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An incoherent feed‐forward loop mediates robustness and tunability in a plant immune network
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Akira Mine Thomas M Winkelmüller Shajahan Anver Dieter Becker Kenichi Tsuda 《EMBO reports》2017,18(3):464-476
Immune signaling networks must be tunable to alleviate fitness costs associated with immunity and, at the same time, robust against pathogen interferences. How these properties mechanistically emerge in plant immune signaling networks is poorly understood. Here, we discovered a molecular mechanism by which the model plant species Arabidopsis thaliana achieves robust and tunable immunity triggered by the microbe‐associated molecular pattern, flg22. Salicylic acid (SA) is a major plant immune signal molecule. Another signal molecule jasmonate (JA) induced expression of a gene essential for SA accumulation, EDS5. Paradoxically, JA inhibited expression of PAD4, a positive regulator of EDS5 expression. This incoherent type‐4 feed‐forward loop (I4‐FFL) enabled JA to mitigate SA accumulation in the intact network but to support it under perturbation of PAD4, thereby minimizing the negative impact of SA on fitness as well as conferring robust SA‐mediated immunity. We also present evidence for evolutionary conservation of these gene regulations in the family Brassicaceae. Our results highlight an I4‐FFL that simultaneously provides the immune network with robustness and tunability in A. thaliana and possibly in its relatives. 相似文献
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Sithara Venkateshwar M. Moses Ambroise G. Johny Asir Nagaraja Mudhigeti Anita Ramdas K. Authy M. R. Shivaprakash Reba Kanungo 《Mycopathologia》2014,178(1-2):117-121
We report a rare case of phaeohyphomycotic cyst in an immunocompetent patient caused by Exophiala oligosperma. This fungus is earlier known to cause infections in the immunocompromised. Identification of black fungi at species level is more challenging by conventional methods, and hence final identification of the fungi was based on sequencing of rDNA. The patient was managed with surgical excision. To the best of our knowledge, this is the first case report of E. oligosperma human infection from India. 相似文献
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Amanda Haymond Chinchu Johny Tyrone Dowdy Brandon Schweibenz Karen Villarroel Richard Young Clark J. Mantooth Trishal Patel Jessica Bases Geraldine San Jose Emily R. Jackson Cynthia S. Dowd Robin D. Couch 《PloS one》2014,9(8)
The methylerythritol phosphate (MEP) pathway found in many bacteria governs the synthesis of isoprenoids, which are crucial lipid precursors for vital cell components such as ubiquinone. Because mammals synthesize isoprenoids via an alternate pathway, the bacterial MEP pathway is an attractive target for novel antibiotic development, necessitated by emerging antibiotic resistance as well as biodefense concerns. The first committed step in the MEP pathway is the reduction and isomerization of 1-deoxy-D-xylulose-5-phosphate (DXP) to methylerythritol phosphate (MEP), catalyzed by MEP synthase. To facilitate drug development, we cloned, expressed, purified, and characterized MEP synthase from Yersinia pestis. Enzyme assays indicate apparent kinetic constants of KM
DXP = 252 µM and KM
NADPH = 13 µM, IC50 values for fosmidomycin and FR900098 of 710 nM and 231 nM respectively, and Ki values for fosmidomycin and FR900098 of 251 nM and 101 nM respectively. To ascertain if the Y. pestis MEP synthase was amenable to a high-throughput screening campaign, the Z-factor was determined (0.9) then the purified enzyme was screened against a pilot scale library containing rationally designed fosmidomycin analogs and natural product extracts. Several hit molecules were obtained, most notably a natural product allosteric affector of MEP synthase and a rationally designed bisubstrate derivative of FR900098 (able to associate with both the NADPH and DXP binding sites in MEP synthase). It is particularly noteworthy that allosteric regulation of MEP synthase has not been described previously. Thus, our discovery implicates an alternative site (and new chemical space) for rational drug development. 相似文献
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V.T.P. Vinod R.B. Sashidhar B. Sreedhar B. Rama Rao T. Nageswara Rao Johny T. Abraham 《Carbohydrate polymers》2009,78(4):894-901
Gum kondagogu (Cochlospermum gossypium), an exudates tree gum from India was explored for its potential to decontaminate toxic metals (Pb2+ and Cd2+). Optimum biosorption of metals were determined by investigating the contact time, pH, initial concentration of metal ions and biosorbent dose at 25 ± 2 °C. The maximum metal biosorption capacity for gum kondagogu was observed for Pb2+ (48.52 mg g−1) and Cd2+ (47.48 mg g−1) as calculated by Langmuir isotherm model. Kinetic studies showed that the biosorption rates could be described by pseudo-second-order expression. The metal interactions with biopolymer were assessed by FT-IR, SEM–EDXA and XPS analysis. Results based on these techniques suggest that mechanism of metal binding by the biopolymer involves micro-precipitation, ion-exchange and metal complexation. 相似文献
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