (NMR) techniques combined with site-directed mutagenesis.

Results: The average dissociation constant of WT NNMT with nicotinamide and S-adenosine homocysteine (SAH) was 5.5 ± 0.9 mM and 1.2 ± 0.3 mM, respectively, while the mutants Y20F and Y20G with nicotinamide were up to nearly 4 times and 20 times that of WT and with SAH nearly 2 times and 5 times that of WT. The data suggested that WT had the highest binding affinity for nicotinamide or SAH, followed by Y20F and Y20G, which was consistent with its catalytic activity.

Conclusion: The binding affinity of nicotinamide and SAH to NNMT and its mutants were obtained by STD NMR in this study. It was found that nicotinamide and SAH bind to WT in a particular orientation, and Y20 is critical for their binding orientation and affinity to NNMT.

Background: PD-L1 and PD1 mainly focused on melanoma, lung cancer and other tumors, while the related studies on early lymph node metastasis of papillary thyroid carcinoma were rarely reported.

Objective: For elucidating the role of programmed death 1 (PD1)/programmed death ligand 1 (PD-L1) pathway in tumor growth of papillary thyroid carcinoma (PTC).

Methods: Human thyroid cancer cell line and human normal thyroid cell line were obtained and transfected with si-PD1 or pCMV3-PD1 for the construction of PD1 knockdown or overexpression models. BALB/c mice were purchased for in vivo studies. Nivolumab was implemented for in vivo inhibition of PD1. Western blotting was performed for determining protein expression, while RTqPCR was used to measure relative mRNA levels.

Results: The PD1 and PD-L1 levels were both significantly upregulated in PTC mice, while the knockdown of PD1 downregulated both PD1 and PD-L1 levels. Protein expression of VEGF and FGF2 was increased in PTC mice, while si-PD1 decreased their expression. Silencing of PD1 using si-PD1 and nivolumab both inhibited tumor growth in PTC mice.

Conclusion: Suppressing PD1/PD-L1 pathway significantly contributed to the tumor regression of PTC in mice.

Background: As a peptide originally discovered from Conus achates by mass spectrometry and cDNA sequencing, Ac6.4 contains 25 amino acid residues and three disulfide bridges. Our previous study found that this peptide possesses 80% similarity to MVIIA by BLAST and that MVIIA is a potent and selective blocker of N-type voltage-sensitive calcium channels in neurons.

Objective: To recognize the target protein and analgesic activity of Ac6.4 from Conus achates.

Methods: In the present study, we synthesized Ac6.4, expressed the Trx-Ac6.4 fusion protein, tested Ac6.4 for its inhibitory activity against Cav2.2 in CHO cells and investigated Ac6.4 and Trx-Ac6.4 for their analgesic activities in mice.

Results: Data revealed that Ac6.4 had strong inhibitory activity against Cav2.2 (IC₅₀ = 43.6 nM). After intracranial administration of Ac6.4 (5, 10, 20 μg/kg) and Trx-Ac6.4 (20, 40, 80 μg/kg), significant analgesia was observed. The analgesic effects (elevated pain thresholds) were dose-dependent.

Conclusion: This study expands our knowledge of the peptide Ac6.4 and provides new possibilities for developing Cav2.2 inhibitors and analgesic drugs.

Background: Hevea brasiliensis is severely affected by the fungal disease caused by Phytophthora spp. Significant loss of rubber yield is widespread and extensive use of chemical fungicides has resulted in health and environmental problems.

Objective: This work aims to extract and identify the latex serum peptides from a disease tolerant clone of H. brasiliensis, and study the inhibitory efficacy against pathogenic bacteria and fungi.

Methods: Serum peptides were extracted from H. brasiliensis BPM24 using mixed lysis solution. Low molecular weight peptides were screened and fractionated by solid-phase extraction and then identified by tandem mass spectrometry. Total and fractionated serum peptides were assayed for bacterial and fungal inhibition using broth microdilution and poisoned food methods. An inhibitory control study in the greenhouse was also performed using susceptible clones for pre and postinfection with Phytophthora spp.

Results: Forty-three serum peptide sequences were successfully identified. Thirty-four peptides matched with the proteins associated with plant defense response signaling, host resistance, and adverse environmental factors. The inhibitory study of total serum peptides demonstrated antibacterial and anti-fungal properties. The greenhouse study exhibited disease inhibitory efficacy of 60% for the treatment of Phytophthora spp. in post-infected plants and 80% for pre-treated samples.

Conclusion: Latex serum peptides from disease tolerant H. brasiliensis revealed several proteins and peptides associated with plant defense and disease resistance. The peptides play a vital role for defense against bacteria and fungi pathogens, including Phytophthora spp. Enhanced disease protection can be obtained when the extracted peptides were applied to the susceptible plants before exposure to the fungi. These findings provided an insight and may pave the way for the development of biocontrol peptides from natural resources.

Aims: Further investigation on the mechanism of action of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in NSCLC would shed light on the understanding of TRAIL resistance and provide new clues for the counter-strategy.

