Papers by Andre Vermeglio
The two-electron gate in photosynthetic bacteria
Springer eBooks, Jul 14, 2006
Mode of Action of the ATP-ase Inhibitor Tri-N-butyl-tin in Rhodopseudomonas Sphaeroides Cells
Specific inhibitors of the H+ translocating ATP- ase are important tool in the study of bioenerge... more Specific inhibitors of the H+ translocating ATP- ase are important tool in the study of bioenergetic processes of intact photosynthetic bacteria. Dicyclohexyl carbodiimide (DCCD) (P.C. Maloney, 1979) has been used with some success. More recently, venturicidin (N.P.J. Cotton et al., 1981) has been shown to behave as an energy transfer inhibitor in intact cells of Rhodopseudomonas Capsulata. Although organotin compounds (trialkyltin and triaryltin halides) inhibit the ATP-ase of mitochondria (M.S.Rose, W.N. Aldridge, 1972, K. Cain et al., 1977) and of chlorop lasts (J.M. Gould, 1976, 1978) no report has been published concerning their action in intact photosynthetic bacteria. This is the object of the present work.
Supramolecular Organization of the Photosynthetic Chain in Rhodobacter Sphaeroides
Springer eBooks, 1995

Electron Transfer between Primary and Secondary Donors in Photosynthetic Bacteria: Evidence for “Supercomplexes”
Light-induced oxidation of the primary electron donor P and of the secondary donor cytochrome c2 ... more Light-induced oxidation of the primary electron donor P and of the secondary donor cytochrome c2 was studied in whole cells of Rhodospirillum rubrum in the presence of myxothiazole to slow down their reduction. 1. The primary and secondary electron donors are close to thermodynamic equilibrium during continuous illumination when the rate of the electron transfer is light-limited. This implies a long-range thermodynamic equilibration involving the diffusible cytochrome c2. A different behavior is observed with Rhodobacter sphaeroides R26 whole cells, in which the cytochrome c2 remains trapped within a supercomplex including reaction centers and the cytochrome b/c complex [Joliot, P., et al. (1989) Biochim. Biophys. Acta 975, 336-345]. 2. Under weak flash excitation, the reduction kinetics of the photooxidized primary donor are nearly exponential with a half-time in the hundred microseconds time range. 3. Under strong flash excitation, the reduction of the photooxidized primary donor follows a second-order kinetics. About half of the photooxidized primary donor is reduced in a few milliseconds while the remainder stays oxidized for hundreds of milliseconds despite an excess of secondary donors in their reduced form. The flash intensity dependence of the amplitude of the slow phase of P+ reduction is proportional to the square of the fraction of reaction centers that have undergone a charge separation.(ABSTRACT TRUNCATED AT 250 WORDS)
Interaction between photosynthesis and respiration in facultative phototrophs
Springer eBooks, 2004
Organization of the Electron Transfer Chain in Purple Bacteria at Subzero Temperatures
Springer eBooks, 1995

