Flavia Marinelli

In 1973, Eli Lilly and Company described the filamentous actinomycete producing the glycopeptide antibiotic A477 as an Actinoplanes species on the basis of its morphological and physiological features and deposited it as NRRL 3884 T . In this paper, we report that the phylogenetic analysis based on the 16S rRNA gene sequence and the whole genome phylogenomic study indicate that NRRL 3884 T forms a distinct monophyletic line within the genus Actinoplanes , being most closely related to Actinoplanes octamycinicus NBRC 14524 T [99.6 % 16S rRNA gene similarity, 89.4 % average nucleotide identity (ANI), 46.0 % digital DNA–DNA hybridization (dDDH)] and Actinoplanes ianthinogenes NBRC 13996 T (98.8 % 16S rRNA gene similarity, 89.0 % ANI, 47.0 % dDDH). NRRL 3884 T forms an extensively branched, non-fragmented vegetative mycelium; either sterile aerial hyphae or regular subglobose sporangia are formed depending on cultivation conditions. The cell wall contains meso -2,6-diaminopimelic acid and 2,6-diamino-3-hydroxypimelic acid and the diagnostic sugars are glucose, mannose and ribose with a minor amount of rhamnose. The predominant menaquinone (MK) is MK-9(H 4 ), with minor amounts of MK-9(H 2 ), MK-9(H 6 ) and MK-9(H 8 ). Mycolic acids are absent. The diagnostic phospholipids are diphosphatidylglycerol and phosphatidylethanolamine. The major cellular fatty acids are anteiso-C 17 : 0 , iso-C 16 : 0 and iso-C 15 : 0 , with moderate amounts of anteiso-C 15 : 0 and iso-C 17 : 0 . The genomic G+C content is 71.5 mol%. Significant differences in the genomic, morphological, chemotaxonomic and biochemical data between NRRL 3884 T and the two most closely related Actinoplanes type strains clearly demonstrate that NRRL 3884 T represents a novel species of the genus <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http:

Teicoplanin and A40926 (natural precursor of dalbavancin) are clinically relevant glycopeptide antibiotics (GPAs) produced by Actinoplanes teichomyceticus NRRL B-16726 and Nonomuraea gerenzanensis ATCC 39727. Their biosynthetic enzymes are coded within large biosynthetic gene clusters (BGCs), named tei for teicoplanin and dbv for A40926, whose expression is strictly regulated by pathway-specific transcriptional regulators (PSRs), coded by cluster-situated regulatory genes (CSRGs). Herein, we investigated the “cross-talk” between the CSRGs from tei and dbv, through the analysis of GPA production levels in A. teichomyceticus and N. gerenzanensis strains, with knockouts of CSRGs cross-complemented by the expression of heterologous CSRGs. We demonstrated that Tei15* and Dbv4 StrR-like PSRs, although orthologous, were not completely interchangeable: tei15* and dbv4 were only partially able or unable to cross-complement N. gerenzanensis knocked out in dbv4 and A. teichomyceticus knocked out in tei15*, implying that the DNA-binding properties of these PSRs are more different in vivo than it was believed before. At the same time, the unrelated LuxR-like PSRs Tei16* and Dbv3 were able to cross-complement corresponding N. gerenzanensis knocked out in dbv3 and A. teichomyceticus knocked out in tei16*. Moreover, the heterologous expression of dbv3 in A. teichomyceticus led to a significant increase in teicoplanin production. Although the molecular background of these events merits further investigations, our results contribute to a deeper understanding of GPA biosynthesis regulation and offer novel biotechnological tools to improve their production.