Transformation of the methylotrophic actinomycete Amycolatopis methanolica with plasmid DNA: stimulatory effect of a pMEA300-encoded gene.

Amycolatopsis methanolica contains a 13.29-kb plasmid (pMEA300) present both in the free state and integrated at a unique genomic location. A pMEA300-free derivative (strain WV1) was selected, allowing further analysis of pMEA300-encoded functions. Whole cells of strain WV1 could be transformed at high frequencies (approximately 10(6) transformants per microgram of plasmid DNA) with both circular and linear plasmid DNA, provided that the pMEA300-encoded stf (stimulation of transformation frequency) gene was present. stf would encode a putative protein of 373 amino acids with M(r) 40,201, resembling putative regulatory proteins involved in sporulation of Streptomyces griseus and Streptomyces coelicolor.