Search results for "binding"
showing 10 items of 3896 documents
Formation and trapping of the thermodynamically unfavoured inverted-hemicucurbit[6]uril
2019
Amplification of a thermodynamically unfavoured macrocyclic product through the directed shift of the equilibrium between dynamic covalent chemistry library members is difficult to achieve. We show for the first time that during condensation of formaldehyde and cis-N,N'-cyclohexa-1,2-diylurea formation of inverted-cis-cyclohexanohemicucurbit[6]uril (i-cis-cycHC[6]) can be induced at the expense of thermodynamically favoured cis-cyclohexanohemicucurbit[6]uril (cis-cycHC[6]). The formation of i-cis-cycHC[6] is enhanced in low concentration of the templating chloride anion and suppressed in excess of this template. We found that reaction selectivity is governed by the solution-based template-a…
Metal Complexes of Two Specific Regions of ZnuA, a Periplasmic Zinc(II) Transporter from Escherichia coli
2020
The crystal structure of ZnZnuA from Escherichia coli reveals two metal binding sites. (i) The primary binding site, His143, is located close the His-rich loop (residues 116-138) and plays a significant role in Zn(II) acquisition. (ii) The secondary binding site involves His224. In this work, we focus on understanding the interactions of two metal ions, Zn(II) and Cu(II), with two regions of ZnuA, which are possible anchoring sites for Zn(II): Ac-115MKSIHGDDDDHDHAEKSDEDHHHGDFNMHLW145-NH2 (primary metal binding site) and Ac-223GHFTVNPEIQPGAQRLHE240-NH2 (secondary metal binding site). The histidine-rich loop (residues 116-138) has a role in the capture of zinc(II), which is then further deliv…
Specific binding of Bacillus thuringiensis Cry1Ea toxin, and Cry1Ac and Cry1Fa competition analyses in Anticarsia gemmatalis and Chrysodeixis include…
2019
AbstractAnticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper) are two important defoliation pests of soybeans. In the present study, we have investigated the susceptibility and brush border membrane-binding properties of both species to Bacillus thuringiensis Cry1Ea toxin. Bioassays performed in first-instar larvae demonstrated potent activity against both soybean pests in terms of mortality or practical mortality. Competition-binding studies carried out with 125Iodine-labelled Cry1Ea, demonstrated the presence of specific binding sites on the midgut brush border membrane vesicles (BBMV) of both insect species. Heterologous competition-binding experiment…
Role of Bacillus thuringiensis Cry1A toxins domains in the binding to the ABCC2 receptor from Spodoptera exigua
2018
Abstract Cry proteins from Bacillus thuringiensis (Bt) have been used to control insect pests either as formulated sprays or as in Bt-crops. However, field-evolved resistance to Bt proteins is threatening the long-term use of Bt products. The SeABCC2 locus has been genetically linked to resistance to a Bt bioinsecticide (Xentari™) in Spodoptera exigua (a mutation producing a truncated form of the transporter lacking an ATP binding domain was found in the resistant insects). Here, we investigated the role of SeABCC2 in the mode of action of Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ca, and two Cry1A-1Ca hybrids by expressing the receptor in Sf21 and HEK293T cell lines. Cell toxicity assays showed that Sf2…
How water-soluble chlorophyll protein extracts chlorophyll from membranes.
2020
Water-soluble chlorophyll proteins (WSCPs) found in Brassicaceae are non-photosynthetic proteins that bind only a small number of chlorophylls. Their biological function remains unclear, but recent data indicate that WSCPs are involved in stress response and pathogen defense as producers of reactive oxygen species and/or Chl-regulated protease inhibitors. For those functions, WSCP apoprotein supposedly binds Chl to become physiologically active or inactive, respectively. Thus, Chl-binding seems to be a pivotal step for the biological function of WSCP. WSCP can extract Chl from the thylakoid membrane but little is known about the mechanism of how Chl is sequestered from the membrane into the…
Daily rhythmicity of high affinity copper transport
2016
A differential demand for copper (Cu) of essential cupro-proteins that act within the mitochondrial and chloroplastal electronic transport chains occurs along the daily light/dark cycles. This requires a fine-tuned spatiotemporal regulation of Cu delivery, becoming especially relevant under non-optimal growth conditions. When scarce, Cu is imported through plasma membrane-bound high affinity Cu transporters (COPTs) whose coding genes are transcriptionally induced by the SPL7 transcription factor. Temporal homeostatic mechanisms are evidenced by the presence of multiple light- and clock-responsive regulatory cis elements in the promoters of both SPL7 and its COPT targets. A model is presente…
Characterization of the resistance to Vip3Aa in Helicoverpa armigera from Australia and the role of midgut processing and receptor binding.
2016
AbstractCrops expressing genes from Bacillus thuringiensis (Bt crops) are among the most successful technologies developed for the control of pests but the evolution of resistance to them remains a challenge. Insect resistant cotton and maize expressing the Bt Vip3Aa protein were recently commercialized, though not yet in Australia. We found that, although relatively high, the frequency of alleles for resistance to Vip3Aa in field populations of H. armigera in Australia did not increase over the past four seasons until 2014/15. Three new isofemale lines were determined to be allelic with previously isolated lines, suggesting that they belong to one common gene and this mechanism is relative…
Identification of Stress Associated microRNAs in Solanum lycopersicum by High-Throughput Sequencing
2019
Tomato (Solanum lycopersicum) is one of the most important crops around the world and also a model plant to study response to stress. High-throughput sequencing was used to analyse the microRNA (miRNA) profile of tomato plants undergoing five biotic and abiotic stress conditions (drought, heat, P. syringae infection, B. cinerea infection, and herbivore insect attack with Leptinotarsa decemlineata larvae) and one chemical treatment with a plant defence inducer, hexanoic acid. We identified 104 conserved miRNAs belonging to 37 families and we predicted 61 novel tomato miRNAs. Among those 165 miRNAs, 41 were stress-responsive. Reverse transcription quantitative PCR (RT-qPCR) was used to valida…
Acceptor Specificity of Amylosucrase from Deinococcus radiopugnans and Its Application for Synthesis of Rutin Derivatives
2016
The transglycosylation activity of amylosucrase (ASase) has received significant attention owing to its use of an inexpensive donor, sucrose, and broad acceptor specificity, including glycone and aglycone compounds. The transglycosylation reaction of recombinant ASase from Deinococcus radiopugnans (DRpAS) was investigated using various phenolic compounds, and quercetin-3-O-rutinoside (rutin) was found to be the most suitable acceptor molecule used by DRpAS. Two amino acid residues in DRpAS variants (DRpAS Q299K and DRpAS Q299R), assumed to be involved in acceptor binding, were constructed by site-directed mutagenesis. Intriguingly, DRpAS Q299K and DRpAS Q299R produced 10-fold and 4-fold hig…
The Odorant-Binding Proteins of the Spider Mite Tetranychus urticae
2021
Spider mites are one of the major agricultural pests, feeding on a large variety of plants. As a contribution to understanding chemical communication in these arthropods, we have characterized a recently discovered class of odorant-binding proteins (OBPs) in Tetranychus urticae. As in other species of Chelicerata, the four OBPs of T. urticae contain six conserved cysteines paired in a pattern (C1–C6, C2–C3, C4–C5) differing from that of insect counterparts (C1–C3, C2–C5, C4–C6). Proteomic analysis uncovered a second family of OBPs, including twelve members that are likely to be unique to T. urticae. A three-dimensional model of TurtOBP1, built on the recent X-ray structure of Varroa destruc…