Publications

2009

• Erratum to : Application of time-resolved circular dichroism to the study of conformational changes in photochemical and photobiological processes
  
  • Hache François
  Journal of Photochemistry and Photobiology A: Chemistry, Elsevier, 2009, 205 (1), pp.77. (10.1016/j.jphotochem.2009.05.017)
  DOI : 10.1016/j.jphotochem.2009.05.017
• Interaction of carbon monoxide with the apoptosis-inducing cytochrome c-cardiolipin complex
  
  • Kapetanaki Sofia M.
  • Silkstone G.
  • Husu I.
  • Liebl Ursula
  • Wilson M.T.
  • Vos Marten H.
  Biochemistry, American Chemical Society, 2009, 48 (7), pp.1613. The interaction of mitochondrial cytochrome (cyt) c with cardiolipin (CL) is involved in the initial stages of apoptosis. This interaction can lead to destabilization of the heme−Met80 bond and peroxidase activity [Basova, L. V., et al. (2007) Biochemistry 46, 3423−3434]. We show that under these conditions carbon monoxide (CO) binds to cyt c, with very high affinity (5 × 107 M−1), in contrast to the native cyt c protein involved in respiratory electron shuttling that does not bind CO. Binding of CO to the cyt c−CL complex inhibits its peroxidase activity. Photodissociated CO from the cyt c−CL complex shows <20% picosecond geminate rebinding and predominantly bimolecular rebinding, with a second-order rate constant of 107 M−1 s−1, an order of magnitude higher than in myoglobin. These findings contrast with those of Met80X mutant cyt c, where picosecond geminate recombination dominates due to the rigidity of the protein. Our data imply that CL leads to substantial changes in protein conformation and flexibility, allowing access of ligands to the heme. Together with the findings that (a) 30 CL per cyt c are required for full CO binding and (b) salt-induced dissociation indicates that the two negative headgroup charges interact with 5 positive surface charges of the protein, these results are consistent with a CL anchorage model with an acyl chain impaled in the protein [Kalanxhi, E., and Wallace, C. J. A. (2007) Biochem. J. 407, 179−187]. The affinity of CO for the complex is high enough to envisage an antiapoptotic effect of nanomolar CO concentrations via inhibition of the cyt c peroxidase activity. (10.1021/bi801817v)
  DOI : 10.1021/bi801817v
• Picosecond Transient Circular Dichroism of the Photoreceptor Protein of the Light-Adapted Form of Blepharisma Japonicum
  
  • Hache François
  • Khuc Mai-Thu
  • Brazard Johanna
  • Plaza Pascal
  • Martin Monique M.
  • Checcucci Giovanni
  • Lenci Francesco
  Chemical Physics Letters, Elsevier, 2009, 483, pp.133. We present a picosecond transient circular dichroism study of OBIP, the putative photoreceptor protein involved in the photophobic response of Blepharisma Japonicum. The probe wavelength was chosen at 230 nm. The results are compared to those of the isolated chromophore, OxyBP, in solution. The CD changes in OBIP and OxyBP do not show the same dynamics: OBIP's signal relaxes in a few ps whereas no such decay is obtained for OxyBP. This observation brings support to the formerly evoked existence of a fast photoinduced reaction in the chromoprotein, and demonstrates the implication of local geometrical changes that accompany this process. (10.1016/j.cplett.2009.10.059)
  DOI : 10.1016/j.cplett.2009.10.059
• Apports récents des techniques de quantification de la fibrose pour l'examen anatomopathologique en transplantation rénale
  
