title: ActA is a dimer.
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.
authors.affiliation: Unité des Interactions Bactéries-Cellules, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris Cedex 15, France.
authors.forename: P
authors.initials: P
authors.lastname: Mourrain
authors.forename: I
authors.initials: I
authors.lastname: Lasa
authors.forename: A
authors.initials: A
authors.lastname: Gautreau
authors.forename: E
authors.initials: E
authors.lastname: Gouin
authors.forename: A
authors.initials: A
authors.lastname: Pugsley
authors.forename: P
authors.initials: P
authors.lastname: Cossart
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D019281:Dimerization; D008089:Listeria monocytogenes / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; C072980:actA protein, Listeria monocytogenes