Transmembrane Signaling through a Bacterial Heme Transporter

Abstract

Bacteria use diverse signaling pathways to control gene expression in response to external stimuli. In Gram-negative bacteria, the binding of some nutrients is sensed by their specific outer membrane transporter. A cascade of molecular interactions between several proteins, located in three subcellular compartments, is then used to send this signal from outside to inside the bacteria and upregulate the expression of genes related to the acquisition of these nutrients. We study a heme acquisition system (Has) developed by several commensal and pathogenic bacteria to acquire heme as iron source. Using multidisciplinary approach (NMR, Xray, SAXS and Electron Microscopy) we have determined the structure of multiprotein complexes involved in the Has signaling pathway. Furthermore, we have recently shown, for the first time, that a partially folded protein is involved in this process 1,2,3,4,5. Our current data represent the first detailed characterization of this type of bacterial signaling. Ref: 1:Krieg S et al 2009 PNAS; 2:Caillet-Saguy S et al JACS 2009; 4: Cardoso de Amorim et al PlosOne 2013; Malki et al PlosOne 2014.Wojtowicz et al, in preparation.