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141.
Genetic locus encoding functions involved in biosynthesis and outer membrane localization of xanthomonadin in Xanthomonas oryzae pv. oryzae
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Xanthomonadins are membrane-bound, brominated, aryl-polyene pigments specific to the genus Xanthomonas. We have characterized a genetic locus (pig) from Xanthomonas oryzae pv. oryzae which contains four open reading frames (ORFs) that are essential for xanthomonadin production. Three of these ORFs are homologous to acyl carrier proteins, dehydratases, and acyl transferases, suggesting a type II polyketide synthase pathway for xanthomonadin biosynthesis. The fourth ORF has no homologue in the database. For the first time, we report that a putative cytoplasmic membrane protein encoded in the pig locus is required for outer membrane localization of xanthomonadin in X. oryzae pv. oryzae. We also report the identification of a novel 145-bp palindromic Xanthomonas repetitive intergenic consensus element that is present in two places in the pig locus. We estimate that more than 100 copies of this element might be present in the genome of X. oryzae pv. oryzae and other xanthomonads. 相似文献
142.
Methanol extracts of whole body (Melampus ceylonicus), blood (Anadara rhombea) and hepatopancreas (Sepiella inermis) were screened for antifungal and cytotoxic activity. Blood of A. rhombea and hepatopancreas of S. inermis strongly inhibited Candida albicans, Mucor racemosus and Penicillium expansum. A. rhombea appear to exert strong cytotoxic activity against vertebrate erythrocytes. The bacterial pathogens (Escherichia coli and Vibrio cholarae) were not inhibited by any of the three tested methanol extracts. 相似文献
143.
Huseyin Saribasak Deepa Rajagopal Robert W. Maul Patricia J. Gearhart 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2009,364(1517):605-611
Somatic hypermutation of immunoglobulin (Ig) genes occurs at a frequency that is a million times greater than the mutation in other genes. Mutations occur in variable genes to increase antibody affinity, and in switch regions before constant genes to cause switching from IgM to IgG. Hypermutation is initiated in activated B cells when the activation-induced deaminase protein deaminates cytosine in DNA to uracil. Uracils can be processed by either a mutagenic pathway to produce mutations or a non-mutagenic pathway to remove mutations. In the mutagenic pathway, we first studied the role of mismatch repair proteins, MSH2, MSH3, MSH6, PMS2 and MLH1, since they would recognize mismatches. The MSH2–MSH6 heterodimer is involved in hypermutation by binding to U:G and other mismatches generated during repair synthesis, but the other proteins are not necessary. Second, we analysed the role of low-fidelity DNA polymerases η, ι and θ in synthesizing mutations, and conclude that polymerase η is the dominant participant by generating mutations at A:T base pairs. In the non-mutagenic pathway, we examined the role of the Cockayne syndrome B protein that interacts with other repair proteins. Mice deficient in this protein had normal hypermutation and class switch recombination, showing that it is not involved. 相似文献
144.
Velamoor Rajagopal 《Physiologia plantarum》1981,52(2):292-296
Both the upper and lower stomata of Vicia faba responded to different concentrations of proline supplied either to the 'detached' leaves or sprayed to 'intact' leaves. The stomatal resistance of abaxial surfaces was increased more than that of the adaxial surfaces. A 1-h treatment with 5 m M proline had greater influence than a prolonged treatment. The 'young' leaves responded more than the 'mature' ones to the exogenous proline. A relationship could be demonstrated between endogenous proline, which increased markedly due to exogenous supply, and stomatal resistance. 相似文献
145.
Bacterial endosymbionts have been associated with arthropods and large number of the insect species show interaction with such bacteria. Different approaches have been used to understand such symbiont- host interactions. The whitefly, Bemisia tabaci, a highly invasive agricultural pest, harbors as many as seven different bacterial endosymbionts. These bacterial endosymbionts are known to provide various nutritional, physiological, environmental and evolutionary benefits to its insect host. In this study, we have tried to compare two techniques, Polymerase chain reaction (PCR) and Flourescence in situ Hybridisation (FISH) commonly used for identification and localization of bacterial endosymbionts in B. tabaci as it harbors one of the highest numbers of endosymbionts which have helped it in becoming a successful global invasive agricultural pest. The amplified PCR products were observed as bands on agarose gel by electrophoresis while the FISH samples were mounted on slides and observed under confocal microscope. Analysis of results obtained by these two techniques revealed the advantages of FISH over PCR. On a short note, performing FISH, using LNA probes proved to be more sensitive and informative for identification as well as localization of bacterial endosymbionts in B. tabaci than relying on PCR. This study would help in designing more efficient experiments based on much reliable detection procedure and studying the role of endosymbionts in insects. 相似文献
146.
Kodru Sireesha Malavath Tirupathi Devadasu Elsinraju Nellaepalli Sreedhar Stirbet Alexandrina Subramanyam Rajagopal Govindjee 《Photosynthesis research》2015,125(1-2):219-231
Photosynthesis Research - The green alga Chlamydomonas (C.) reinhardtii is a model organism for photosynthesis research. State transitions regulate redistribution of excitation energy between... 相似文献
147.
148.
