Effects of san7324 and san7324L disruption on morphological differentiation and nikkomycin production of Streptomyces ansochromogenes

Abstract:

[Objective] wblA disruption mutant of Streptomyces ansochromogenes fails to produce nikkomycin.RNA-seq and transcriptional analysis revealed that the san7324 could be transcribed normally in S.ansochromogenes(wild-type),whereas not transcribed in the wblA(a global regulatory gene) disruption mutant (ΔwblA).This research aims to reveal the function of san7324 in nikkomycin production.[Methods] To investigate the role of san7324 in nikkomycin biosynthesis,a san7324 disruption mutant was constructed via homologous recombination,and was subsequently confirmed by genetic complementation.The transcriptional levels of selected genes in the nikkomycin biosynthetic cluster were analyzed.[Results] The mutant (Δsan7324) lost ability to produce nikkomycin under the same culture conditions compared with the wild-type strain.Disruption of san7324L(a san7324 homologous gene) caused the decrease of nikkomycin production.However,when san7324 and san7324L were disrupted,the double mutant (Δsan7324-san7324L) failed to form grey spores or spore chains but conferred a white phenotype of aerial hyphae,and no nikkomycin production was observed in comparison with wild-type strain.In addition,the nikkomycin production and morphological differentiation could be restored by the complementation of san7324-san7324L in Δsan7324-san7324L.Further studies preliminarily indicated that disruption of san7324 and san7324L mainly affected the transcriptional level of pathway-specific regulatory gene sanG in nik cluster,affected the morphological differentiation and nikkomycin biosynthesis in S.ansochromogenes.[Conclusion] These results provided more evidence for investigating the relationship between morphological differentiation and physiological metabolism in Streptomyces,and lay the foundation for elucidating the regulatory mechanism of the pleiotropic regulatory gene wblA.