Reduction of Tellurite and Selenite by Photosynthetic Bacteria
Oxyanions of tellurium and selenium in the form of potassium or sodium salts are toxic for most m... more Oxyanions of tellurium and selenium in the form of potassium or sodium salts are toxic for most microorganisms and animals (1, 2). However high level of resistance has been reported for purple (3) and aerobic anoxygenic photosynthetic bacteria (4) of the alpha subclass of Proteobacteria, and for extreme thermophiles of the genus Thermus (5). This constitutive high level of resistance confers to some of these bacteria the ability to grow at concentrations higher than 2 mg/ml of tellurite (4). This is two to three orders of magnitude higher than the minimal inhibition concentration (MIC) usually determined for most gram-negative bacteria. The toxicity of tellurite and selenite for microorganisms is probably linked to the strong oxidant property of these compounds. Although the mechanisms of resistance to tellurite and selenite have not been characterized in details, several hypotheses have been made (see ref. 5 for a detailed discussion). This includes the repair of cellular damage, reduced uptake and increased efflux or sequestration of the oxyanions. Recently it has been shown that two loci are involved in tellurite resistance in the case of Rhodobacter sphaeroides (6) but the exact role of their products is still unclear. One possible mechanism of protection is the reduction by the bacteria of the oxyanions to the lesser oxidant metallic form. Indeed, formation of black or red colonies due to the intracellular deposition of metallic tellurium or selenium respectively has been observed (7, 8) for bacteria grown in the presence of their corresponding oxyanions. The reduction of the soluble forms (TeO 3 2− , SeO 3 2− ) to the solid metallic forms (Te0, Se0) leads to the intracellular accumulation of metal by the bacteria (see Figure 1 as example). In addition to these reduction processes, Rhodobacter sphaeroides exhibits high resistance to a large number of toxic heavy metals (3). These properties open potential applications in detoxification and bioremediation of polluted waters and soils by photosynthetic bacteria. The aim of our work is to describe the molecular mechanisms involved in these reduction processes. Identification of the genes encoding the different enzymes involved may allow the construction of recombinant plants with new bioremediation capabilities.
Physiological Role Analyzed by Gene Disruption of Membrane-Bound Cytochrome <I>c</I> Working as an Electron Donor to the Photochemical Reaction Center Complex in the Purple Bacterium, <I>Rhodovulum sulfidophilum</I>
Changes in midpoint potentials of hemes by SD-mutagenesis in tetraheme cytochrome subunit of photosynthetic reaction center complex in purple bacteria

Science Access, 2001
Histidine isotopically labeled with C have been incorporated in the RC of Rb. sphaeroides and the... more Histidine isotopically labeled with C have been incorporated in the RC of Rb. sphaeroides and the light-induced FTIR difference spectra for the oxidation of the primary donor P and the reduction of the quinone QA have been measured. The isotope effect on the pure QA /QA spectra provides IR signatures of the His modes that are very comparable to those previously reported for QA reduction in photosystem II. Comparison with published model compounds spectra indicates that the imidazole ring with the RC crystallographic model. In the PQA /PQA FTIR spectra, the contribution of QA reduction on the His vibrations is dominated by that of P oxidation. The large isotope signals from the P/P species observed in the 1140-1090 cm range are assigned for a major part to the perturbation upon P photooxidation of the ring mode of the His serving as axial ligands to the Mg atom of the bacteriochlorophylls in the primary donor.
Method for Producing Carotenoids and Bacteria Used Therefor
ChemInform Abstract: SCHONENDE OX. IN DER GASPHASE 15. MITT. CHLORIERUNG UND OXYCHLORIERUNG VON CYCLOHEXEN
Chemischer Informationsdienst. Organische Chemie, 1971
Die Chlorierung von Cyclohexen (II) bei 450°C verläuft spezifisch zum Hauptprodukt (I) (85% Ausbe... more Die Chlorierung von Cyclohexen (II) bei 450°C verläuft spezifisch zum Hauptprodukt (I) (85% Ausbeute).
Tellurite resistance and reduction by ogligately aerobic photosynthesis bacteria
Applied and Environmental Microbiology, 1996

