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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Refined hyperentanglement purification of two-photon systems for high-capacity quantum communication with cavity-assisted interaction

Hyperentanglement, defined as the entanglement in multiple degrees of freedom (DOFs) of a photonic quantum system, has attracted much attention recently as it can improve the channel capacity of quantum communication largely. Here we present a refined hyperentanglement purification protocol (hyper-EPP) for two-photon systems in mixed hyperentangled states in both the spatial-mode and polarization DOFs, assisted by cavity quantum electrodynamics. By means of the spatial (polarization) quantum state transfer process, the quantum states that are discarded in the previous hyper-EPPs can be preserved. That is, the spatial (polarization) state of a four-photon system with high fidelity can be transformed into another four-photon system with low fidelity, not disturbing its polarization (spatial) state, which makes this hyper-EPP take the advantage of possessing a higher efficiency.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

High-fidelity quantum gates on quantum-dot-confined electron spins in low-Q optical microcavities

We propose some high-fidelity quantum circuits for quantum computing on electron spins of quantum dots (QD) embedded in low-Q optical microcavities, including the two-qubit controlled-NOT gate and the multiple-target-qubit controlled-NOT gate. The fidelities of both quantum gates can, in principle, be robust to imperfections involved in a practical input–output process of a single photon by converting the infidelity into a heralded error. Furthermore, the influence of two different decay channels is detailed. By decreasing the quality factor of the present microcavity, we can largely increase the efficiencies of these quantum gates while their high fidelities remain unaffected. This proposal also has another advantage regarding its experimental feasibility, in that both quantum gates can work faithfully even when the QD-cavity systems are non-identical, which is of particular importance in current semiconductor QD technology.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Aerobic oxidation of alcohols over Ru-Mn-Ce and Ru-Co-Ce catalysts: The effect of calcination temperature

We report two ternary mixed oxides, Ru-Mn-Ce and Ru-Co-Ce, were prepared by a co-precipitation method and used in the aerobic oxidation of alcohols to corresponding aldehydes (ketones). Interestingly, different catalytic results were obtained when these compounds were calcined. The calcination temperature had an adverse effect on the catalytic performance of Ru-Mn-Ce catalysts, while being beneficial to the Ru-Co-Ce catalysts. To illustrate these effects, these materials were characterized using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Temperature-programmed reduction (TPR), Electron paramagnetic resonance (EPR) and other techniques. The data showed that ruthenium oxides were uniformly dispersed in the mixed oxides, and phase transformations occur after calcination. Mn 3 O 4 was transformed to MnO 2 for the Ru-Mn-Ce catalyst, while CoO(OH) was transformed to Co 3 O 4 in the Ru-Co-Ce catalyst. The interactions between ruthenium oxides and Co (Mn)-Ce mixed oxides of the former strengthened while the latter weakened. Calcination decreased the content of adsorbed oxygen and restricted oxygen transfer mechanism in the manganese system, while the opposite effect was observed with the cobalt-containing catalyst. Under optimal reaction conditions, various kinds of alcohols were transformed to corresponding aldehydes (ketones) in high yields over the Ru-Mn-Ce catalyst suggesting these ternary oxides are environmental friendly and economical catalytic systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Kruppel-like factor 2 inhibit the angiogenesis of cultured human liver sinusoidal endothelial cells through the ERK1/2 signaling pathway

