Are you Sophie Hanique?

Claim your profile

Publications (3)13.51 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Two-color sum-frequency generation spectroscopy (2C-SFG) is used to probe the molecular and electronic properties of an adsorbed layer of the green fluorescent protein mutant 2 (GFPmut2) on a platinum (111) substrate. First, the spectroscopic measurements, performed under different polarization combinations, and atomic force microscopy (AFM) show that the GFPmut2 proteins form a fairly ordered monolayer on the platinum surface. Next, the nonlinear spectroscopic data provide evidence of particular coupling phenomena between the GFPmut2 vibrational and electronic properties. This is revealed by the occurrence of two doubly resonant sum-frequency generation processes for molecules having both their Raman and infrared transition moments in a direction perpendicular to the sample plane. Finally, our 2C-SFG analysis reveals two electronic transitions corresponding to the absorption and fluorescence energy levels which are related to two different GFPmut2 conformations: the B (anionic) and I forms, respectively. Their observation and wavelength positions attest the keeping of the GFPmut2 electronic properties upon adsorption on the metallic surface.
    No preview · Article · Sep 2004 · Langmuir
  • [Show abstract] [Hide abstract]
    ABSTRACT: The BlaR1 protein is a penicillin-sensory transducer involved in the induction of the Bacillus licheniformis beta-lactamase. The amino-terminal domain of the protein exhibits four transmembrane segments (TM1-TM4) that form a four-alpha-helix bundle embedded in the plasma bilayer. The carboxyl-terminal domain of 250 amino acids (BlaR-CTD) fused at the carboxyl end of TM4 possesses the amino acid sequence signature of penicillin-binding proteins. This membrane topology suggests that BlaR-CTD and the BlaR-amino-terminal domain are responsible for signal reception and signal transduction, respectively. With the use of phage display experiments, we highlight herein an interaction between BlaR-CTD and the extracellular, 63-amino acid L2 loop connecting TM2 and TM3. This interaction does not occur in the presence of penicillin. This result suggests that binding of the antibiotic to BlaR1 might entail the release of the interaction between L2 and BlaR-CTD, causing a motion of the alpha-helix bundle and transfer of the information to the cytoplasm of the cell. In addition, fluorescence spectroscopy, CD, and Fourier transform IR spectroscopy experiments indicate that in contrast to the behavior of the corresponding Staphylococcus aureus protein, the beta-lactam antibiotic does not induce a drastic conformational change in B. licheniformis BlaR-CTD.
    No preview · Article · May 2004 · Journal of Biological Chemistry
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The ybxI gene of Bacillus subtilis 168 encodes a preprotein of 267 amino acid residues, including a putative signal peptide of 23 residues. The YbxI primary structure exhibits high similarity scores with two members of the superfamily of the serine penicillin-recognizing enzymes: the class D β-lactamases and the hydrophilic carboxy-terminal domains of the BlaR and MecR penicillin receptors. To determine the function and the activity of this putative penicillin-recognizing enzyme, we have subcloned the ybxI gene in the pET-26b expression vector. Transformation of Escherichia coli BL21(DE3) by the recombinant plasmid pCIP51 resulted in the export of the mature YbxI in the periplasm as a water-soluble protein. The recombinant protein was purified to 95% homogeneity. YbxI interacts with several β-lactam antibiotics and can hydrolyze some of them. YbxI is not inactivated by clavulanic acid. The YbxI function and its enzymatic activity in B. subtilis remain unknown. The acyl-enzyme obtained after incubation of YbxI with a fluorescent derivative of ampicillin can be detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, confirming that YbxI can be acylated by β-lactam antibiotics. YbxI does not hydrolyze some of the standard substrates of d-alanyl-d-alanine peptidases, the targets of penicillin. YbxI belongs to the penicillin-recognizing enzyme family but has an activity intermediate between those of a penicillin-binding protein and a β-lactamase.
    Preview · Article · Mar 2004 · Antimicrobial Agents and Chemotherapy