Immunity proteins to pore-forming colicins: structure-function relationships.

David Espesset (1) , Philippe Piet (1) , Claude Lazdunski (1) , Vincent Géli (1)

1 LISM - Laboratoire d'ingénierie des systèmes macromoléculaires

Colicin A and B immunity proteins (Cai and Cbi, respectively) are homologous integral membrane proteins that interact within the core of the lipid bilayer with hydrophobic transmembrane helices of the corresponding colicin channel. By using various approaches (exchange of hydrophilic loops between Cai and Cbi, construction of Cbi/Cai hybrids, production of Cai as two fragments), we studied the structure-function relationships of Cai and Cbi. The results revealed unexpectedly high structural constraints for the function of these proteins. The periplasmic loops of Cai and Cbi did not carry the determinants for colicin recognition although most of these loops were required for Cai function; the cytoplasmic loop of Cai was found to be involved in topology and function of Cai. The immunity function did not seem to be confined to a particular region of the immunity proteins.

Mots clés: Colicin; Colicin immunity protein; Molecular biology; Integral membrane protein

Domaines: Biologie structurale [q-bio.BM]

David Espesset, Philippe Piet, Claude Lazdunski, Vincent Géli. Immunity proteins to pore-forming colicins: structure-function relationships.. Molecular Microbiology, 1994, 13 (6), pp.1111-1120. ⟨10.1111/j.1365-2958.1994.tb00502.x⟩. ⟨hal-03502904⟩