Kruppel-like factor 2 (KLF2) is a crucial anti-angiogenic factor. However, its precise role in hepatic angiogenesis induced by liver sinusoidal endothelial cells (LSECs) remain unclear. This study was aimed to evaluate the effect of KLF2 on angiogenesis of LSECs and to explore the corresponding mechanism. Cultured human LSECs were infected with different lentiviruses to overexpress or suppress KLF2 expression. The CCK-8 assay, transwell migration assay and tube formation test, were used to investigate the roles of KLF2 in the proliferation, migration and vessel tube formation of LSECs, respectively. The expression and phosphorylation of ERK1/2 were detected by western blot. We discovered that the up-regulation of KLF2 expression dramatically inhibited proliferation, migration and tube formation in treated LSECs. Correspondingly, down-regulation of KLF2 expression significantly promoted proliferation, migration and tube formation in treated LSECs. Additionally, KLF2 inhibited the phosphorylation of ERK1/2 pathway, followed by the function of KLF2 in the angiogenesis of LSECs disrupted. In conclusion, KLF2 suppressed the angiogenesis of LSECs through inhibition of cell proliferation, migration, and vessel tube formation. These functions of KLF2 may be mediated through the ERK1/2 signaling pathway. - Highlights: • Overexpression of KLF2 inhibits the proliferation and migration of LSECs. • Overexpression of KLF2 inhibits the angiogenesis of LSECs. • ERK1/2 signaling pathway involved in the anti-angiogenic process of KLF2 on LSECs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Apelin-13 upregulates Egr-1 expression in rat vascular smooth muscle cells through the PI3K/Akt and PKC signaling pathways

Previous studies have shown that Apelin-13 upregulates early growth response factor-1 (Egr-1) via the extracellular signal-regulated protein kinase (ERK) signaling pathway. Apelin-13 induces proliferation and migration of vascular smooth muscle cells (VSMCs) as well as the upregulation of osteopontin (OPN) via the upregulation of Egr-1. This study was designed to further explore the activity of Apelin-13 in VSMCs by investigating members of the mitogen-activated protein kinase (MAPK) family, in particular Jun kinase (JNK) and p38 mitogen-activated protein kinase (P38). We also examined whether the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) and protein kinase C (PKC) signaling pathways were involved in the regulation of Egr-1 by Apelin-13. We treated rat aortic VSMCs with Apelin-13 and examined the expression of JNK, p-JNK, P38, and p-P38 to investigate whether Apelin-13-mediated increases in Egr-1 occurred through the JNK and P38 signaling pathways. We then pretreated VSMCs with the Gi protein inhibitor pertussis toxin (PTX) and the Gq inhibitor YM254890, added Apelin-13 and looked for changes in Egr-1 expression. Finally, we pretreated with the PI3K inhibitor LY294002 and the PKC inhibitor GF109203X, and treated with Apelin-13. Our results showed that JNK and P38 did not participate in Apelin-13-mediated increase in Egr-1. Instead, Apelin-13 upregulation of Egr-1 was mediated by a PTX-sensitive Gi protein. Apelin-13 did increase ERK phosphorylation through the PI3K/Akt and PKC signaling pathways, resulting in changes in Egr-1 expression. These data provide important targets for future studies to modulate vascular remodeling. - Highlights: • Apelin-13 mediates Egr-1 upregulation in vascular smooth muscle cells via ERK1/2. • The underlying mechanisms are unknown, but exclude Jnk or p38 pathway activation. • Apelin-13 binds to Gi, activating the PI3K/Akt and PKC signaling cascades. • Consequent ERK phosphorylation results in increased Egr-1 expression. • These novel targets may be potential therapies for vascular remodeling diseases.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

miR-625 suppresses cell proliferation and migration by targeting HMGA1 in breast cancer

Dysregulation of microRNA contributes to the high incidence and mortality of breast cancer. Here, we show that miR-625 was frequently down-regulated in breast cancer. Decrease of miR-625 was closely associated with estrogen receptor (P = 0.004), human epidermal growth factor receptor 2 (P = 0.003) and clinical stage (P = 0.001). Kaplan–Meier and multivariate analyses indicated miR-625 as an independent factor for unfavorable prognosis (hazard ratio = 2.654, 95% confident interval: 1.300–5.382, P = 0.007). Re-expression of miR-625 impeded, whereas knockdown of miR-625 enhanced cell viabilities and migration abilities in breast cancer cells. HMGA1 was confirmed as a direct target of miR-625. The expressions of HMGA1 mRNA and protein were induced by miR-625 mimics, but reduced by miR-625 inhibitor. Re-introduction of HMGA1 in cells expressing miR-625 distinctly abrogated miR-625-mediated inhibition of cell growth. Taken together, our data demonstrate that miR-625 suppresses cell proliferation and migration by targeting HMGA1 and suggest miR-625 as a promising prognostic biomarker and a potential therapeutic target for breast cancer. - Highlights: • miR-625 expression was significantly decreased in breast cancer. • Decrease of miR-625 was associated with poor clinical outcomes and unfavorable overall survival. • miR-625 overexpression inhibits cell proliferation and migration in vitro. • miR-625 directly targets and suppresses the expression of HMGA1.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Long noncoding RNA-MEG3 is involved in diabetes mellitus-related microvascular dysfunction

