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Journal of Biological Inorganic... Dec 2023Circular permutation (CP) is a technique by which the primary sequence of a protein is rearranged to create new termini. The connectivity of the protein is altered but...
Circular permutation (CP) is a technique by which the primary sequence of a protein is rearranged to create new termini. The connectivity of the protein is altered but the overall protein structure generally remains unperturbed. Understanding the effect of CP can help design robust proteins for numerous applications such as in genetic engineering, optoelectronics, and improving catalytic activity. Studies on different protein topologies showed that CP usually affects protein stability as well as unfolding rates. Though a significant number of proteins contain metals or other cofactors, reports of metalloprotein CPs are rare. Thus, we chose a bacterial metalloprotein, azurin, and its CP within the metal-binding site (cpF114). We studied the stabilities, folding, and unfolding rates of apo- and Zn-bound CP azurin using fluorescence and circular dichroism. The introduced CP had destabilizing effects on the protein. Also, the folding of the Zn-CP protein was much slower than that of the Zn-WT or apo-protein. We compared this study to our previously reported azurin-cpN42, where we had observed an equilibrium and kinetic intermediate. cpF114 exhibits an apparent two-state equilibrium unfolding but has an off-pathway kinetic intermediate. Our study hinted at CP as a method to modify the energy landscape of proteins to alter their folding pathways. WT azurin, being a faster folder, may have evolved to optimize the folding rate of metal-bound protein compared to its CPs, albeit all of them have the same structure and function. Our study underscores that protein sequence and protein termini positions are crucial for metalloproteins. TOC Figure. (Top) Zn-azurin WT structure (PDB code: 1E67) and 2-D topology diagram of Zn-cpF114 azurin. (Bottom) Cartoon diagram representing folding (red arrows) and unfolding (blue arrows) of apo- and Zn- WT and cpF114 azurins. The width of the arrows represents the rate of the corresponding processes.
Topics: Azurin; Protein Folding; Catalytic Domain; Apoproteins; Metals; Circular Dichroism; Kinetics
PubMed: 37957357
DOI: 10.1007/s00775-023-02023-z -
Alternative Therapies in Health and... Oct 2023Osteosarcoma (OS) is the most common bone malignancy, with a high mortality rate in adolescents. Despite advancements in therapeutic interventions, OS prognosis remains...
BACKGROUND
Osteosarcoma (OS) is the most common bone malignancy, with a high mortality rate in adolescents. Despite advancements in therapeutic interventions, OS prognosis remains poor due to drug resistance. P21, a cyclin-dependent kinase inhibitor, plays a critical role in cell cycle regulation and has been implicated in OS pathogenesis. Cisplatin (DDP) is a conventional chemotherapeutic agent for OS, but its efficacy is often limited due to drug resistance. Azurin, a bacterial redox protein, has been reported to exhibit antitumor activity. However, its interaction with P21 in OS remains unexplored. In this study, we sought to investigate the impact of azurin on the cytotoxic effect of DDP against OS cells in relation to P21 expression.
METHODS
Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were used to determine the level of p21 and apoptosis-related factors in U2OS cells. A Cell Counting Kit-8 (CCK-8) was used to examine the effects of azurin-p21 on the U2OS cell proliferation rate. Flow cytometry (FCM)was used to analyze the impact of azurin-P21 on the apoptosis/cell cycle. Enzyme-linked immunosorbent assay (ELISA) was used to analyze the effects of azurin-P21 on the secretion of oxygen free radicals, glutathione and glutathione peroxidase.
RESULTS
Azurin exhibited significant cytotoxic activity against U2OS cells expressing wild-type (WT) P21, with minimal impact on SAOS-2 and MG63 cells lacking endogenous P21. Azurin treatment resulted in increased expression of procaspase-3 and Bax, decreased expression of B-cell lymphoma-2 (Bcl-2) and a consequential increase in apoptosis. The depletion of P21 attenuated these effects, suggesting the crucial role of P21 in azurin-mediated cytotoxicity. Furthermore, azurin synergistically enhanced the cytotoxic effect of DDP against U2OS cells, which was mitigated by P21 depletion.
