A three-dimensional model of the PsbS protein was built with the help of homology-modeling methods. This protein is also known as CP22 and is associated with the protection of photosystem II of thylakoid from excess quanta of light energy absorbed by the photosynthetic apparatus. PsbS is reported to bind two molecules of zeaxanthin at low pH (<5.0) and is believed to be essential for rapid nonphotochemical quenching (qE) of chlorophyll a fluorescence in photosystem II. An attempt was made to explain the pH modulation of the conformation of protein through salt-bridges Glu−(122)-Lys+(113) and Glu−(226)-Lys+(217). Binding of two molecules of zeaxanthin in the three-dimensional model of PsbS is postulated. The molecular mechanism of photoprotection by PsbS is explained through the model.
1 Backbone structure of the PsbS protein with two molecules of all trans zeaxanthin (ZEX). Residues Glu 90, 122, 194, 226 and Lys 113, 217 are shown. The figure is drawn with RASMOL (Molecular Visualization Program, RasMol V2.6, Roger Sayle, Glaxo Wellcome Research and Development, Stevenage, Hertfordshire, UK)
Electronic Supplementary Material Supplementary material is available for this article at 相似文献
Flooding stress (FS) induced changes in pigment and protein contents and in photochemical efficiency of thylakoid membranes
of chloroplasts were investigated during senescence of primary leaves of rice seedlings. Leaf senescence was accompanied by
loss in 2,6-dichlorophenolindophenol (DCPIP) photoreduction, rate of oxygen evolution, quantum yield of photosystem 2 with
an increase in MDA accumulation, and non-photochemical quenching (NPQ) of chlorophyll fluorescence. These changes were further
aggravated when the leaves during this period experienced FS. The increase in NPQ value under stress may indicate photosynthetic
adaptation to FS. 相似文献
To determine whether the G–H loop of foot-and-mouth disease virus (FMDV) serotype O can function as a target structure to harbour and display serotype Asia1 antigenic epitope at the surface.
Results
Using reverse genetics, FMDV serotype O IND R2/1975 displaying a FMDV serotype Asia1 B cell epitope at the capsid surface was constructed. The epitope-inserted recombinant chimeric virus was genetically stable up to ten serial passages in cell culture and exhibited growth properties similar to the parental serotype O virus. Furthermore, the surface-displayed Asia1 epitope able to react with serotype Asia1 specific antibodies in a competitive ELISA. Importantly, the recombinant chimeric virus showed neutralizing activity to both serotype O and Asia1 polyclonal antibodies.
Conclusion
The capsid protein of FMDV serotype O can effectively display potent epitope of other serotypes, making this an attractive approach for the design of new generation bi-valent FMD vaccines.
Plectranthus amboinicus (Lour.) Spreng, known as the Indian borage or Mexican mint, is one of the most documented species in the family Lamiaceae for its therapeutic and pharmaceutical values. It is found in the tropical and subtropical regions of the world. The leaf essential oil has immense medicinal benefits like treating illnesses of the skin and disorders like colds, asthma, constipation, headaches, coughs, and fevers. After analyzing earlier reports with regard to the quantity and quality of leaf oil yield, we discovered that the germplasm taken from Odisha is preferable to other germplasms. The objective of the present work is to evaluate the free radical scavenging activity and bactericidal effect of leaf essential oil (EO) of Plectranthus amboinicus (Lour.) Spreng collected from the state of Odisha, India. The hydro distillation technique has been used for essential oil extraction. Upon GC/MS analysis, approximately 57 compounds were identified with Carvacrol as the major compound (peak area=20.25 %), followed by p-thymol (peak area=20.17 %), o-cymene (peak area=19.41 %) and carene (peak area=15.89 %). On evaluation of free radical scavenging activity, it was recorded that the best value of inhibitory concentration, was for DPPH with IC50=18.64 ppm and for H2O2 with IC50=9.35 ppm. The EO showed efficient bactericidal effect against both gram positive (Mycobacterium smegmatis, Staphylococcus aureus, Enterococcus faecium) and gram negative (Escherichia coli, Vibrio cholerae, Klebsiella pneumoniae) bacteria studied through well diffusion method. Fumigatory action of the essential oil was found against M. smegmatis, the model organism for tuberculosis study. Alamar Blue assay, gave a result with MIC value for M. smegmatis i. e., 0.12 μg/ml and the MBC value of 0.12 μg/ml. Hence, P. amboinicus found in Odisha can be suggested as an elite variety and should be further investigated for efficient administration in drug formulation. 相似文献