Microvascular dysfunction is an important characteristic of diabetic retinopathy. Long non-coding RNAs (lncRNAs) play important roles in diverse biological processes. In this study, we investigated the role of lncRNA-MEG3 in diabetes-related microvascular dysfunction. We show that MEG3 expression level is significantly down-regulated in the retinas of STZ-induced diabetic mice, and endothelial cells upon high glucose and oxidative stress. MEG3 knockdown aggravates retinal vessel dysfunction in vivo, as shown by serious capillary degeneration, and increased microvascular leakage and inflammation. MEG3 knockdown also regulates retinal endothelial cell proliferation, migration, and tube formation in vitro. The role of MEG3 in endothelial cell function is mainly mediated by the activation of PI3k/Akt signaling. MEG3 up-regulation may serve as a therapeutic strategy for treating diabetes-related microvascular complications. - Highlights: • LncRNA-MEG3 level is down-regulated upon diabetic stress. • MEG3 knockdown aggravates retinal vascular dysfunction in vivo. • MEG3 regulates retinal endothelial cell function in vitro. • MEG3 regulates endothelial cell function through PI3k/Akt signaling.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Catalpol suppresses osteosarcoma cell proliferation through blocking epithelial-mesenchymal transition (EMT) and inducing apoptosis

Highlights: • Catalpol inhibits cell viability and EMT in osteosarcoma cell lines. • Catalpol induces apoptosis in osteosarcoma cell lines by Bcl-2/Caspase-8 signaling. • Catalpol induces ROS generation and suppresses STAT3 pathway activation. • Catalpol is able to suppresses osteosarcoma growth in vivo. Catalpol, an iridoid glucoside compound, is reported to possess diverse pharmacological actions. However, its effects on osteosarcoma are little to be known. In the present study, we showed that catalpol could strongly suppress osteosarcoma progression. Catalpol dose-dependently reduced the cancer cell viability. The migration of osteosarcoma cells was also consistently suppressed by catalpol treatment using the wound healing and transwell migration analysis. Catalpol reduced the expressions of Kras, receptor for activated C-kinase 1(RACK1) and matrix metalloproteinase (MMP)-2 in a dose-dependent manner, revealing the blockage of migration. Moreover, both intrinsic and extrinsic apoptosis were triggered by catalpol, as evidenced by improved cleaved Caspase-8/-9/-3 and Poly-(ADP-ribose) polymerase (PARP). Release of Cyto-c in cytoplasm and Bax up-regulation in total cells were observed in catalpol-treated cells, while mitochondrial Cyto-c and cellular Bcl-2 were down-regulated by catalpol. Reactive oxygen species (ROS) production was also involved in catalpol-induced cell death. Further, ROS scavenger, N-acetylcysteine (NAC), impeded catalpol-caused apoptosis. And suppression of signal transducer and activator of transcription 3/Janus kinase 2 gene/Src (STAT3/JAK2/Src) was involved in catalpol-induced cell death. In vivo, catalpol showed effective ability to reduce the tumor growth. Our results illustrated that catalpol might be considered as a promising pharmacological agent to suppress osteosarcoma.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

