LanV, a Bifunctional Enzyme: Aromatase and Ketoreductase during Landomycin A Biosynthesis

Abstract

LanV is involved in the biosynthesis of landomycin A. The exact function of this enzyme was elucidated with combinatorial biosynthesis by using Streptomyces fradiae mutants that produce urdamycin A. After expression of lanV in S. fradiae DeltaurdM, which is a mutant that accumulates rabelomycin, urdamycinon B and urdamycin B were found to be produced by the strain. This result indicates that LanV is involved in the 6-ketoreduction of the angucycline core, which preceeds a 5,6-dehydration reaction. 9-C-D-Olivosyltetrangulol was also produced by this strain; this demonstrates that LanV catalyses the aromatization of ring A of the angucycline structure. Coexpression of lanV and lanGT2 in S. fradiae AO, a mutant that lacks all four urdamycin glycosyltransferases, resulted in the production of tetrangulol and the glycoside landomycin H, both of which have an aromatic ring A. As glycosylated angucyclines were not observed after expression of lanGT2 in the absence of lanV, we conclude that LanGT2 needs an aromatized ring A for substrate recognition.

Cytotoxic Angucycline Class Glycosides from the Deep Sea Actinomycete Streptomyces lusitanus SCSIO LR32

“…9 We found that when this strain was fermented using modified-RA medium and the extract was analyzed by HPLC-DAD-UV, an array of secondary metabolites with UV spectra characteristic of the angucycline class of antibiotics was observed. 10,11 In this paper, we report the fermentation, isolation, and structure elucidation of five new angucycline C-glycosides, grincamycins B−F (1−5), from S. lusitanus SCSIO LR32 along with the previously reported grincamycin (6). Moreover, we report the cytotoxicities of compounds 1−6 against the human cancer cell lines HepG2, SW-1990, HeLa, NCI-H460, and MCF-7 and the mouse melanoma cell line B16.…”

Cloning and Characterization of a Gene Cluster for Hatomarubigin Biosynthesis in Streptomyces sp. Strain 2238-SVT4

“…The hrbI gene resembles lanV, a 6-ketoreductase gene in landomycin biosynthesis (12), and is assignable to the same function (Fig. 5).…”

Artificial Reconstruction of Two Cryptic Angucycline Antibiotic Biosynthetic Pathways

“…Recently, enzymes that employ such "substrate-assisted" catalysis have been characterised from other aromatic poly-A C H T U N G T R E N N U N G ketide biosynthesis pathways. [17,46,47] Moreover, unusual bifunctionality has been observed with enzymes that catalyse angucycline post-PKS reactions, [21,22] supporting the high inherent reactivity of the substrates. Finally, the lack of sequence-tofunction correlation with angucycline monooxygenases indicates that their function cannot be deduced in silico and suggests that gene products from the other unknown clusters (AlpF and Aur1I) might encode novel activities.…”

“…Therefore it is likely that CabV and the reductase domain of PgaM catalyse 2,3-dehydration in a manner similar to that seen in landomycin biosynthesis, where it has been suggested that aromatisation of the A-ring occurs through the action of a homologous reductase lanV. [21] According to sequence analyses the angucycline reductases are most closely related to SDR dehydrogenases. [43,44] However, the so called "extended SDR superfamily" does contain members that use the same conserved tyrosine residue in the active site for dehydration reactions, [43,45] which gives support to the 2,3-dehydration function assigned here.…”

“…[20] The most common post-PKS gene products found in angucycline gene clusters are similar to proteins from two well known enzyme families: FAD-dependent oxygenases and short chain alcohol dehydrogenase/reductases (SDRs). [21][22][23] Studying reactions catalysed by these post-PKS enzymes has been shown to be a challenging task, as most modifications of 1 lead to various possible rearrangements of the polyaromatic carbon skeleton and/or to shunt products. [24,25] We have recently detected, cloned and sequenced two cryptic angucycline-type gene clusters by using hybridisation probes generated with the DNA fingerprinting method.…”