NMR assignment and backbone dynamics of the pore-forming domain of colicin A.

Colicin A protein kills cells by opening voltage-dependent ion channels in the cytoplasmic membrane. The C-terminal domain of colicin A retains the full protein's ability to form membrane pores, making it an excellent model for in vitro studies of protein-membrane interaction. We report here the NMR assignment and backbone dynamics of this domain in solution. The chemical shifts identify ten alpha-helices that match those observed in the crystal structure, while the (15)N{(1)H} NOEs show differential fast mobility for some of the inter-helical loops and the chain ends. This analysis provides the basis for further NMR studies of this channel forming protein and its interactions.