Search results for " Regulation"
showing 10 items of 3187 documents
The Monod-Wyman-Changeux allosteric model accounts for the quaternary transition dynamics in wild type and a recombinant mutant human hemoglobin
2012
International audience; The acknowledged success of the Monod-Wyman-Changeux (MWC) allosteric model stems from its efficacy in accounting for the functional behavior of many complex proteins starting with hemoglobin (the paradigmatic case) and extending to channels and receptors. The kinetic aspects of the allosteric model, however, have been often neglected, with the exception of hemoglobin and a few other proteins where conformational relaxations can be triggered by a short and intense laser pulse, and monitored by time-resolved optical spectroscopy. Only recently the application of time-resolved wide-angle X-ray scattering (TR-WAXS), a direct structurally sensitive technique, unveiled th…
Small-angle X-ray Scattering-based Three-dimensional Reconstruction of the Immunogen KLH1 Reveals Different Oxygen-dependent Conformations
2003
For decades the respiratory protein keyhole limpet hemocyanin (KLH1) from the marine gastropod Megathura crenulata has been used widely as a potent immunostimulant, useful hapten carrier, and valuable agent in the treatment of bladder carcinoma. Although much information on the immunological properties of KLH1 is available, biochemical and structural data are still incomplete. Small-angle x-ray scattering revealed the existence of two conformations, an oxy state being slightly more compact than the deoxy state. Based on small-angle scattering curves, a newly developed Monte Carlo algorithm delivered a surface representation of proteins. The massive changes of the surfaces of reconstructed d…
Characterization of the pleiotropic LysR-type transcription regulator LeuO of Escherichia coli
2019
AbstractLeuO is a pleiotropic LysR-type transcriptional regulator (LTTR) and co-regulator of the abundant nucleoid-associated repressor protein H-NS in Gammaproteobacteria. As other LTTRs, LeuO is a tetramer that is formed by dimerization of the N-terminal DNA-binding domain (DBD) and C-terminal effector-binding domain (EBD). To characterize the Escherichia coli LeuO protein, we screened for LeuO mutants that activate the cas (CRISPR-associated/Cascade) promoter more effectively than wild-type LeuO. This yielded nine mutants carrying amino acid substitutions in the dimerization interface of the regulatory EBD, as shown by solving the EBD’s crystal structure. Superimposing of the crystal str…
Structure-based analyses of Salmonella RcsB variants unravel new features of the Rcs regulon
2021
18 páginas, 7 figuras, 2 tablas
Characterization of aCandida albicansgene encoding a putative transcriptional factor required for cell wall integrity
2003
After screening a Candida albicans genome database the product of an open reading frame (ORF) (CA2880) with 49% homology to the product of Saccharomyces cerevisiae YPL133c, a putative transcriptional factor, was identified. The disruption of the C. albicans gene leads to a major sensitivity to calcofluor white and Congo red, a minor sensitivity to sodium dodecyl sulfate, a major resistance to zymolyase, and an alteration of the chemical composition of the cell wall. For these reasons we called it CaCWT1 (for C. albicans cell wall transcription factor). CaCwt1p contains a putative Zn(II) Cys(6) DNA binding domain characteristic of some transcriptional factors and a PAS domain. The CaCWT1 gen…
Structural and Functional Basis for Understanding the Biological Significance of P2X7 Receptor
2020
The P2X7 receptor (P2X7R) possesses a unique structure associated to an as yet not fully understood mechanism of action that facilitates cell permeability to large ionic molecules through the receptor itself and/or nearby membrane proteins. High extracellular adenosine triphosphate (ATP) levels—inexistent in physiological conditions—are required for the receptor to be triggered and contribute to its role in cell damage signaling. The inconsistent data on its activation pathways and the few studies performed in natively expressed human P2X7R have led us to review the structure, activation pathways, and specific cellular location of P2X7R in order to analyze its biological relevance. The ATP-…
The 5' Untranslated Region of the
2018
Many of the virulence traits that make Candida albicans an important human fungal pathogen are regulated on a transcriptional level. Here, we report an important regulatory contribution of translation, which is exerted by the extensive 5′ untranslated regulatory sequence (5′ UTR) of the transcript for the protein Efg1, which determines growth, metabolism, and filamentation in the fungus. The presence of the 5′ UTR is required for efficient translation of Efg1, to promote filamentation. Because transcripts for many relevant regulators contain extensive 5′ UTR sequences, it appears that the virulence of C. albicans depends on the combination of transcriptional and translational regulatory mec…
In murine 3T3 fibroblasts, different second messenger pathways resulting in the induction of NO synthase II (iNOS) converge in the activation of tran…
1996
Transcription factor NF-kappaB is essential for the induction of nitric oxide synthase (NOS) II (iNOS) by bacterial lipopolysaccharide in murine macrophages (Xie, Q. W., Kashiwabara, Y., and Nathan, C. (1994) J. Biol. Chem. 269, 4705-4708). In 3T3 fibroblasts, agents other than cytokines are efficacious inducers of NOS II expression. In addition to cytokines such as interferon-gamma or tumor necrosis factor-alpha, protein kinase C-stimulating agents such as tetradecanoylphorbol-13-acetate, or cyclic AMP-elevating agents such as forskolin and 8-bromo-cAMP markedly increased NOS II mRNA (measured by Sl nuclease and RNase protection analyses), NOS II protein (determined by Western blotting), a…
Two α subunits and one β subunit of meprin zinc-endopeptidases are differentially expressed in the zebrafish Danio rerio
2007
Abstract Meprins are members of the astacin family of metalloproteases expressed in epithelial tissues, intestinal leukocytes and certain cancer cells. In mammals, there are two homologous subunits, which form complex glycosylated disulfide-bonded homo- and heterooligomers. Both human meprin α and meprin β cleave several basement membrane components, suggesting a role in epithelial differentiation and cell migration. There is also evidence that meprin β is involved in immune defence owing to its capability of activating interleukin-1β and the diminished mobility of intestinal leukocytes in meprin β-knockout mice. Here we show for the first time by reverse transcription PCR, immunoblotting a…
Cloning and characterization of PRB1, a Candida albicans gene encoding a putative novel endoprotease B and factors affecting its expression
2002
Abstract Several cDNA fragments corresponding to transcripts differentially expressed under conditions that favor mycelial growth of Candida albicans were identified by the “differential display” technique. One of these was cloned and used as a probe to rescue the full gene from a genomic library of the fungus. The sequence identified a single, uninterrupted open reading frame of 1395 nucleotides encoding a putative protein of 465 residues and a theoretical molecular weight of 50.3 kDa, present in the genome as a single copy located at chromosome 2 in different strains. The gene product showed high homology with subtilisin-like proteases, mainly PRB1, the vacuolar B protease from Saccharomy…