FOXK1 plays an oncogenic role in the development of esophageal cancer

Forkhead box k1 (FOXK1) is a member of the FOX class of transcription factors and it is dysregulated in many solid tumors including hepatocellular carcinoma, gastric cancer, colorectal cancer and prostate cancer. However, the expression status of FOXK1 and its clinical significance in esophageal cancer (EC) is still uncertain. Our study aimed at investigating the significance of FOXK1 expression in human EC and its biological function in the development of EC. We found that FOXK1 was overexpressed in EC tissues compared with corresponding non-tumor tissues using immunohistochemistry. And high FOXK1 expression was related to poor differentiation of EC. The Kaplan-Meier curve indicated that high FOXK1 expression may result in poor prognosis of EC patients. Furthermore, overexpression of FOXK1 in EC9706 cell inhibited cell apoptosis and promoted cell proliferation and migration, and suppression of FOXK1 in EC109 cell obtained reverse results. Our data suggest that FOXK1 plays an oncogenic role in EC pathogenesis and can serve as a therapeutic target for patients with EC. - Highlights: • It's the first time investigating the relationship between FOXK1 and esophageal cancer (EC). • FOXK1 could inhibit cell apoptosis and promote cell proliferation and migration of EC in vitro. • FOXK1 plays an oncogenic role in EC pathogenesis and can serve as a therapeutic target for patients with EC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

LncRNA FABP5P3/miR-589-5p/ZMYND19 axis contributes to hepatocellular carcinoma cell proliferation, migration and invasion

Hepatocellular carcinoma (HCC) contributes to cancer-related deaths greatly every year in the world. However, there is still no radical method for HCC treatment. Here we screened out a lncRNA FABP5P3 that was up-regulated in HCC tissues. Patients with higher FABP5P3 expression displayed poorer survival rate. FABP5P3 depletion in HCC cell lines and sample cells remarkably inhibited the abilities of proliferation, migration and invasion. In mechanism, we showed that FABP5P3 bond to miR-589-5p which served as a tumor suppressor. MiR-589-5p targeted directly the mRNA of ZMYND19 whose function has not been defined in HCC. FABP5P3 promoted HCC development and progression by sponging miR-589-5p and up-regulating ZMYND19 expression. In sum, we showed that FABP5P3/miR-589-5p/ZMYND19 axis regulates cell proliferation and migration in HCC, which may serve as a new target for HCC treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Leptin promotes pulmonary fibrosis development by inhibiting autophagy via PI3K/Akt/mTOR pathway

Highlights: • Leptin expression is associated with the severity of IPF. • Leptin accelerated the TGF-β1 induced epithelial mesenchymal transition of A549 cells. • The pro-fibrogenic effects of leptin occurred through inhibiting autophagy via PI3K/Akt/mTOR pathway. Leptin, a protein-related product of the obesity gene, plays an important role in the pathogenesis of fibrotic diseases including pulmonary fibrosis. As a highly conservative process, autophagy regulates various biological functions. Otherwise, insufficient autophagy has been described in alveolar epithelial cells (AEC) to cope with the progression of pulmonary fibrosis. Hence, this study is to investigate the effects of leptin on fibrosis in TGF-β1 induced epithelial mesenchymal transition (EMT) and the potential roles of autophagy in this processes. Our results showed that the elevated leptin level in serum correlated with the severity of lung fibrosis and leptin significantly promoted the EMT in A549 cells as evidenced by promoting collagen I and α-SMA production. Additionally, treatment with leptin decreased autophagosome formation, inhibited the lipidation of LC3I to LC3II, and up-regulated the expression of p62 via activating PI3K/Akt/mTOR pathway, which is indicative of inhibition of autophagy by leptin. Finally, rapmycin pretreatment reversed the pro-fibrogenic effects of leptin. Taken together, our study suggested that leptin accelerated the EMT of A549 cells through inhibiting autophagy via PI3K/Akt/mTOR pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

MicroRNA-155 inversely correlates with esophageal cancer progression through regulating tumor-associated macrophage FGF2 expression