  • Servais A.
  • Meas-Yedid V.
  • Morelon E.
  • Strupler Mathias
  • Schanne-Klein Marie-Claire
  • Legendre C.
  • Olivo-Marin J.-C.
  • Thervet É.
  Médecine/Sciences, EDP Sciences, 2009, 25 (11), pp.945-950. La néphropathie chronique d'allogreffe constitue la cause principale de perte des greffons rénaux à long terme. Elle peut être détectée précocement par des biopsies de dépistage effectuées de manière systématique. La classification usuelle, semi-quantitative, souffre d'une mauvaise reproductibilité. Diverses méthodes morphométriques ont donc été développées pour quantifier la fibrose interstitielle qui caractérise cette néphropathie. Certaines utilisent la coloration spécifique par le rouge Sirius. L'analyse d'image couleur par segmentation permet une quantification automatique, rapide et robuste de la fibrose interstitielle. Elle utilise une segmentation couleur associée à une analyse de couleur, de localisation spatiale et de forme sur des biopsies colorées au trichrome de Masson. À l'avenir, l'étude des collagènes fibrillaires par la génération de second harmonique pourrait permettre une approche spécifique des composants de la fibrose. (10.1051/medsci/20092511945)
  DOI : 10.1051/medsci/20092511945
• Unobtrusive interferometer tracking by path length oscillation for multidimensional spectroscopy
  
  • Lee Kevin F.
  • Bonvalet Adeline
  • Nuernberger Patrick
  • Joffre Manuel
  Optics Express, Optical Society of America - OSA Publishing, 2009, 17 (15), pp.12379-12384. We track the path difference between interferometer arms with few-nanometer accuracy without adding optics to the beam path. We measure the interference of a helium-neon beam that copropagates through the interferometer with midinfrared pulses used for multidimensional spectroscopy. This can indicate motion, but not direction. By oscillating the path length of one arm with a mirror on a piezoelectric stack and monitoring the oscillations of the recombined helium-neon beam, the direction can be calculated, and the path delay can be continuously tracked. © 2009 Optical Society of America. (10.1364/OE.17.012379)
  DOI : 10.1364/OE.17.012379
• Suppression of perturbed free-induction decay and noise in experimental ultrafast pump-probe data
  
  • Nuernberger Patrick
  • Lee Kevin F.
  • Bonvalet Adeline
  • Polack Thomas
  • Vos Marten H.
  • Alexandrou Antigoni
  • Joffre Manuel
  Optics Letters, Optical Society of America - OSA Publishing, 2009, 34 (20), pp.3226-3228. We apply a Fourier filtering technique for the global removal of coherent contributions, like perturbed freeinduction decay, and noise, to experimental pump-probe spectra. A further filtering scheme gains access to spectra otherwise only recordable by scanning the probe's center frequency with adjustable spectral resolution. These methods cleanse pump-probe data and allow improved visualization and simpler analysis of the contained dynamics. We demonstrate these filters using visible pump/mid-infrared probe spectroscopy of ligand dissociation in carboxyhemoglobin. Cop. 2009 Optical Society of America. (10.1364/OL.34.003226)
  DOI : 10.1364/OL.34.003226
• Heme ligand binding properties and intradimer interactions in the full-length sensor protein Dos from Escherichia coli and its isolated heme domain
  
  • Lechauve C.
  • Bouzhir-Sima Latifa
  • Yamashita Taku
  • Marden M.C.
  • Vos Marten H.
  • Liebl Ursula
  • Kiger L.
  Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 2009, 284 (52), pp.36146. Dos from Escherichia coli is a bacterial gas sensor protein comprising a heme-containing gas sensor domain and a phosphodiesterase catalytic domain. Using a combination of static light scattering and gel filtration experiments, we established that, as are many other sensor proteins, the full-length protein is dimeric. The full-length dimer (association constant <10 nm) is more stable than the dimeric heme domain (association constant ∼1 μm), and the dimer interface presumably includes both sensor and catalytic domains. Ultrafast spectroscopic studies showed little influence of the catalytic domain on kinetic processes in the direct vicinity of the heme. By contrast, the properties of ligand (CO and O2) binding to the heme in the sensor domain, occurring on a microsecond to second time scale, were found to be influenced by (i) the presence of the catalytic domain, (ii) the dimerization state, and in dimers, (iii) the ligation state of the other subunit. These results imply allosteric interactions within dimers. Steady-state titrations demonstrated marked cooperativity in oxygen binding to both the full-length protein and the isolated heme domain, a feature not reported to date for any dimeric sensor protein. Analysis of a variety of time-resolved experiments showed that Met-95 plays a major role in the intradimer interactions. The intrinsic binding and dissociation rates of Met-95 to the heme were modulated ∼10-fold by intradimer and sensor-catalytic domain interactions. Dimerization effects were also observed for cyanide binding to the ferric heme domains, suggesting a similar role for Met-95 in ferric proteins. (10.1074/jbc.M109.066811)
  DOI : 10.1074/jbc.M109.066811
• Extended fano model of extraordinary electromagnetic transmission through subwavelength hole arrays in the terahertz domain
  
