Interaction of a partially disordered antisigma factor with its partner, the signaling domain of the TonB-dependent transporter HasR.

Idir Malki (1, 2) , Catherine Simenel (2) , Halina Wojtowicz (2) , Gisele Cardoso de Amorim (2) , Ada Prochnicka-Chalufour (2) , Sylviane Hoos (3) , Bertrand Raynal (3) , Patrick England (3) , Alain Chaffotte (2) , Muriel Delepierre (2) , Philippe Delepelaire (4) , Nadia Izadi-Pruneyre (2)

1 Cellule Pasteur UPMC
2 Résonance Magnétique Nucléaire des Biomolécules
3 Biophysique des macromolécules et leurs interactions
4 LBPC-PM (UMR_7099) - Laboratoire de biologie physico-chimique des protéines membranaires

Bacteria use diverse signaling pathways to control gene expression in response to external stimuli. In Gram-negative bacteria, the binding of a nutrient is sensed by an outer membrane transporter. This signal is then transmitted to an antisigma factor and subsequently to the cytoplasm where an ECF sigma factor induces expression of genes related to the acquisition of this nutrient. The molecular interactions involved in this transmembrane signaling are poorly understood and structural data on this family of antisigma factor are rare. Here, we present the first structural study of the periplasmic domain of an antisigma factor and its interaction with the transporter. The study concerns the signaling in the heme acquisition system (Has) of Serratia marcescens. Our data support unprecedented partially disordered periplasmic domain of an anti-sigma factor HasS in contact with a membrane-mimicking environment. We solved the 3D structure of the signaling domain of HasR transporter and identified the residues at the HasS-HasR interface. Their conservation in several bacteria suggests wider significance of the proposed model for the understanding of bacterial transmembrane signaling.

Domains: Biophysics; Structural Biology [q-bio.BM]

Idir Malki, Catherine Simenel, Halina Wojtowicz, Gisele Cardoso de Amorim, Ada Prochnicka-Chalufour, et al.. Interaction of a partially disordered antisigma factor with its partner, the signaling domain of the TonB-dependent transporter HasR.. PLoS ONE, 2013, 9 (4), pp.e89502. ⟨10.1371/journal.pone.0089502⟩. ⟨pasteur-01130431⟩