CONCLUSIONS
Our findings demonstrated that azurin selectively induces apoptosis and cell cycle arrest in U2OS cells, which is mediated via P21. This study highlights the potential of azurin as a sensitizer for DDP in the treatment of OS. Future studies on DDP-resistant OS cells may further elucidate the clinical relevance of our findings.
PubMed: 37442187
DOI: No ID Found -
Microbial Pathogenesis Dec 2023Pseudomonas aeruginosa is a Gram-negative bacteria and it has been demonstrated that immunization with the outer membrane proteins of the microbe produces most of the... (Review)
Review
Pseudomonas aeruginosa is a Gram-negative bacteria and it has been demonstrated that immunization with the outer membrane proteins of the microbe produces most of the relevant human antibodies. The peritrichous P. aeruginosa strain with MSHA fimbriae (PA-MSHA strain) has been found to be effective in the inhibition of growth and proliferation of different types of cancer cells. Furthermore, it has been revealed that PA-MSHA exhibits cytotoxicity because of the presence of MSHA and therefore it possesses anti-carcinogenic ability against different types of human cancer cell lines including, gastric, breast, hepatocarcinoma and nasopharyngeal cells. Studies have revealed that PA-MSHA exhibits therapeutic potential against cancer growth by induction of apoptosis, arrest of cell cycle, activating NF-κB/TLR5 pathway, etc. In China, PA-MSHA injections have been approved for the treatment of malignant tumor patients from very long back. The present review article demonstrates the therapeutic potential of PA-MSHA against various types of human cancers and explains the underlying mechanism.
Topics: Humans; Signal Transduction; Pseudomonas aeruginosa; Hemagglutinins; Mannose; Cell Proliferation; Liver Neoplasms
PubMed: 37871855
DOI: 10.1016/j.micpath.2023.106422 -
Life Sciences Jul 2023Preliminary studies have identified the use of probiotics as a potential treatment strategy against colorectal cancer (CRC). However, natural probiotics lack direct...
AIMS
Preliminary studies have identified the use of probiotics as a potential treatment strategy against colorectal cancer (CRC). However, natural probiotics lack direct tumor-targeting and tumor-killing activity in the intestine. This study aimed to construct a tumor-targeting engineered probiotic to combat CRC.
MAIN METHODS
Standard adhesion assay was performed to analyze the adherence ability of tumor-binding protein HlpA to CT26 cells. CCK-8 assay, Hoechst 33258 staining and flow cytometry analysis were used for examining cytotoxicity of tumoricidal protein azurin toward CT26 cells. An engineered probiotic Ep-AH harboring azurin and hlpA genes was developed using Escherichia coli Nissle 1917 (EcN) chassis. Antitumor effects of Ep-AH were evaluated in the azoxymethane (AOM) and dextran sodium sulfate salt (DSS)-induced CRC mice. Moreover, analysis of gut microbiota was conducted via fecal 16S rRNA gene sequencing and shotgun metagenomic sequencing.
KEY FINDINGS
Azurin caused a dose-dependent increase of apoptosis in CT26 cells. Ep-AH treatment reversed weight loss (p < 0.001), fecal occult blood (p < 0.01), and shortening of colon length (p < 0.001) than model group, as well as reducing tumorigenesis by 36 % (p < 0.001). Both Ep-H and Ep-A (EcN expressing HlpA or azurin) were less effective than Ep-AH. Furthermore, Ep-AH enriched the members of beneficial bacteria (e.g., Blautia and Bifidobacterium) and reversed abnormal changes of genes associated with several metabolic pathways (e.g., lipopolysaccharide biosynthesis).
SIGNIFICANCE
These results demonstrated that Ep-AH had excellent therapeutic benefits on cancer remission and gut microbiota modulation. Our study provides an effective strategy for anti-CRC treatment.
Topics: Animals; Mice; Gastrointestinal Microbiome; RNA, Ribosomal, 16S; Azurin; Carcinogenesis; Cell Transformation, Neoplastic; Probiotics; Colorectal Neoplasms; Escherichia coli; Dextran Sulfate; Disease Models, Animal; Colitis
PubMed: 37100380
DOI: 10.1016/j.lfs.2023.121709 -
Journal of the American Chemical Society Sep 2023Much progress has been made in understanding the roles of the secondary coordination sphere (SCS) in tuning redox potentials of metalloproteins. In contrast, the impact...