Background: Cellular FLICE-inhibitory protein (c-FLIP) is a critical inhibitor of TRAIL-induced apoptosis. Our previous study suggested that glycogen synthase kinase 3β (GSK3β) positively regulated c-FLIP expression in human lung adenocarcinoma cells. Meanwhile, other studies reported that c-FLIP was degraded by HECT-type E3 ligase ITCH (Itchy E3 Ubiquitin Protein Ligase) via the proteasome pathway.

Objective: We will explore whether ITCH is involved in the expression regulation of c-FLIP positively controlled by GSK3β during the treatment of TRAIL.

Methods: Human lung adenocarcinoma cells were used to stably overexpress and knockdown GSK3β. Quantitative real-time PCR (qRT-PCR) assay was used to test the expressional level of mRNA of genes. Western blot analysis was employed to detect the expression of proteins at the protein level. siRNA of ITCH was used to knock down its expression. TRAIL treatment was used to cause apoptosis.

Results: In the present study, we have confirmed the degradation of c-FLIP by ITCH protein and the downregulation of ITCH expression by GSK3β in lung adenocarcinoma cells. Moreover, ITCH silencing reversed the downregulation of c-FLIP protein caused by GSK3β-knockdown in the cells. Accordingly, TRAIL-induced apoptosis facilitated by GSK3β knockdown was blocked by the combined interference of ITCH.

Conclusion: These results suggested that GSK3β/ITCH axis regulated the stability of c-FLIP and influenced TRAIL-induced apoptosis. Taken together, our study revealed a GSK3β/ITCH/c-FLIP axis, which counteracts TRAIL-induced apoptosis in human lung adenocarcinoma cells.

Background: Protease inhibitors (PIs) have attracted attention due to their important roles in plant defense.

Objective: The objective of this work was to characterize and evaluate the antimicrobial activity of the peptides of a family of serine PIs from Capsicum chinense Jacq. seeds.

Methods: Initially, PIs were extracted from the seeds and subjected to purification by chromatography, resulting in three different peptide enriched fractions (PEFs) termed PEF1, PEF2 and PEF3. Subsequently, the PEF3 was subjected to trypsin inhibition assays, α-amylase activity assays, antimicrobial activity assays on phytopathogenic fungi, and assays to determine the likely mechanisms of action.

Results: The PEF3 was composed of three protein bands with molecular masses ranging between 6 and 14 kDa. The amino acid residues of the ~6 kDa band showed high similarity with serine PIs. PEF3 inhibited the activity of the enzymes trypsin, human salivary α-amylase, and Tenebrio molitor larval α-amylase and inhibited the growth of phytopathogenic fungi, showing 83.7% loss of viability in Fusarium oxysporum. PEF3 induced reactive oxygen species in Colletotrichum lindemuthianum and F. oxysporum to dissipate their mitochondrial membrane potential and activated caspases in C. lindemuthianum.

Conclusion: Our results reinforce the importance of PIs in plant defense mechanisms against phytopathogenic fungi as well as in their biotechnological applications for the control of plant pathogens.

Estrogen plays a key role in the development and progression of many malignant tumours, and the regulation of estrogen levels involves several metabolic pathways. Among these pathways, estrogen sulfotransferase (SULT1E1) is the enzyme with the most affinity for estrogen and is primarily responsible for catalysing the metabolic reaction of estrogen sulphation. Relevant studies have shown significant differences in the expression of SULT1E1 in different malignant tumours, suggesting that SULT1E1 plays a dual role in malignant tumours, both inhibiting the growth of malignant tumours and promoting their development. In addition, the expression level of SULT1E1 may be regulated by a variety of factors, which in turn affect the growth and therapeutic effects of malignant tumours. The aim of this paper is to review the mechanism of action of SULT1E1 in malignant tumours and the mechanisms that are regulated, in order to provide potential targets for the treatment of malignant tumour patients in the future and theoretical support for the realisation of more personalised and effective therapeutic regimens.

Background: LinB, as a Haloalkane dehalogenase, has good catalytic activity for many highly toxic and recalcitrant compounds, and can realize the elimination of chemical weapons HD in a green non-toxic mode.

Objectives: In order to display Haloalkane dehalogenase LinB on the surface of Bacillus subtilis spore.

Methods: We have constituted the B. subtilis spore surface display system of halogenated alkanes dehalogenase LinB by gene recombination.

Results: Data revealed that LinB can display on spore surface successfully. The hydrolyzing HD analogue 2-chloroethyl ethylsulfide (2-CEES) activity of displayed LinB spores was 4.30±0.09 U/mL, and its specific activity was 0.78±0.03U/mg. Meanwhile, LinB spores showed a stronger stress resistance activity on 2-CEES than free LinB. This study obtained B. subtilis spores of LinB (phingobium japonicum UT26) with enzyme activity that was not reported before.

Conclusion: Spore surface display technology uses resistance spore as the carrier to guarantee LinB activity, enhances its stability, and reduces the production cost, thus expanding the range of its application.