Publications (15) View all
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Dataset: Bordello09 ChemPhysChem10p931 SupportingInformation
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Dataset: alsoufi05 JACS127p8775 SupportingInfo
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Article: Isolation, characterization and lipid-binding properties of the recalcitrant FtsA division protein from Escherichia coli.
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ABSTRACT: We have obtained milligram amounts of highly pure Escherichia coli division protein FtsA from inclusion bodies with an optimized purification method that, by overcoming the reluctance of FtsA to be purified, surmounts a bottleneck for the analysis of the molecular basis of FtsA function. Purified FtsA is folded, mostly monomeric and interacts with lipids. The apparent affinity of FtsA binding to the inner membrane is ten-fold higher than to phospholipids, suggesting that inner membrane proteins could modulate FtsA-membrane interactions. Binding of FtsA to lipids and membranes is insensitive to ionic strength, indicating that a net contribution of hydrophobic interactions is involved in the association of FtsA to lipid/membrane structures.PLoS ONE 01/2012; 7(6):e39829. · 4.09 Impact Factor -
Article: Host-assisted guest self-assembly: enhancement of the dimerization of pyronines Y and B by gamma-cyclodextrin.
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ABSTRACT: Buckle up! The dimerization of small fluorescent guests is strongly enhanced in presence of a cyclodextrin host. The host cavity acts like a belt to assist the self-assembly of guests (see picture). Small variations in the guest structure have significant influence on the stability and geometry of the aggregates.The role of small variations in the structural properties of host and guest molecules on the stoichiometry and strength of supramolecular associations is analyzed. Earlier we found that a change in substituents from pyronine B to pyronine Y has a dramatic effect on both the stability and the dynamics of the association of these guests with beta-cyclodextrin as host. Now we study the association between these two pyronines and a cyclodextrin with a bigger cavity (gamma-cyclodextrin) using UV/Vis absorption and fluorescence spectroscopy. The absorption spectra of the pyronines show complex variations with cyclodextrin concentration indicating that pyronine dimerization is strongly enhanced inside the cavity of the cyclodextrin. A full model is proposed and the equilibrium constants of the involved processes and the absorption and emission spectra of the different species are estimated. The equilibrium constants of the formation of complexed dimers are much higher than those for free dimerization or for the inclusion of a single guest. The gamma-cyclodextrin host acts like a belt to assist the guest self-assembly. The differences in the stability of pyronine B and pyronine Y dimers are explained on the basis of their structure and geometry.ChemPhysChem 05/2009; 10(6):931-9. · 3.41 Impact Factor -
Article: Dynamic interaction of the Escherichia coli cell division ZipA and FtsZ proteins evidenced in nanodiscs.
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ABSTRACT: The full-length ZipA protein from Escherichia coli, one of the essential components of the division proto-ring that provides membrane tethering to the septation FtsZ protein, has been incorporated in single copy into nanodiscs formed by a membrane scaffold protein encircling an E. coli phospholipid mixture. This is an acellular system that reproduces the assembly of part of the cell division components. ZipA contained in nanodiscs (Nd-ZipA) retains the ability to interact with FtsZ oligomers and with FtsZ polymers. Interactions with FtsZ occur at similar strengths as those involved in the binding of the soluble form of ZipA, lacking the transmembrane region, suggesting that the transmembrane region of ZipA has little influence on the formation of the ZipA·FtsZ complex. Peptides containing partial sequences of the C terminus of FtsZ compete with FtsZ polymers for binding to Nd-ZipA. The affinity of Nd-ZipA for the FtsZ polymer formed with GTP or GMPCPP (a slowly hydrolyzable analog of GTP) is moderate (micromolar range) and of similar magnitude as for FtsZ-GDP oligomers. Polymerization does not stabilize the binding of FtsZ to ZipA. This supports the role of ZipA as a passive anchoring device for the proto-ring with little implication, if any, in the regulation of its assembly. Furthermore, it indicates that the tethering of FtsZ to the membrane shows sufficient plasticity to allow for its release from noncentral regions of the cytoplasmic membrane and its subsequent relocation to midcell when demanded by the assembly of a division ring.Journal of Biological Chemistry 07/2012; 287(36):30097-104. · 4.77 Impact Factor
