Analysis of an 8.1-kb DNA Fragment Contiguous with the Erythromycin Gene Cluster of Saccharopolyspora erythraea in the eryCI-Flanking Region

An 8.1-kb region of the Saccharopolyspora erythraea genome, significant for its contiguity to the known genes of the erythromycin biosynthetic gene cluster, was mutationally analyzed and its DNA sequence was determined. The region lies immediately adjacent to eryCI. The newly characterized region is notable for a large, 3.0-kb segment, predicted not to be translated, followed by four probable genes: an acetyltransferase gene, a protease inhibitor gene, a methyltransferase gene, and a transposase gene. Because the probable functions of the genes in this region are not required for erythromycin biosynthesis or resistance and because a deletion of a 6.0-kb portion of this region had no effect on erythromycin biosynthesis, this region marks the outside boundary of the erythromycin gene cluster. Therefore, eryCI represents the end of the cluster. These results complete the analysis of the erythromycin gene cluster and eliminate the possibility that additional sought-after pathway-specific structural or regulatory genes might be found within or adjacent to the cluster.