1H, 15N and 13C resonance assignment of the N-terminal C39 peptidase-like domain of the ABC transporter Haemolysin B (HlyB)

ATP-binding cassette (ABC) transporters are ubiquitous integral membrane proteins, which catalyze the translocation of molecules across biological membranes in an ATP-dependent manner. Despite the diversity in the transported substrates, they all share the same architecture, comprised of two transmembrane (TMD) and two nucleotide-binding domains (NBD). Members of the bacteriocin ABC transporter subfamily feature a special domain, belonging to the C39 (cystein protease family 39) peptidase protein family. These domains are assumed to cleave a C-terminal signal sequence from the protein or peptide substrate before or during the transport process. Although the C39 peptidase-like domain of the ABC transporter haemolysin B from E. coli shows no proteolytic activity, it is essential for the function of this transporter. In order to elucidate the contribution of the isolated C39 peptidase-like domain in the whole transport process, the backbone and side chain ¹H, ¹⁵N and ¹³C-NMR chemical shifts have been assigned.