Jeroen P. Vanderhoeven Craig J. Bierle Raj P. Kapur Ryan M. McAdams Richard P. Beyer Theo K. Bammler Federico M. Farin Aasthaa Bansal Min Spencer Mei Deng Michael G. Gravett Craig E. Rubens Lakshmi Rajagopal Kristina M. Adams Waldorf 《PLoS pathogens》2014,10(3)
Early events leading to intrauterine infection remain poorly defined, but may hold the key to preventing preterm delivery. To determine molecular pathways within fetal membranes (chorioamnion) associated with early choriodecidual infection that may progress to preterm premature rupture of membranes (PPROM), we examined the effects of a Group B Streptococcus (GBS) choriodecidual infection on chorioamnion in a nonhuman primate model. Ten chronically catheterized pregnant monkeys (Macaca nemestrina) at 118–125 days gestation (term = 172 days) received choriodecidual inoculation of either GBS (n = 5) or saline (n = 5). Cesarean section was performed in the first week after GBS or saline inoculation. RNA extracted from chorioamnion (inoculation site) was profiled by microarray. Single gene, Gene Set, and Ingenuity Pathway Analysis results were validated using qRT-PCR (chorioamnion), Luminex (amniotic fluid, AF), immunohistochemistry, and transmission electron microscopy (TEM). Despite uterine quiescence in most cases, significant elevations of AF cytokines (TNF-α, IL-8, IL-1β, IL-6) were detected in GBS versus controls (p<0.05). Choriodecidual infection resolved by the time of cesarean section in 3 of 5 cases and GBS was undetectable by culture and PCR in the AF. A total of 331 genes were differentially expressed (>2-fold change, p<0.05). Remarkably, GBS exposure was associated with significantly downregulated expression of multiple cytokeratin (CK) and other cytoskeletal genes critical for maintenance of tissue tensile strength. Immunofluorescence revealed highly significant changes in the CK network within amniocytes with dense CK aggregates and retraction from the cell periphery (all p = 0.006). In human pregnancies affected by PPROM, there was further evidence of CK network retraction with significantly shorter amniocyte foot processes (p = 0.002). These results suggest early choriodecidual infection results in decreased cellular membrane integrity and tensile strength via dysfunction of CK networks. Downregulation of CK expression and perturbations in the amniotic epithelial cell intermediate filament network occur after GBS choriodecidual infection, which may contribute to PPROM. 相似文献
149.
Kahsai AW Xiao K Rajagopal S Ahn S Shukla AK Sun J Oas TG Lefkowitz RJ 《Nature chemical biology》2011,7(10):692-700
Seven-transmembrane receptors (7TMRs), also called G protein-coupled receptors (GPCRs), represent the largest class of drug targets, and they can signal through several distinct mechanisms including those mediated by G proteins and the multifunctional adaptor proteins β-arrestins. Moreover, several receptor ligands with differential efficacies toward these distinct signaling pathways have been identified. However, the structural basis and mechanism underlying this 'biased agonism' remains largely unknown. Here, we develop a quantitative mass spectrometry strategy that measures specific reactivities of individual side chains to investigate dynamic conformational changes in the β(2)-adrenergic receptor occupied by nine functionally distinct ligands. Unexpectedly, only a minority of residues showed reactivity patterns consistent with classical agonism, whereas the majority showed distinct patterns of reactivity even between functionally similar ligands. These findings demonstrate, contrary to two-state models for receptor activity, that there is significant variability in receptor conformations induced by different ligands, which has significant implications for the design of new therapeutic agents. 相似文献
150.
Ferit Tuzer Navid Madani Kantharaju Kamanna Isaac Zentner Judith LaLonde Andrew Holmes Elizabeth Upton Srivats Rajagopal Karyn McFadden Mark Contarino Joseph Sodroski Irwin Chaiken 《Proteins》2013,81(2):271-290
Despite advances in HIV therapy, viral resistance and side‐effects with current drug regimens require targeting new components of the virus. Dual antagonist peptide triazoles (PT) are a novel class of HIV‐1 inhibitors that specifically target the gp120 component of the viral spike and inhibit its interaction with both of its cell surface protein ligands, namely the initial receptor CD4 and the co‐receptor (CCR5/CXCR4), thus preventing viral entry. Following an initial survey of 19 gp120 alanine mutants by ELISA, we screened 11 mutants for their importance in binding to, and inhibition by the PT KR21 using surface plasmon resonance. Key mutants were purified and tested for their effects on the peptide's affinity and its ability to inhibit binding of CD4 and the co‐receptor surrogate mAb 17b. Effects of the mutations on KR21 viral neutralization were measured by single‐round cell infection assays. Two mutations, D474A and T257A, caused large‐scale loss of KR21 binding, as well as losses in both CD4/17b and viral inhibition by KR21. A set of other Ala mutants revealed more moderate losses in direct binding affinity and inhibition sensitivity to KR21. The cluster of sensitive residues defines a PT functional epitope. This site is in a conserved region of gp120 that overlaps the CD4 binding site and is distant from the co‐receptor/17b binding site, suggesting an allosteric mode of inhibition for the latter. The arrangement and sequence conservation of the residues in the functional epitope explain the breadth of antiviral activity, and improve the potential for rational inhibitor development. Proteins 2013. © 2012 Wiley Periodicals, Inc. 相似文献