CLONING AND CHARACTERIZATION OF PLANCTOMYCES-LIMNOPHILUS RPON - COMPLEMENTATION OF A SALMONELLA-TYPHIMURIUM RPON MUTANT STRAIN

The rpoN gene, which encodes the alternative sigma factor sigma(54), w as cloned from the budding, peptidoglycan-less bacterium Planctomyces limnophilus. P. limnophilus rpoN complemented the Ntr(-) phenotype of a Salmonella typhimurium rpoN mutant strain. The P. limnophilus rpoN g ene encoded a predicted polypeptide that was 495 residues in length an d shared a significant homology with ether members of the sigma(54) fa mily. The protein sequence displayed all of the characteristic motifs found in members of this family, including the C-terminal helix-turn-h elix motif and the well-conserved RpoN box. A potential sigma(54)-depe ndent activator was also identified in P. limnophilus. These findings extend the range of phylogenetic groups within the Domain Bacteria tha t are known to contain sigma(54). (C) 1998 Elsevier Science B.V. All r ights reserved.