Highlights: • miR-155 and FGF2 is associated with esophageal cancer progression. • miR-155 in TAMs suppressed ECA109 cell proliferation, migration and invasion, as well as reduction in angiogenesis. • miR-155-reduced cell growth, migration and invasion of ECA109 cells is associated with FGF2 suppression. Esophageal cancer (EC) is one of the most common malignancies with high incidence and mortality. Tumor-associated macrophages (TAMs) in the tumor microenvironment have been linked to the accelerated tumor progression. MicroRNAs (miR) are 19–25 nucleotide-long, noncoding RNA molecules, functioning as modulators of gene expression, and mediate a variety of biological functions, including tumor growth. In the present study, the effects and molecular mechanism of miR-155 in TAMs isolated from EC were explored. The expression of miR-155 and fibroblast growth factor-2 (FGF2) in EC tissues and cell lines were analyzed using reverse transcription-quantitative PCR (qRT-PCR) and western blot assays. TAMs were also transfected with the described constructs. Following, the culture medium from TAMs was collected for further analysis. The released FGF2, and inflammatory cytokines were quantified using ELISA. The cell viability, migrated and invaded levels were calculated through Cell Counting kit-8 (CCK8), and transwell analysis. Moreover, human umbilical vein endothelial cells (HUVEC) vasculature formation was determined using matrigel angiogenesis analysis. The results indicated that miR-155 expression was decreased in EC tissues and cell lines, while FGF2 expression was increased in comparison to those in the normal control group. Moreover, miR-155 mimics transfection up-regulated tumor necrosis factor α (TNF-α), interleukin (IL)-12 and inducible nitric oxide synthase (iNOS), while down-regulated IL-10, Arginase-1 (Arg-1) and IL-22 levels in the culture medium from TAMs. And enhancing miR-155 expression in TAMs suppressed the cell viability, migration and invasion of ECA109 cells and reduced the angiogenesis. Nevertheless, over-expressing FGF2 abolished the role of miR-155 in cancer cell survival, migration, invasion as well as angiogenesis. Our findings indicated that miR-155-regulated FGF2 expression from TAMs suppressed EC cell proliferation, migration, invasion and inhibited vasculature formation. Thus, miR-155-modulated FGF2 might be a potential therapeutic target to prevent EC progression.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Long non-coding RNA EPIC1 promotes human lung cancer cell growth

Highlights: • Lnc-EPIC1 expression is elevated in human lung cancer cells and tissues. • Lnc-EPIC1 siRNA inhibits lung cancer cell growth, but inducing cell cycle arrest and apoptosis. • MYC is the primary target of Lnc-EPIC1 in lung cancer cells. • Lnc-EPIC1 overexpression promotes lung cancer cell growth. Long non-coding RNA (LncRNA) EPIC1 (Lnc-EPIC1) is a MYC-interacting LncRNA. In the present study, the expression and potential function of Lnc-EPIC1 in human lung cancer cells are tested. We show that Lnc-EPIC1 expression is significantly higher in established/primary human lung cancer cells than that in human lung epithelial cells. Lnc-EPIC1 is also elevated in human lung cancer tissues. Silencing of Lnc-EPIC1 by targeted siRNA significantly inhibited human lung cancer cell growth, survival and proliferation, whiling inducing G1-S cell cycle arrest and cell apoptosis. MYC targets, including Cyclin A1, CDC20 and CDC45, were downregulated by Lnc-EPIC1 siRNA. MYC knockout by CRISPR/Cas-9 gene-editing method mimicked actions by Lnc-EPIC1 siRNA in A549 cells. Conversely, forced overexpression of Lnc-EPIC1 by a lentiviral construct increased expression of MYC targets to promote A549 cell growth. Lnc-EPIC1 directly associated with MYC protein in the nuclei of A549 cells. Significantly MYC knockout abolished Lnc-EPIC1 silencing- or overexpression-induced actions in human lung cancer cells. Together, our results show that Lnc-EPIC1 promotes human lung cancer cell growth possibly by targeting MYC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

KPT-330, a potent and selective CRM1 inhibitor, exhibits anti-inflammation effects and protection against sepsis

