Nam7 Hydroxylase Is Responsible for the Formation of the Naphthalenic Ring in the Biosynthesis of Neoansamycins

Ten new benzenic ansamycins, 5,10-<i>seco</i>-neoansamycins A–J (<b>1</b>–<b>10</b>), were isolated from the <i>nam7</i>-disrupted mutant strain SR201<i>nam1</i>OEΔ<i>nam7</i>. These are the benzenic counterparts of the neoansamycins, which provide direct evidence that the putative hydroxylase Nam7 is involved in the formation of naphthalenic ring in neoansamycin biosynthesis and connect benzenic and naphthalenic ansamycins for the first time

Activating a Cryptic Ansamycin Biosynthetic Gene Cluster To Produce Three New Naphthalenic Octaketide Ansamycins with <i>n</i>‑Pentyl and <i>n</i>‑Butyl Side Chains

Genome mining is a rational approach to discovering new natural products. The genome sequence analysis of <i>Streptomyces</i> sp. LZ35 revealed the presence of a putative ansamycin gene cluster (<i>nam</i>). Constitutive overexpression of the pathway-specific transcriptional regulatory gene <i>nam1</i> successfully activated the <i>nam</i> gene cluster, and three novel naphthalenic octaketide ansamycins were discovered with unprecedented <i>n</i>-pentylmalonyl-CoA or <i>n</i>-butylmalonyl-CoA extender units. This study represents the first example of discovering novel ansamycin scaffolds via activation of a cryptic gene cluster

Juanlimycins A and B, Ansamycin Macrodilactams from <i>Streptomyces</i> sp.

Ansamycins are a family of macrolactams characterized by an aromatic chromophore with an aliphatic chain (<i>ansa</i> chain) connected back to a nonadjacent position through an amide bond. This family has shown a high degree of druggability exemplified by rifamycins, maytansinoids, and geldanamycins. In this study, the isolation of two novel ansamycin macrodilactams with unprecedented features, juanlimycins A (<b>1</b>) and B (<b>2</b>), from <i>Streptomyces</i> sp. LC6 were reported. The structures of <b>1</b> and <b>2</b> were assigned on the basis of analysis of NMR spectroscopic data and X-ray single crystal diffraction