Radionuclide contamination is a concerning threat due to unexpected nuclear disasters and authorized discharge of radioactive elements, both in the past and in present times. Use of atomic power for energy generation is associated with unresolved issues concerning storage of residues and contaminants. For example, the nuclear accidents in Chernobyl 1986 and Fukushima 2011 resulted in considerable deposition of cesium (Cs) in soil, along with other radionuclides. Among Cs radioactive variants, the anthropogenic radioisotope 137Cs (t½?=?30.16 years) is of serious environmental concern, owing to its rapid incorporation into biological systems and emission of β and γ radiation during the decaying process. To remediate contaminated areas, mostly conventional techniques are applied that are not eco-friendly. Hence, an alternative green technology, i.e., phytoremediation, should in future be considered and implemented. This sustainable technology generates limited secondary waste and its objectives are to utilize hyper-accumulating plants to extract, stabilize, degrade, and filter the radionuclides. The review highlights plant mechanisms for up-taking radionuclides and influences of different environmental factors involved in the process, while considering its long-term effects.
Summary The following properties of the DNA of B. subtilis phage SP50 were established: Molecular weight (in Daltons) 102×106 (sedimentation velocity) 97×106 (viscosity) 97×106 (contour lengths of electron micrographs) Base Composition (in % GC) 41.7 (chemical analysis) 44 (melting point) 44 (buoyant density) No unusual bases were observed. The complementary strands of the DNA can be separated. The phage DNA has genuine single strand breaks. The number and distribution of such breaks appears to be determined by the host on which phages were grown.This investigation was supported in part by a Public Health Service research grant GM 13,666 from the National Institutes of General Medical Sciences, AI 01267 from the National Institutes of Allergy and Infectious Diseases, AM 04763 from the National Institutes of Arthritis and Metabolic Diseases; cancer research funds from the University of California; and a grant from the Hartford Foundation. 相似文献
Aging of cell-free chloroplasts at pH 7.0 and 9.0 causes a decline in the level of photosynthetic pigments, quenching of chlorophyll a fluorescence and enhancement in fluorescence polarization. These changes are correlated with photoinduced enhancement of thylakoid lipid peroxidation. The alkaline earth metal cations, namely magnesium and calcium, show opposite actions on lipid peroxidation and modulate thylakoid disorganisation differently. Magnesium ion may stabilise thylakoid membrane by retarding lipid peroxidation. It lowers aging-induced quenching of fluorescence intensity and enhancement of fluorescence polarization. Calcium ion, on the other hand, stimulates disorganisation of thylakoid membranes. It enhances membrane lipid peroxidation, quenching of chlorophyll a fluorescence intensity and fluorescence polarization. 相似文献
Connexin43 (Cx43) is a member of the family of channel-forming proteins that make up the gap junction and are believed to provide pathways for cell-cell exchange of developmental signals. We have used immunofluorescence and confocal microscopy to characterize the patterns of distribution of Cx43 in postimplantation mouse embryos representing stages of development extending through gastrulation and the major period of organogenesis [through 13.5 days post coitum (dpc)]. We find that Cx43 is expressed early after implantation by the undifferentiated, pluripotent cells of the primitive embryonic ectoderm from which all tissues of the fetus are believed to be derived. As cells become committed to particular developmental pathways, there is a progressive restriction of Cx43 to specific areas and organ systems. The patterns are complex and not limited by germ layer of origin, although there is a clear preference for expression in ectodermal and, to a lesser extent, mesodermal derivatives. Expression in lens, retina, kidney, brain, pineal and pituitary glands is initiated early in organogenesis. In heart, the first clear signal for Cx43 appears in the ventricle at about 10 dpc and is only subsequently detected in the atrium at about 13-13.5 dpc. Particularly intriguing with regard to functional implications is the high level expression observed at sites of inductive interaction; the eye lens and optic cup, the infundibulum and the apical ectodermal ridge of the limb bud. 相似文献