New Alpiniamides From Streptomyces sp. IB2014/011-12 Assembled by an Unusual Hybrid Non-ribosomal Peptide Synthetase Trans-AT Polyketide Synthase Enzyme

Abstract

The environment of Lake Baikal is a well-known source of microbial diversity. The strain Streptomyces sp. IB2014/011-12, isolated from samples collected at Lake Baikal, was found to exhibit potent activity against Gram-positive bacteria. Here, we report isolation and characterization of linear polyketide alpiniamide A (1) and its new derivatives B–D (2–5). The structures of alpiniamides A–D were established and their relative configuration was determined by combination of partial Murata’s method and ROESY experiment. The absolute configuration of alpiniamide A was established through Mosher’s method. The gene cluster, responsible for the biosynthesis of alpiniamides (alp) has been identified by genome mining and gene deletion experiments. The successful expression of the cloned alp gene cluster in a heterologous host supports these findings. Analysis of the architecture of the alp gene cluster and the feeding of labeled precursors elucidated the alpiniamide biosynthetic pathway. The biosynthesis of alpiniamides is an example of a rather simple polyketide assembly line generating unusual chemical diversity through the combination of domain/module skipping and double bond migration events.

Characterization of Actinomycetes Strains Isolated from the Intestinal Tract and Feces of the Larvae of the Longhorn Beetle Cerambyx welensii

“…This antibiotic has an unexpected nonlinear synthesis that involves a hybrid polyketide synthase-nonribosomal peptide synthetase. It is assembled in two halves and is then ligated into the mature molecule [ 37 , 38 ]. Another compound produced by one of the isolated strains is the polyketide alteramide A.…”

Reclassification of Streptomyces fulvissimus as a later heterotypic synonym of Streptomyces microflavus

“…Closed circle, common in two strains; open circle, specific in each the strain; t1pks , type-I PKS gene cluster; t3pks , type-III PKS gene cluster; nrps , NRPS gene cluster; pks/nrps , hybrid PKS/NRPS gene cluster; THN, 1,3,6,8-tetrahydroxynaphthalene. Gene clusters whose products were predicted by bioinformatic analysis are boldfaced and shown as the gene names [27–38]. The products are in parentheses.…”

Heterologous expression of bacterial natural product biosynthetic pathways

“…70 The same approach has been used to discover new alpiniamide derivatives through heterologous expression. 71 Type II polyketide topoisomerase inhibitor pyxidicyclines (B 4) have been uncovered through a self-resistance guided genome mining approach and induced gene expression in the myxobacterial host Pyxidicoccus fallax An d48. The underlying BGC has been assembled and reorganized using the aforementioned PCR-based TAR cloning strategy to produce heterologous pyxidicyclines in the myxobacterial host strains Myxococcus xanthus DK1622 and Stigmatella aurantiaca DW4/3-1.…”