Introduction of Kanamycin Resistant Gene to Pock-forming Plasmid pSAl.1 of Streptomyces azureus and Identification of spolllE-like Gene in the Recombinant Plasmid

A plasmid, pSAl.1, of StrePtomyces a.zuyeus elicited conjugative pocks and inhibited the sporulation of its host mycelia. The analysis of plasmid pSA1.1 was hampered by the lack of selective marker. Therefore, the introduction of a kanamycin resistance gene (Fzmr) derived from Strefltomyces kanamyceticus to pSA1.1 was tried. The obtained recombinant still preserved the sporulation-inhibitory and pock-forming abilities and was able to confer kanamycin resistance on the host strain. The sporulation-inhibitory gene was studied by the use of one of these recombinants. The deletion analysis and sequencing of the derivative plasmid found an open reading frame (ORF909b) that was involved in sporulation-inhibitory function of pSA1.1 and in pock formation. The nucleotide sequences of ORF909b were compared with those of the genes registered in GenBank, but no similarity was found. However, the predicted amino acid sequence of ORF909b showed a significantly high similarity with that of the spo111E gene of Bacillus subtilis. This detected gene might be a new sporulation-regulatory gene in streptomycetes. The function of the detected gene on the sporulation-inhibition was also discussed.