Molecular basis of dimer formation during the biosynthesis of benzofluorene-containing atypical angucyclines

Abstract

Lomaiviticin A and difluostatin A are benzofluorene-containing aromatic polyketides in the atypical angucycline family. Although these dimeric compounds are potent antitumor agents, how nature constructs their complex structures remains poorly understood. Herein, we report the discovery of a number of fluostatin type dimeric aromatic polyketides with varied C−C and C−N coupling patterns. We also demonstrate that these dimers are not true secondary metabolites, but are instead derived from non-enzymatic deacylation of biosynthetic acyl fluostatins. The non-enzymatic deacylation proceeds via a transient quinone methide like intermediate which facilitates the subsequent C–C/C−N coupled dimerization. Characterization of this unusual property of acyl fluostatins explains how dimerization takes place, and suggests a strategy for the assembly of C–C and C–N coupled aromatic polyketide dimers. Additionally, a deacylase FlsH was identified which may help to prevent accumulation of toxic quinone methides by catalyzing hydrolysis of the acyl group.

Angucycline Glycosides from an Intertidal Sediments Strain Streptomyces sp. and Their Cytotoxic Activity against Hepatoma Carcinoma Cells

“…Though, the distinct in vivo toxicity restricted the further development of these compounds. Recently, an atypical angucycline, lomaiviticin A, was reported under preclinical evaluation for antitumor treatment due to its prominent cytotoxicity and effects of inducing double-strand breaks in DNA [14,23]. In this research, compounds 1-4 was assayed the cytotoxic activity against normal liver cell LO2 and hepatoma carcinoma cells HepG-2, SMMC-7721 and plc-prf-5 by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method (Table 2).…”

“…Although firstly discovered in half a century ago and possessing potent antibacterial, antiproliferative and cytotoxic activities [6][7][8][9][10][11], so far none of angucycline compounds has been successfully developed into clinical drug due to toxicity or solubility issues, which is unlike to its biogenetic relatives tetracycline and anthracycline groups [2]. Recent researches on this group mainly concentrated on the understanding of biosynthetic mechanisms, so as to obtain modified analogues with medicinal potentiality through genetic manipulation [12][13][14].…”

Chimeric 6‐methylsalicylic acid synthase with domains of acyl carrier protein and methyltransferase from Pseudallescheria boydii shows novel biosynthetic activity

“…The gene with a 6200 bp ORF and harbouring KS‐AT‐DH‐KR‐ACP domains in the protein sequence was successfully and heterologously expressed with PPTase in Escherichia coli and Saccharomyces cerevisiae (Wattanachaisaereekul et al ., ; Lee et al ., ; Bond et al ., ). Moreover, 6MSA, as an intermediate, may play a role in the polyketide biosynthesis of other structurally diverse compounds with comparable differences in biological activities (Holm et al ., ; Huang et al ., ; Kong et al ., ). The enzyme is regarded as a multifunctional catalytic machine and operates sequentially in individual active sites to yield a polyketide product.…”

Marine Bacterial Aromatic Polyketides From Host-Dependent Heterologous Expression and Fungal Mode of Cyclization

“…Fluostatins (FSTs) are a growing family of atypical angucycline-type APKs and display antibacterial, antitumor and peptidase inhibition activities (Akiyama et al, 1998a , b ; Baur et al, 2006 ; Feng et al, 2010 ; Zhang et al, 2012 ; Yang et al, 2015 ; Jiang et al, 2017 ; Zhang W. et al, 2017 ; Huang et al, 2018 ; Jin et al, 2018 ). Recently, heterologous expression of the type II PKS gene cluster ( fls ) of FSTs from South China Sea-derived Micromonospora rosaria SCSIO N160 in Streptomyces coelicolor YF11 (Zhou et al, 2012 ) enabled the production of new FST derivatives (Yang et al, 2015 ).…”

“…Recently, heterologous expression of the type II PKS gene cluster ( fls ) of FSTs from South China Sea-derived Micromonospora rosaria SCSIO N160 in Streptomyces coelicolor YF11 (Zhou et al, 2012 ) enabled the production of new FST derivatives (Yang et al, 2015 ). Intriguingly, introduction of the fls -gene cluster in Streptomyces albus J1074 led to production of diverse C–C and C–N coupled dimeric FSTs (Huang et al, 2018 ). Herein we report the discovery of APKs derived from different chain lengths and cyclization patterns in the heterologous host S. albus J1074.…”