  • Masson Jean-Baptiste
  • Podzorov Alexander
  • Gallot Guilhem
  Optics Express, Optical Society of America - OSA Publishing, 2009, 17 (17), pp.15280-15291. We developed an extended Fano model describing the Extraordinary Electromagnetic Transmission (EET) through arrays of subwavelength apertures, based on terahertz transmission measurements of arrays of various hole size and shapes. Considering a frequency-dependent coupling between resonant and non-resonant pathways, this model gives access to a simple analytical description of EET, provides good agreement with experimental data, and offers new parameters describing the influence of the hole size and shape on the transmitted signal. Cop. 2009 Optical Society of America. (10.1364/OE.17.015280)
  DOI : 10.1364/OE.17.015280
• Removing cross-phase modulation from midinfrared chirped-pulse upconversion spectra
  
  • Lee Kevin F.
  • Nuernberger Patrick
  • Bonvalet Adeline
  • Joffre Manuel
  Optics Express, Optical Society of America - OSA Publishing, 2009, 17 (21), pp.18738-18744. We observe that narrow spectral features in mid-infrared spectra obtained by chirped-pulse up-conversion are strongly distorted by crossphase modulation between the mid-infrared field and the chirped pulse. We discuss the consequences of this effect on spectral resolution, and introduce a correction method that recovers masked lines. This simple correction can be applied either when the upconverted field is fully characterized, such as in multidimensional spectroscopy, or when causality can be used, such as in absorption spectroscopy, which we demonstrate experimentally. Cop.2009 Optical Society of America. (10.1364/OE.17.018738)
  DOI : 10.1364/OE.17.018738
• Femto-second ultrashort laser wakefield electron bunch-duration measurements: a prism-based dispersion visible-to-IR spectrometer
  
  • Lim J.
  • Faure Jérôme
  • Gallot Guilhem
  • Lundh O.
  • Rechatin C.
  • Malka Victor
  , 2009, pp.735919. (10.1117/12.829134)
  DOI : 10.1117/12.829134
• HIV-1 IN alternative molecular recognition of DNA induced by raltegravir resistance mutations
  
  • Mouscadet J.-F.
  • Arora Rakesh
  • André J.
  • Lambry Jean-Christophe
  • Delelis O.
  • Malet I.
  • Marcelin A.-G.
  • Calvez V.
  • Tchertanov L.
  Journal of Molecular Recognition, Wiley, 2009, 22 (6), pp.480-494. Virologic failure during treatment with raltegravir, the first effective drug targeting HIV integrase, is associated with two exclusive pathways involving either Q148H/R/K, G140S/A or N155H mutations. We carried out a detailed analysis of the molecular and structural effects of these mutations. We observed no topological change in the integrase core domain, with conservation of a newly identified V-shaped hairpin containing the Q148 residue, in particular. In contrast, the mutations greatly altered the specificity of DNA recognition by integrase. The native residues displayed a clear preference for adenine, whereas the mutant residues strongly favored pyrimidines. Raltegravir may bind to N155 and/or Q148 residues as an adenine bioisoster. This may account for the selected mutations impairing raltegravir binding while allowing alternative DNA recognition by integrase. This study opens up new opportunities for the design of integrase inhibitors active against raltegravir-resistant viruses. Copyright Cop. 2009 John Wiley and Sons, Ltd. Supporting information may be found in the online version of this article. (10.1002/jmr.970)
  DOI : 10.1002/jmr.970