Accueil > Publications > Recherche par années > Années 1990 > 1995

Lazzaroni, JC ; Vianney, A ; Popot, JL ; Benedetti, H ; Samatey, F ; Lazdunski, C ; Portalier, R ; Geli, V

Transmembrane alpha-helix interactions are required for the functional assembly of the escherichia-coli tol complex

Journal of Molecular Biology 246 (1) 1-7

par Administrateur - publié le

Abstract :

TolQ, TolR and TolA are membrane proteins involved in maintaining the structure of Escherichia coli cell envelope. TolQ and TolR span the inner membrane with three and with one a-helical segments, respectively. The tolQ925 mutation (A177V),located in the third putative transmembrane helix of TolQ (TolQ-III), induces cell sensitivity to bile salts and tolerance towards colicin A but not colicin El, unlike a null tolQ mutation, which induces tolerance to all group A colicins. Since TolQ is required for colicin A and Fl uptake, in contrast to TolR, which is necessary only for colicin A, we hypothesized that the tolQ925 mutation might affect an interaction between TolQ and TolR. We therefore searched for suppressor mutations in TolR that would restore cell envelope integrity and colicin A sensitivity to the tolQ925 mutant. Five different tolR alleles were isolated and characterized.