Highlights: • KPT330 protects against LPS-induced septic mice. • KPT330 exerts anti-inflammation effects. • KPT330 inhibits LPS-induced TNF-α, IL-6 and HMGB1 production. • KPT330 suppresses activation of NF-κB and MAPK p38 signaling. Sepsis, a systemic inflammatory response caused by infection or injury, is still one of the most important causes of death in clinical patients. The ongoing search for the pathogenesis of sepsis and novel therapeutic methods are highly urgent. In this study, we hypothesized that KPT330, a potent and specific small molecule inhibitor of CRM1, could reduce inflammation and attenuate the severity of sepsis. In LPS-induced sepsis model in vivo, administration of KPT330 increased survival rate and ameliorated LPS-induced lung injury, with suppressed levels of TNF-α, IL-6 and HMGB1 in the circulation and decreased macrophage and PMN subpopulations in peritoneal cavity. In vitro investigations showed that KPT330 dose-dependently inhibited LPS-triggered proinflammatory cytokines production including TNF-α, IL-6 and HMGB1 in macrophages. Furthermore, KPT330 treatment significantly suppressed TNF-α and IL-6 mRNA expression and inhibited HMGB1 necleocytoplasmic translocation by inhibiting CRM1 distribution. Moreover, the mechanism analysis demonstrated that KPT330 exerted anti-inflammation effects by inhibiting the production of pro-inflammatory cytokines through suppressing activation of NF-κB and p38 signaling. Thus, pharmacologic stimulation of KPT330 may present a promising therapeutic strategy for sepsis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

All arthroscopic remnant-preserving reconstruction of the lateral ligaments of the ankle: A biomechanical study and clinical application

Highlights: • Two surgical techniques of ATFL and CFL reconstruction produce similar the strength and stiffness • The strength and stiffness of reconstructed ATFL and CFL are weaker than the intact, uninjured ATFL and CFL. • All arthroscopic remnant-preserving reconstruction of ATFL and CFL has good short-term clinical effect. Lateral ankle sprains are one of the most common injuries in sports. Recently, arthroscopic lateral ligament reconstruction has been recently advocated, however no biomechanical studies and clinical application of this technique are available. In this biomechanical study, eighteen fresh-frozen cadaveric ankles were randomized into three groups: (1) intact anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL), (2) arthroscopic anatomic reconstruction of ATFL and CFL, and (3) all arthroscopic remnant-preserving reconstruction of ATFL and CFL. The specimens were then tested for stiffness and load to ultimate failure using a customized jig. In biomechanical test, the all arthroscopic remnant-preserving reconstruction of ATFL and CFL produced a reconstruction that could withstand loads to failure and stiffness similar to the arthroscopic anatomic reconstruction. However, both two reconstruction groups were much weaker than the intact, uninjured ATFL and CFL. Moreover, we used the technique of all arthroscopic remnant-preserving reconstruction of ATFL and CFL on 20 patients from September 2016 to September 2017. American Orthopaedic Foot and Ankle Society (AOFAS) scores and Anterior Talar Translation (ATT) were applied for statistical collection at preoperative and postoperative 12 months to evaluate clinical efficacy. The differences of the preoperative and postoperative 12 months AOFAS scores and ATT of patients were both statistical significant (P < 0.01). We confirmed that all arthroscopic remnant-preserving reconstruction of ATFL and CFL exhibited positive effect, thus promoting the recovery of ankle function and had good short-term clinical effect.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Mutation network-based understanding of pleiotropic and epistatic mutational behavior of Enterococcus faecalis FMN-dependent azoreductase

We previously identified a highly active homodimeric FMN-dependent NADH-preferred azoreductase (AzoA) from Enterococcus faecalis, which cleaves the azo bonds (R-N = N-R) of diverse azo dyes, and determined its crystal structure. The preliminary network-based mutational analysis suggested that the two residues, Arg-21 and Asn121, have an apparent mutational potential for fine-tuning of AzoA, based on their beneficial pleiotropic feedbacks. However, epistasis between the two promising mutational spots in AzoA has not been obtained in terms of substrate binding and azoreductase activity. In this study, we further quantified, visualized, and described the pleiotropic and/or epistatic behavior of six single or double mutations at the positions, Arg-21 and Asn-121, as a further research endeavor for beneficial fine-tuning of AzoA. Based on this network-based mutational analysis, we showed that pleiotropy and epistasis are common, sensitive, and complex mutational behaviors, depending mainly on the structural and functional responsibility and the physicochemical properties of the residue(s) in AzoA.

Rational design↗