AdpA, a Positive Regulator for Morphological Development and Toyocamycin Biosynthesis in Streptomyces diastatochromogenes 1628.

AdpA is studied and considered as a pleiotropic regulator which is involved in morphological development and secondary metabolism in many Streptomyces. In this study, AdpA which was cloned from toyocamycin (TM)-producing strain Streptomyces diastatochromogenes 1628, was identified as an ortholog of AdpA and belongs to a large subfamily of the AraC/XylS family. In order to elucidate the correlation of AdpA with TM biosynthesis and morphological differentiation, adpA was placed under the control of the ermE* promoter in plasmid pIB139. By intergeneric conjugation, the resulting plasmid pIB139-adpA was introduced into mutant S. diastatochromogenes 1628-T62 that is defective in sporulation and had limited TM production as well as transcriptional level of gene adpA, yielding the recombinant strain S. diastatochromogenes 1628-T62A. As expected, due to over-expression of adpA, the S. diastatochromogenes 1628-T62A restored spore formation to a certain extent compared with control strain S. diastatochromogenes 1628-T62. Moreover, compared with control strain 1628-T62, the TM production of recombinant 1628-T62A was increased by 120.1% on 5 l fermenter. In addition, by using semi-quantitative reverse transcription-PCR analysis, we discovered that the transcriptional levels of gene adpA and the all toy genes involved in TM biosynthesis were elevated in recombinant 1628-T62A compared with S. diastatochromogenes 1628-T62. These results confirm that cloned adpA plays a positive role in TM biosynthesis and morphological differentiation.