Much progress has been made in understanding the roles of the secondary coordination sphere (SCS) in tuning redox potentials of metalloproteins. In contrast, the impact of SCS on reactivity is much less understood. A primary example is how copper proteins can promote -nitrosylation (SNO), which is one of the most important dynamic post-translational modifications, and is crucial in regulating nitric oxide storage and transportation. Specifically, the factors that instill Cu with -nitrosylating capabilities and modulate activity are not well understood. To address this issue, we investigated the influence of the primary and secondary coordination sphere on Cu-catalyzed -nitrosylation by developing a series of azurin variants with varying catalytic capabilities. We have employed a multidimensional approach involving electronic absorption, S and Cu K-edge XAS, EPR, and resonance Raman spectroscopies together with QM/MM computational analysis to examine the relationships between structure and molecular mechanism in this reaction. Our findings have revealed that kinetic competency is correlated with three balancing factors, namely Cu-S bond strength, Cu spin localization, and relative S(p) vs S(p) contributions to the ground state. Together, these results support a reaction pathway that proceeds through the attack of the Cu-S bond rather than electrophilic addition to Cu or radical attack of S. The insights gained from this work provide not only a deeper understanding of SNO in biology but also a basis for designing artificial and tunable SNO enzymes to regulate NO and prevent diseases due to SNO dysregulation.
Topics: Azurin; Copper; Metalloproteins; Catalysis; Electronics
PubMed: 37696009
DOI: 10.1021/jacs.3c07399 -
The Journal of Physical Chemistry... Dec 2023We conducted a theoretical study of electron transport through junctions of the blue-copper azurin from . We found that single-site hopping can lead to either higher or...
We conducted a theoretical study of electron transport through junctions of the blue-copper azurin from . We found that single-site hopping can lead to either higher or lower current values compared to fully coherent transport. This depends on the structural details of the junctions as well as the alignment of the protein orbitals. Moreover, we show how the asymmetry of the curves can be affected by the position of the tip in the junction and that, under specific conditions, such a hopping mechanism is consistent with a fairly low temperature dependence of the current. Finally, we show that increasing the number of hopping sites leads to higher hopping currents. Our findings, from fully quantum calculations, provide deep insight to help guide the interpretation of experimental curves on highly complex systems.
PubMed: 38059566
DOI: 10.1021/acs.jpclett.3c02702 -
Molecular Biotechnology Jun 2024Transfection efficiency of the immortalized human breast epithelial cell line MCF-10A remains an issue that needs to be resolved. In this study, it was aimed to deliver...
Transfection efficiency of the immortalized human breast epithelial cell line MCF-10A remains an issue that needs to be resolved. In this study, it was aimed to deliver a recombinant DNA (pCMV-Azu-GFP) to the MCF-10A cells by the magnetofection method using magnetic nanoparticles (MNPs) and a simple magnet to accelerate the DNA delivery. Surface positively modified silica-coated iron oxide MNPs (MSNP-NH) were produced and characterized via TEM, FTIR, and DLS analyses. The recombinant DNA (rDNA) was obtained by the integration of codon-optimized azurin to produce a fusion protein. Then, rDNA cloned in Escherichia coli cells was validated by sequence analysis. The electrostatically conjugated rDNA on MSNP-NH with an enhancer polyethyleneimine (PEI) was studied by agarose gel electrophoresis and the optimum conditions were determined to apply to the cell. A dose-dependent statistical difference was observed on treated cells based on the MTS test. The expression of the fusion protein after magnetofection was determined using laser scanning confocal microscope imaging and western blot analysis. It was observed that the azurin gene could be transferred to MCF-10A cells by magnetofection. Thus, when the azurin gene is used as a breast cancer treatment agent, it can be expressed in healthy cells without toxic effects.
Topics: Female; Humans; Azurin; Cell Line, Tumor; Codon; DNA, Ribosomal; Escherichia coli; Magnetic Iron Oxide Nanoparticles; Magnetite Nanoparticles; Polyethyleneimine; Recombinant Fusion Proteins; Transfection
PubMed: 37378861
DOI: 10.1007/s12033-023-00798-9 -
Chemical Science May 2024Native chemical ligation (NCL) has been playing an increasingly important role in chemical protein synthesis (CPS). More efficient ligation methods that circumvent the...
