Search results for "protein structure"
showing 10 items of 757 documents
Bacterial sensor kinases using Fe–S cluster binding PAS or GAF domains for O2sensing
2012
[4Fe-4S](2+) clusters are used by very diverse types of bacterial sensors for response to oxygen, including DNA-binding proteins of the CRP/FNR family and sensor kinases like NreB. In NreB the cluster is bound by an input domain of the PAS type. The [4Fe-4S](2+) cluster of NreB responds to O(2) by degradation to a [2Fe-2S](2+) cluster which is labile and decomposes. NreB constitutes together with AirS the NreB/AirS family of bacterial sensor kinases that contain PAS or GAF domains for binding of [4Fe-4S](2+) or [2Fe-2S](2+) clusters and oxygen sensing. The NreB/AirS family is related to the FixL sensor kinases that use hemeB binding PAS domains for oxygen sensing.
Discovery of benzimidazole-based Leishmania mexicana cysteine protease CPB2.8ΔCTE inhibitors as potential therapeutics for leishmaniasis
2018
Abstract: Chemotherapy is currently the only effective approach to treat all forms of leishmaniasis. However, its effectiveness is severely limited due to high toxicity, long treatment length, drug resistance, or inadequate mode of administration. As a consequence, there is a need to identify new molecular scaffolds and targets as potential therapeutics for the treatment of this disease. We report a small series of 1,2‐substituted‐1H‐benzo[d]imidazole derivatives (9ad) showing affinity in the submicromolar range (Ki = 0.150.69 μM) toward Leishmania mexicanaCPB2.8ΔCTE, one of the more promising targets for antileishmanial drug design. The compounds confirmed activity in vitro against intrace…
D-Galactose binding lectins from the tunicate Ascidiamalaca: Subunit characterization and hemocyte surface distribution
1988
Abstract D-galactose specific lectins purified from Ascidia malaca serum contain a major protein component with an apparent molecular weight of about 58,000 daltons, which moves more rapidly under non-reducing conditions. Intramolecular disulfide linkages can explain this behaviour, suggesting a compact protein structure. Membrane lectins have been demonstrated on the surface of about 34% hemocytes by immunofluorescent methods using a rabbit antiserum against the isolated serum lectins. Small, medium and large hemocytes can be positive, as also shown by binding on Sepharose spherules or by rosette formation with sheep and rabbit erythrocytes. Binding is inhibited by the same sugars specific…
Nested allosteric interactions in extracellular hemoglobin of the leech Macrobdella decora
2003
Hemoglobin from the leech Macrobdella decora belongs to the class of giant extracellular hexagonal bilayer globin structures found in annelid and vestimentiferan worms. These complexes consist of 144 heme-bearing subunits, exhibit a characteristic quaternary structure (2 × (6 × (3 × 4))), and contain tetramers as basic substructures that express cooperative oxygen binding and thus provide a structural basis for a hierarchy in allosteric interactions. A thorough analysis of the isolated tetramer indicates that it functions as a trimer of cooperatively interacting subunits and a non-cooperative monomer rather than as four interacting subunits. A thermodynamic analysis of the whole molecule fa…
Hydrophobic mismatch of mobile transmembrane helices: Merging theory and experiments
2012
Abstract Hydrophobic mismatch still represents a puzzle for transmembrane peptides, despite the apparent simplicity of this concept and its demonstrated validity in natural membranes. Using a wealth of available experimental 2 H NMR data, we provide here a comprehensive explanation of the orientation and dynamics of model peptides in lipid bilayers, which shows how they can adapt to membranes of different thickness. The orientational adjustment of transmembrane α-helices can be understood as the result of a competition between the thermodynamically unfavorable lipid repacking associated with peptide tilting and the optimization of peptide/membrane hydrophobic coupling. In the positive misma…
Trehalose effects on α-crystallin aggregates
2007
alpha-Crystallin in its native state is a large, heterogeneous, low-molecular weight (LMW) aggregate that under certain conditions may progressively became part of insoluble high-molecular weight (HMW) systems. These systems are supposed to play a relevant role in eye lens opacification and vision impairment. In this paper, we report the effects of trehalose on alpha-crystallin aggregates. The role of trehalose in alpha-crystallin stress tolerance, chaperone activity and thermal stability is studied. The results show that trehalose stabilizes the alpha-crystallin native structure, inhibits alpha-crystallin aggregation, and disaggregates preformed LMW systems not affecting its chaperone acti…
Stitching proteins into membranes, not sew simple
2014
Abstract Most integral membrane proteins located within the endomembrane system of eukaryotic cells are first assembled co-translationally into the endoplasmic reticulum (ER) before being sorted and trafficked to other organelles. The assembly of membrane proteins is mediated by the ER translocon, which allows passage of lumenal domains through and lateral integration of transmembrane (TM) domains into the ER membrane. It may be convenient to imagine multi-TM domain containing membrane proteins being assembled by inserting their first TM domain in the correct orientation, with subsequent TM domains inserting with alternating orientations. However a simple threading model of assembly, with s…
Insertion and Topology of a Plant Viral Movement Protein in the Endoplasmic Reticulum Membrane
2002
Virus-encoded movement proteins (MPs) mediate cell-to-cell spread of viral RNA through plant membranous intercellular connections, the plasmodesmata. The molecular pathway by which MPs interact with viral genomes and target plasmodesmata channels is largely unknown. The 9-kDa MP from carnation mottle carmovirus (CarMV) contains two potential transmembrane domains. To explore the possibility that this protein is in fact an intrinsic membrane protein, we have investigated its insertion into the endoplasmic reticulum membrane. By using in vitro translation in the presence of dog pancreas microsomes, we demonstrate that CarMV p9 inserts into the endoplasmic reticulum without the aid of any addi…
Ionic self-complementarity induces amyloid-like fibril formation in an isolated domain of a plant copper metallochaperone protein
2004
This article is available from: http://www.biomedcentral.com/1472-6807/4/7
Cloning and characterization of Scavidin, a fusion protein for the targeted delivery of biotinylated molecules.
2001
We have constructed a novel fusion protein "Scavidin" consisting of the macrophage scavenger receptor class A and avidin. The Scavidin fusion protein is transported to plasma membranes where the avidin portion of the fusion protein binds biotin with high affinity and forms the basis for the targeted delivery of biotinylated molecules. Subcellular fractionation analysis, immunostaining, and electron microscopy demonstrated endosomal localization of the fusion protein. According to pulse-labeling and cross-linking studies Scavidin is found as monomers (55 kDa), dimers, and multimers, of which the 220-kDa form was the most abundant. The biotin binding capacity and active endocytosis of the bio…