Heterologous Expression Leads to Discovery of Diversified Lobophorin Analogues and a Flexible Glycosyltransferase

Abstract

The heterologous expression of the lobophorin biosynthetic gene cluster from marine-derived Streptomyces pactum SCSIO 02999 has led to the discovery of new analogues that carry d-kijanose (or its variants with a 3-amino or hydroxyl group) at C-9. The identification of intermediates resulting from the inactivation of lobG1 (encoding C-17 kijanosyltransferase) and lobG3 (encoding C-9 digitoxosyltransferase) demonstrates the substrate flexibility of LobG3 to also accept d-kijanose and its variants. Notably, two lobophorins with d-kijanose at C-9 show improved bioactivities.

Marine natural products

“…New Streptomyces -sourced MNPs included the antimicrobial adipostatins E–J 100–105 , several of which inhibit coenzyme-A biosynthesis, 33 N -(12-methyl-10-oxobutyl)- l -tyrosine methyl ester 106 , 34 antimicrobial lavandulylated flavonoids 107 and 108 from a sponge-derived actinomycete, 35 meijiemycin 109 , 36 and youssoufenes 110–114 , that resulted from genetic manipulation of an aminotransferase family gene that activated production of these metabolites. 37 Heterologous expression studies of Streptomyces pactum led to a diverse series of lobophorin analogues 115–122 , 38 whilst other investigations afforded new napyradiomycin analogues 123–127 , 39 tetrahydroanthra-γ-pyrone antibiotics given the trivial names shellmycins A–D 128–131 , 40 borrelidins M–O 132–134 , 41 cytotoxic and rearranged angucyclinone derivatives named donghaecyclinones A–C 135–137 , 42 and a rare diketopiperazine glycoside 138 . 43 Chemical investigations of Streptomyces albogriseolus identified eunicellin diterpenoids microeunicellol A 139 and B 140 , which are structurally similar to terpenoids isolated from the gorgonian Muricella sibogae , 44 while other studies yielded two new medermycin derivatives, lactoquinomycins C 141 and D 142 (ref.…”

Integrated Metabolomic–Genomic Workflows Accelerate Microbial Natural Product Discovery

“…Analogues can be formed with heterologous expression of BGCs, as seen with verticilactams, as well as after deletion or alteration of enzymatic domains within BGCs and subsequent expression, as seen with the BGCs for complestatin and lobophorin. , Therefore, after synthetic biology experiments, a molecular network can be used to visualize the biocombinatorial chemical space through uploading the tandem mass spectral data of the metabolites produced by the wild type producer and those that arise from the synthetic biology experiments. A direct comparison can be performed that includes confirmation of contribution to nodes that represent the compound(s) of interest and an evaluation of new nodes that may appear within a compound cluster, indicating new analogues.…”

N-oxygenation of amino compounds: Early stages in its application to the biocatalyzed preparation of bioactive compounds

“…This nitro-sugar is part of the spirotetronate antibiotic kijanimicin, which in addition to its antitumor activity, has proven activity against anaerobes, Grampositive bacteria and malaria's parasite, Plasmodium falciparum. Moreover, a recent research work characterized the presence of D-kijanose in new lobophorin analogues with improved bioactivity (Tan et al, 2020). Because of its overall fold and despite the low aminoacidic sequence homology (17% to 26%) KijD3 belongs to the acyl-CoA dehydrogenase superfamily as a member of the class D flavin dependent monooxygenases which depends on a separate flavin reductase for the supply of reduced flavin (either FAD or FMN) as the cofactor (Singh et al, 2012).…”