Native chemical ligation (NCL) has been playing an increasingly important role in chemical protein synthesis (CPS). More efficient ligation methods that circumvent the requirement of a peptidyl thioester and thiol additive-which allow the following desulfurization or refolding in one pot-are urgently needed for the synthesis of more complex protein targets and in large quantities. Herein, we discover that the weak acyl donor peptidyl -acyl pyrazole can be activated by azole reagents like 3-methylpyrazole or imidazole to facilitate its ligation directly with an N-terminal cysteine peptide. As it requires no thioester or thiol additive, this ligation strategy can be conveniently combined with metal-free desulfurization (MFD) or oxidative protein folding to allow various one-pot protocols. The utility and generality of the strategy are showcased by the total synthesis of ubiquitin an N-to-C sequential ligation-MFD strategy, the semi-synthesis of the copper protein azurin, and the efficient assembly of a sulfated hirudin variant and the cyclotide kalata B1, all in a one-pot fashion.
PubMed: 38817582
DOI: 10.1039/d3sc06697e -
Journal of Molecular Modeling Jun 2024The coherent electron/spin transport in azurin, a species of copper protein, was calculated based on the Landauer model. The research is motivated by the fast electron...
CONTEXT
The coherent electron/spin transport in azurin, a species of copper protein, was calculated based on the Landauer model. The research is motivated by the fast electron transport and spin selectivity/polarization in azurin, which have been reported in relation to the chiral-induced spin selectivity of the peptide structure. The calculated spin polarization of copper proteins was large. This phenomenon was strongly influenced by the spin density of the atoms in the ligand group, whereas the contribution of copper was negligible. The results suggest that spin polarization in copper proteins is enhanced by that of the ligand groups. The predicted spin polarization aligns primarily with the scanning tunneling microscope-based break-junction technique to study the electronic properties of single-molecule junctions.
METHODS
Computational techniques employed in this study are nonequilibrium Green's functions (NEGF) and density functional theory (DFT) based on the Landauer model, implemented using the QuantumATK software (Synopsys Inc.). The Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional was adopted for spin-polarized generalized gradient approximation (SGGA). The valence atomic orbitals were constructed using the wavefunctions of the SIESTA package, which was based on the norm-conserving Troullier-Martins relativistic pseudopotentials for describing core electrons. The mesh used for real-space integration was 150 Ha.
Topics: Azurin; Copper; Models, Molecular; Electron Transport; Density Functional Theory
PubMed: 38890154
DOI: 10.1007/s00894-024-06025-9 -
Bioengineering (Basel, Switzerland) Oct 2023Compared to chemical drugs, therapeutic proteins exhibit higher specificity and activity and are generally well-tolerated by the human body. However, the limitations,...
Compared to chemical drugs, therapeutic proteins exhibit higher specificity and activity and are generally well-tolerated by the human body. However, the limitations, such as poor stability both in vivo and in vitro as well as difficulties in penetrating cell membranes, hinder their widespread application. To overcome the challenges, a highly efficient protocol was developed and implemented for the recombinant expression of the therapeutic protein azurin and secretion into minicells derived from probiotic Nissle 1917. The novel coupled production with a delivery system of therapeutic proteins based on minicells was obtained through purification to enhance protein activity, circulation characteristics, and targeting specificity. This protein drug carrier integrates the production of carrier materials and the loading of expression proteins. The drug carrier also protects the encapsulated polypeptide drugs from enzymatic or gastric acid degradation until they are released. Nissle 1917-derived minicells have natural targeting to colon cancer cells, low toxicity, and can accumulate for a long time after penetrating tumor tissue. This self-produced protein drug delivery system simplified the process of protein preparation, and its inhibitory effect on different types of colon cancer cells was verified by CCK-8 cytotoxicity assay, cancer cell invasion, and migration assay. This work provided a simple method to prepare minicell drug delivery systems for protein drug production and a novel approach for the transport of recombinant protein drugs.
PubMed: 37892918
DOI: 10.3390/bioengineering10101188