Protein-protein interactions have been regarded as "undruggable" despite their importance in many biological processes. The complex formed between host toll-like receptor 5 (TLR5) and flagellin, a globular protein that is the main component of a bacterial flagellum, plays a vital role in a number of pathogen defenses, immunological diseases and cancers. Through high-throughput screening, we identified two hits with a common pharmacophore, which were used to successfully develop a series of small-molecule probes as novel inhibitors of flagellin binding to TLR5. In a multitude of assays, 4-((4-benzyl-5-(pyridin4yl)-4H-1,2,4-triazol-3-yl)thio)pyrido[3',2':4,5]thieno[3,2-d]pyrimidine (TH1020) was identified as a potent antagonist of TLR5 signaling with promising activity (IC50 =0.85±0.12 μm) and specificity. Furthermore, TH1020 was shown to repress the expression of downstream TNF-α signaling pathways mediated by the TLR5/flagellin complex formation. Based on molecular docking simulation, TH1020 is suggested to compete with flagellin and disrupt its association with TLR5. TH1020 provides a much-needed molecular probe for studying this important protein-protein interaction and a lead compound for identifying novel therapeutics targeting TLR5.
In order to get a better understanding of protein association during Solanum tuberosum (cv. Sarpo Mira)–Phytophthora infestans incompatible interaction, we investigated the proteome dynamics of cv. Sarpo Mira, after foliar application of zoospore suspension from P. infestans isolate, at three key time-points: zero hours post inoculation (hpi) (Control), 48 hpi (EI), and 120 hpi (LI); divided into early and late disease stages by the tandem mass tagging (TMT) method. A total of 1229 differentially-expressed proteins (DEPs) were identified in cv. Sarpo Mira in a pairwise comparison of the two disease stages, including commonly shared DEPs, specific DEPs in early and late disease stages, respectively. Over 80% of the changes in protein abundance were up-regulated in the early stages of infection, whereas more DEPs (61%) were down-regulated in the later disease stage. Expression patterns, functional category, and enrichment tests highlighted significant coordination and enrichment of cell wall-associated defense response proteins during the early stage of infection. The late stage was characterized by a cellular protein modification process, membrane protein complex formation, and cell death induction. These results, together with phenotypic observations, provide further insight into the molecular mechanism of P. infestans resistance in potatos.
Membrane curvature and lipid composition plays critical role in interchanging of matter and energy in cells. Peptide curvature sensors are known to activate signaling pathways, and promote molecular transport across cell membranes. Recently, the 25-mer MARCKS-ED peptide, which is derived from the effector domain of the myristoylated alanine-rich C kinase substrate protein, has been reported to selectively recognize highly curved membrane surfaces. Our previous studies indicated that the naturally occurring L-MARCKS-ED peptide could simultaneously detect both phosphatidylserine (PS) and curvature. Here, we demonstrate that D-MARCKS-ED, composed by unnatural D-amino acids, has the same activities as its enantiomer, LMARCKS-ED, as a curvature and lipid sensor. An atomistic molecular dynamics (MD) simulation suggests that D-MARCKS-ED may change from linear to a boat conformation upon binding to the membrane. Comparable enhancement of fluorescence intensity was observed between D- and L- MARCKS-ED peptides, indicating similar binding affinities. Meanwhile, circular dichroism (CD) spectra of D- and L- MARCKS-ED are almost symmetrical both in the presence and absence of liposomes. These results suggest similar behavior of artificial D- and natural L- MARCKS-ED peptides when binding to curved membranes. Our studies may contribute to further understanding of how MARCKS-ED senses membrane curvature, as well as provide a new direction to develop novel membrane curvature probes.
Background
Endotracheal intubation is known to pose significant physiological, pharmacokinetic, and dynamic changes and postoperative respiratory complications in patients under general anesthesia.
Method
An RCT trial was organized by the Third Affiliated Hospital at Sun Yat-sen University, China. Patients were eligible for inclusion in the trial if they were over 60 years old and had upper-abdominal surgery during the induction of anesthesia and had enrolled in endotracheal intubations. The primary end point included cardiovascular reactions during the induction of anesthesia and endotracheal intubations and cough events during the recovery period. In the test group, 2 g of lidocaine/prilocaine cream (and in the control group, 2 g of Vaseline) were laid over the surface of the tracheal tube cuff.
Results
The systolic blood pressure (F value = 62.271, p < 0.001), diastolic blood pressure (F value = 150.875, p < 0.001), and heart rate (F value = 75.627, p < 0.001) of the test group were significantly lower than the control group. Cough events during the recovery period in the test group were better (spontaneous cough, χ2 value = 10.591, p < 0.001; induced cough, χ2 value =10.806, p < 0.001).
Conclusion
In older patients, coughing and cardiovascular reactions under anesthesia and endotracheal intubations were reduced, as a result of using lidocaine/prilocaine cream on the surface of the tracheal tube cuff.
Trial registration
International Clinical Trials Network NCT02017392, 2013-12-16.
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