Cloned gene encoding the delta subunit of Bacillus subtilis RNA polymerase

Core RNA polymerase and several forms of RNA polymerase holoenzyme from Bacillus subtilis are found in association with a 21,500-kDa polypeptide called delta (delta). We have cloned the structural gene (rpoE) for delta by using a hybridization probe a synthetic oligodeoxynucleotide that was designed on the basis of a partial NH2-terminal amino acid (aa) sequence of purified delta protein. The rpoE gene was found to encode a 173-aa polypeptide of a predicted Mr of 20,400. Genetic and physical mapping experiments placed rpoE at 325 degrees on the B. subtilis chromosome and established the gene order rpoE-ctrA-spo0F. The delta subunit is known to enhance the specificity of transcription in vitro by bacterial and phage SP01-modified forms of polymerase, but replacement of rpoE by an in vitro-constructed deletion-mutated gene was found not to impair viability, sporulation, or the growth of phage SP01.