Function of lanI in regulation of landomycin A biosynthesis in Streptomyces cyanogenus S136 and cross-complementation studies with Streptomyces antibiotic regulatory proteins encoding genes

Abstract

The transcriptional regulator of landomycin A biosynthesis encoded by lanI gene has been inactivated within the chromosome of Streptomyces cyanogenus S136. The obtained mutant strain did not produce landomycin A and its known intermediates. Loss of landomycin A production caused significant changes in morphology of the lanI deficient strain. RT-PCR analysis confirmed complete cessation of transcription of certain lan genes, including lanJ (encoding putative proton dependent transporter) and lanK (presumably involved in lanJ expression regulation). Introduction of either lanI or lndI [lanI homologue controlling landomycin E biosynthesis in Streptomyces globisporus 1912, both encoding Streptomyces antibiotic regulatory proteins (SARPs)] restored landomycin A production in the mutant strain. Chimeric constructs ladI and ladR were generated by exchanging the DNA sequences corresponding to N- and C-terminal parts of LndI and LanI. None of these genes were able to activate the production of landomycins in regulatory mutants of S. cyanogenus and S. globisporus. Nevertheless, the production of novel unidentified compound was observed in the case of S. cyanogenus harboring ladI gene. Various genes encoding SARPs have been expressed in S. globisporus and S. cyanogenus regulatory mutants and the results of these complementation experiments are discussed.

Properties of lanK-based regulatory circuit involved in landomycin biosynthesis in Streptomyces cyanogenus S136

“…Gene lanI encodes a positive pathway-specific regulator of landomycin A biosynthetic genes, particularly those which are targets for LanK negative regulation [20]. The significance of positive regulation exerted by LanI upon lanK -dependent genes remained ambiguous, since the absence of lanJ transcription in lanI -deficient S. cyanogenus mutant (ΔlanI7) could be explained either by absence of landomycins A and B directly responsible for abolishment of LanK repressing function, or by strict dependence of lanJ expression on LanI.…”

“…For this purpose actinophage φC31-based plasmid pMO19 has been constructed (see Materials and Methods) in which coding region of lanI has been placed under control of inducible tipA promoter ( tipAp ). We verified pMO19 via its introduction into lanI deficient S. cyanogenus strain ΔlanI7 [20] and induction of lanI expression with thiostrepton (15 ng/ml). The pMO19 + ΔlanI7 strain overproduced landomycin A, showing that pMO19 carries functionally proficient lanI gene.…”

Molecular Regulation of Antibiotic Biosynthesis in Streptomyces

“…Likewise, deletion of phoP causes reduced ACT and RED production under phosphate limitation (82). Another PhoP-repressible gene encodes RpoZ, the omega [69]), Aur1P (auricin, Streptomyces aureofaciens [297]), LanI (landomycins, Streptomyces cyanogenus [298]), and LndI (landomycin E, Streptomyces globisporus [299]). Bottom, NarI family: RedZ (undecylprodigiosin, S. coelicolor [67,68]), DnrN (daunorubicin, Streptomyces peucetius [209]), NcnR (naphthocyclinone, Streptomyces arenae [300]), VioR (tuberactinomycin, Streptomyces vinaceus [301]), and SCO1654 (protein of S. coelicolor with unknown function).…”

Autoregulation of antibiotic biosynthesis by binding of the end product to an atypical response regulator

“…Interestingly, homologues of jadR1 are present in the biosynthetic clusters for several angucycline antibiotics (29,30) and for antibiotics that contain an angucycline-like structure (31,32). The amino acid sequence conservation of such JadR1 homologues may indicate that they have a similar ligandinteractive specificity.…”