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ActA is a dimer
- Philippe Mourrain*,
- Iñigo Lasa*,
- Alexis Gautreau*,
- Edith Gouin*,
- Anthony Pugsley†, and
- Pascale Cossart*,‡
- *Unité des Interactions Bactéries-Cellules, and †Unité de Génétique Moléculaire (Centre National de la Recherche Scientifique Unité de Recherche Associée 1149), Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris Cedex 15, France
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Edited by Thomas D. Pollard, Salk Institute for Biological Studies, La Jolla, CA, and approved July 10, 1997 (received for review January 15, 1997)
Abstract
ActA, a surface protein of Listeria monocytogenes, is able to induce continuous actin polymerization at the rear of the bacterium, in the cytosol of the infected cells. Its N-terminal domain is sufficient to induce actin tail formation and movement. Here, we demonstrate, using the yeast two-hybrid system, that the N-terminal domain of ActA may form homodimers. By using chemical cross-linking to explore the possibility that ActA could be a multimer on the surface of the bacteria, we show that ActA is a dimer. Cross-linking experiments on various L. monocytogenes strains expressing different ActA variants demonstrated that the region spanning amino acids 97–126, and previously identified as critical for actin tail formation, is also critical for dimer formation. A model of actin polymerization by L. monocytogenes, involving the ActA dimer, is presented.
Footnotes
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↵ ‡ To whom reprint requests should be addressed. e-mail: pcossart{at}pasteur.fr.
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This paper was submitted directly (Track II) to the Proceedings Office.
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Abbreviations: VASP, vasodilator-stimulated phosphoprotein; DBD, DNA binding domain; BS3, bis(sulfosuccinimidyl) suberate; DSP, dithio-bis(succinimidylpropionate); AD, activation domain; β-gal, β-galactosidase.
- Copyright © 1997, The National Academy of Sciences of the USA
