(1)H, (13)C and (15)N assignments of CdnL, an essential protein in Myxococcus xanthus

CdnL, an essential protein in Myxococcus xanthus and several other bacteria, is a member of the large CarD_TRCF family of bacterial proteins that interact with RNA polymerase. Structural analyses of the 164-residue M. xanthus CdnL by NMR is complicated because of broadening, and hence overlap, of the signals due to the self-association and the monomer-dimer equilibrium that occurs in solution. Here, we report (1)H, (13)C and (15)N assignments for CdnL achieved by analyzing its NMR spectra on the basis of the complete assignment obtained in this study for the 68-residue N-terminal fragment of CdnL (CdnLNt) together with those we described previously for the stable, protease-resistant, 110-residue C-terminal domain (CdnLCt). This approach relied on our observation that many of the CdnLNt and CdnLCt chemical shifts matched closely with those of the equivalent residues in the full-length protein. Our assignments provide the crucial first step in the structural analysis of CdnL and this functionally important family of bacterial proteins.