Chapter 18. Anoxygenic Bacteria
Primary Processes of Photosynthesis, Part 2, 2007
Anoxygenic photosynthetic bacteria transform light energy into chemical free energy according to ... more Anoxygenic photosynthetic bacteria transform light energy into chemical free energy according to a light-induced cyclic electron transfer. This fast cyclic electron transfer is coupled to the translocation of protons and to the formation of an electrochemical potential across the inner membrane, ultimately used for ATP synthesis. This chapter presents a comprehensive overview of our present knowledge of this process with special emphasis on non-sulfur photosynthetic bacteria. Thanks to a multidisciplinary approach combining biophysics, biochemistry and molecular biology, a nearly complete picture of the thermodynamics and kinetic properties, structures and interactions of the different protein complexes involved in this process is now available. Three multimeric transmembrane protein complexes compose the photosynthetic apparatus: the light-harvesting complexes, the photochemical reaction center and the cytochrome bc1 complex. These two last complexes are connected via electron carrier proteins in the periplasmic space and quinone molecules in the membrane. One important peculiarity of species of photosynthetic bacteria is the diversity of the biochemical nature of the immediate electron donor to the reaction center and of the shuttling electron carrier with the cytochrome bc1 complex. The secondary electron donor to the reaction center could be either a tetra-, tri-, or mono-heme cytochrome c tightly bound to the reaction center or a soluble periplasmic monoheme cytochrome c. Different soluble electron carriers (cyt c2, cyt c8, HiPIP) connect the reaction center and the cytochrome bc1 complex, depending upon the considered species. The rates of electron transfer between these different partners have been determined by flash spectroscopy. Site-directed mutagenesis experiments, based on the 3D structure of the various components of the photosynthetic apparatus, have underlined the importance of both nonpolar and electrostatic interactions in the docking process of these different partners. In some cases, a higher level of interaction between the complexes of the photosynthetic apparatus has been determined by electron and atomic force microscopy techniques, highlighting their supramolecular organization in native membranes.
More than Two Structurally Distinct Types of Antenna in Rhodospirillales
Advances in Photosynthesis Research, 1984
Resonance Raman (RR) spectroscopy can be used to yield information about ground state interaction... more Resonance Raman (RR) spectroscopy can be used to yield information about ground state interactions assumed by bacteriochlorophyll a (BChl) in antenna structures of Rhodospirillales. This technique permits investigations of the local environment of BChl molecules within the intracytoplasmic membrane and within antenna complexes, and, in particular, of their bonding with their host polypeptides (Lutz, 1981). Using this method, we studied chromatophores and antenna complexes of several species of Rhodospirillaceae and Chromatiaceae in order to compare, on a structural basis, complexes defined by their biochemical and electronic properties.
Reduction of Oxyanions by Photosynthetic Bacteria and Escherichia Coli: Role of the Nitrate Reductase in the Reduction of Tellurite and Selenate
Photosynthesis: from Light to Biosphere, 1995

Science, 2007
Leguminous plants (such as peas and soybeans) and rhizobial soil bacteria are symbiotic partners ... more Leguminous plants (such as peas and soybeans) and rhizobial soil bacteria are symbiotic partners that communicate through molecular signaling pathways, resulting in the formation of nodules on legume roots and occasionally stems that house nitrogen-fixing bacteria. Nodule formation has been assumed to be exclusively initiated by the binding of bacterial, host-specific lipochito-oligosaccharidic Nod factors, encoded by the nodABC genes, to kinase-like receptors of the plant. Here we show by complete genome sequencing of two symbiotic, photosynthetic, Bradyrhizobium strains, BTAi1 and ORS278, that canonical nodABC genes and typical lipochito-oligosaccharidic Nod factors are not required for symbiosis in some legumes. Mutational analyses indicated that these unique rhizobia use an alternative pathway to initiate symbioses, where a purine derivative may play a key role in triggering nodule formation.
Photosynthesis: Photobiochemistry and Photobiophysics
Plant Science, 2001
FEBS Letters, 1991
The photooxidation of c 559, c 556, and c 552 hemes in Rhodopseudomonas viridis cytochrome has be... more The photooxidation of c 559, c 556, and c 552 hemes in Rhodopseudomonas viridis cytochrome has been characterized by light‐induced FTIR difference spectroscopy. Apart from the common features at 1659 cm−1 and 1561/1551 cm−1 which could arise from one (or possibly two) peptide bond(s), no evidence for major structural rearrangement of the polypeptide backbone was observed. A significant difference with respect to redox‐induced FTIR spectra of cytochrome c is the absence of the Tyr marker at 1514/1518 cm−1 in Rps. viridis cytochrome, indicating that the localized shift of a Tyr side chain observed between ferro‐ and ferri‐cytochrome c does not occur in Rps. viridis cytochrome.
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Papers by Andre Vermeglio