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Identification et caractérisation des sites de transport de CadA, l'ATPase-cadmium de Listeria Monocytogenes.

Abstract : P1-type ATPases transport heavy metals across the membrane against their
electrochemical gradient using the hydrolysis of ATP as energy source. In 1992, a study
reported that 36% of Listeria monocytogenes were resistant to high Cd2+ concentrations. This
resistance was associated to the presence of plasmids, among which pLm74 presents an
open reading frame coding for a polypeptide of 711 amino acids, named CadA. This
polypeptide possesses 3 consensus sequences of P-type ATPases, the DKTGT, MXTGD
and TGDGXNDXP motifs, as well as 2 consensus sequences of P1-type ATPases, the
CXXC and CPC motifs. In the present work we expressed CadA in the yeast Saccharomyces
cerevisae and used the phenotype of sensitivity to cadmium induced by CadA as a screening
tool for mutants produced by site-directed mutagenesis. We also demonstrated that CadA
can use Cd-ATP instead of Mg-ATP as ATP substrate to accomplish its enzymatic cycle.
Four transmembrane helices (3, 4, 6 and 8) might constitute the Cd2+ transport site of CadA.
Among them M149, C354 and T684 might participate in transport sites whereas E164 and
C356 could be important in the dissociation process of cadmium. P355 and D692 could be
necessary for the phosphorylation. Finally, the study of chimeric ATPases suggests a
regulatory role of the ATP binding domain.
keyword : CadA ATPase
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https://tel.archives-ouvertes.fr/tel-00121780
Contributor : Chen-Chou Wu <>
Submitted on : Friday, December 22, 2006 - 7:24:00 AM
Last modification on : Friday, November 6, 2020 - 4:14:21 AM
Long-term archiving on: : Tuesday, April 6, 2010 - 8:10:20 PM

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  • HAL Id : tel-00121780, version 1

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Citation

Chen-Chou Wu. Identification et caractérisation des sites de transport de CadA, l'ATPase-cadmium de Listeria Monocytogenes.. Biochimie [q-bio.BM]. Université Joseph-Fourier - Grenoble I, 2005. Français. ⟨tel-00121780⟩

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