Search results for " Tertiary"
showing 10 items of 349 documents
Light-induced Changes in the Dimerization Interface of Bacteriophytochromes
2015
Phytochromes are dimeric photoreceptor proteins that sense red light levels in plants, fungi, and bacteria. The proteins are structurally divided into a light-sensing photosensory module consisting of PAS, GAF, and PHY domains and a signaling output module, which in bacteriophytochromes typically is a histidine kinase (HK) domain. Existing structural data suggest that two dimerization interfaces exist between the GAF and HK domains, but their functional roles remain unclear. Using mutational, biochemical, and computational analyses of the Deinococcus radiodurans phytochrome, we demonstrate that two dimerization interfaces between sister GAF and HK domains stabilize the dimer with approximat…
Sponge Bcl-2 homologous protein (BHP2-GC) confers distinct stress resistance to human HEK-293 cells
2001
It is established that sponges, the phylogenetically oldest still extant phylum of Metazoa, possess key molecules of the apoptotic pathways, that is members from the Bcl-2 family and a pro-apoptotic molecule with death domains. Here we report on transfection studies of human cells with a sponge gene, GCBHP2. Sponge tissue was exposed to heat shock and tributyltin, which caused an upregulation of gene expression of GCBHP2. The cDNA GCBHP2 was introduced into human HEK-293 cells and mouse NIH-3T3 cells; the stable transfection was confirmed by the identification of the transcripts, by Western blotting as well as by immunofluorescence using antibodies raised against the recombinant polypeptide…
Nouvelles perspectives concernant la structure et la fonction du domaine carboxyl terminal de Hfq
2015
Accumulating evidence indicates that RNA metabolism components assemble into supramolecular cellular structures to mediate functional compartmentalization within the cytoplasmic membrane of the bacterial cell. This cellular compartmentalization could play important roles in the processes of RNA degradation and maturation. These components include Hfq, the RNA chaperone protein, which is involved in the post-transcriptional control of protein synthesis mainly by the virtue of its interactions with several small regulatory ncRNAs (sRNA). The Escherichia coli Hfq is structurally organized into two domains. An N-terminal domain that folds as strongly bent β-sheets within individual protomers to…
Inhibition of the Cysteine Protease Human Cathepsin L by Triazine Nitriles: Amide⋅⋅⋅Heteroarene π-Stacking Interactions and Chalcogen Bonding in the …
2016
We report an extensive "heteroarene scan" of triazine nitrile ligands of the cysteine protease human cathepsin L (hCatL) to investigate π-stacking on the peptide amide bond Gly67-Gly68 at the entrance of the S3 pocket. This heteroarene⋅⋅⋅peptide bond stacking was supported by a co-crystal structure of an imidazopyridine ligand with hCatL. Inhibitory constants (Ki ) are strongly influenced by the diverse nature of the heterocycles and specific interactions with the local environment of the S3 pocket. Binding affinities vary by three orders of magnitude. All heteroaromatic ligands feature enhanced binding by comparison with hydrocarbon analogues. Predicted energetic contributions from the ori…
AML-associated Flt3 kinase domain mutations show signal transduction differences compared with Flt3 ITD mutations
2005
Activating mutations of Flt3 are found in approximately one third of patients with acute myeloid leukemia (AML) and are an attractive drug target. Two classes of Flt3 mutations occur: internal tandem duplications (ITDs) in the juxtamembrane and point mutations in the tyrosine kinase domain (TKD). We and others have shown that Flt3-ITD induced aberrant signaling including strong activation of signal transducer and activator of transcription 5 (STAT5) and repression of CCAAT/estradiol-binding protein α (c/EBPα) and Pu.1. Here, we compared the signaling properties of Flt3-ITD versus Flt3-TKD in myeloid progenitor cells. We demonstrate that Flt3-TKD mutations induced autonomous growth of 32D ce…
Relationship between within-host fitness and virulence in the vesicular stomatitis virus: correlation with partial decoupling.
2012
ABSTRACT Given the parasitic nature of viruses, it is sometimes assumed that rates of viral replication and dissemination within hosts (within-host fitness) correlate with virulence. However, there is currently little empirical evidence supporting this principle. To test this, we quantified the fitness and virulence of 21 single- or double-nucleotide mutants of the vesicular stomatitis virus in baby hamster kidney cells (BHK-21). We found that, overall, these two traits correlated positively, but significant outliers were identified. Particularly, a single mutation in the conserved C terminus of the N nucleocapsid (U1323A) had a strongly deleterious fitness effect but did not alter or even …
Molecular modeling approaches in the discovery of new drugs for anti-cancer therapy: the investigation of p53-MDM2 interaction and its inhibition by …
2010
The mdm2 oncogene product, MDM2, is an ubiquitin protein ligase that inhibits the transcriptional activity of the tumor suppressor p53 and promotes its degradation. About 50% of all human cancers present mutations or deletions in the TP53 gene. In the remaining half of all human neoplasias that express the wild-type protein, aberrations of p53 regula- tors, such as MDM2, account for p53 inhibition. For this reason, designing small-molecule inhibitors of the p53-MDM2 protein-protein interaction is a promising strategy for the treatment of cancers retaining wild-type p53. The development of inhibitors has been challenging. Although many small-molecule MDM2 inhibitors have shown potent in vitr…
Development of novel dipeptide-like rhodesain inhibitors containing the 3-bromoisoxazoline warhead in a constrained conformation.
2015
Novel dipeptide-like rhodesain inhibitors containing the 3-bromoisoxazoline warhead in a constrained conformation were developed; some of them possess K(i) values in the micromolar range. We studied the structure-activity relationship of these derivatives and we performed docking studies, which allowed us to find out the key interactions established by the inhibitors with the target enzyme. Biological results indicate that the nature of the P2 and P3 substituents and their binding to the S2/S3 pockets is strictly interdependent.
A novel putative insect chitinase with multiple catalytic domains: hormonal regulation during metamorphosis
2002
0264-6021 (Print) Journal Article Research Support, Non-U.S. Gov't; We have used differential display to identify genes that are regulated by juvenile hormone in the epidermis of the beetle Tenebrio molitor. One of the genes encodes T. molitor chitinase 5 (TmChit5), a chitinase possessing an unusual structure. Sequence analysis of TmChit5 identified five 'chitinase units' of approx. 480 amino acids with similarity to chitinase family 18. These units are separated by less conserved regions containing putative PEST (rich in proline, glutamic acid, serine and threonine) sequences, putative chitin-binding domains and mucin domains. Northern-blot analysis identified a single transcript of approx…
The Fibril-associated Collagen IX Provides a Novel Mechanism for Cell Adhesion to Cartilaginous Matrix
2004
Collagen IX is the prototype fibril-associated collagen with interruptions in triple helix. In human cartilage it covers collagen fibrils, but its putative cellular receptors have been unknown. The reverse transcription-PCR analysis of human fetal tissues suggested that based on their distribution all four collagen receptor integrins, namely alpha1beta1, alpha2beta1, alpha10beta1, and alpha11beta1, are possible receptors for collagen IX. Furthermore primary chondrocytes and chondrosarcoma cells express the four integrins simultaneously. Chondrosarcoma cells, as well as Chinese hamster ovary cells transfected to express alpha1beta1, alpha2beta1, or alpha10beta1 integrin as their only collage…