Figure 1.
Identification of Congocidine (1), Distamycin (2), and a novel pyrrolamide compound (3) in S. netropsis.
(A) High resolution mass spectrum of Congocidine and Distamycin. (B) Precursor ion scan-directed mass spectrum to identify compound 3. Base peak chromatograms of precursor ion scan are shown. Ions of m/z 273 and 247 are daughter ions of compound 3, and were used as the queries.
Figure 2.
Structural elucidation of Compound 3.
High resolution mass spectrum and MS/MS patterns of 3 is shown.
Figure 3.
Identification of the novel pyrrolamide compounds 4 (A), 5 (B), 6 (C), and 7 (D).
High resolution mass spectrum and MS/MS patterns of each compound are shown.
Figure 4.
Organization of the pyrrolamides biosynthesis-related genes identified from S. ambofaciens (a congocidine producer) and S. netropsis.
The deduced functions of each gene are summarized in Table S1 in File S1. Homologies in sequence are indicated by plain and dashed lines (the latter pattern is for the separate gene cluster).
Figure 5.
In-frame deletion of pya25 and pya26 in S. netropsis.
HPLC analysis of pyrrolamides production in S. netropsis wild-type strain, the mutant strains WDY002 (Δpya25) and WDY003 (Δpya26), and the complementation strains WDY004 (negative control) and WDY005. Congocidine, Compound 3, and Distamycin are indicated. The characteristic absorbance wave-length for pyrrolamides is 297 nm.
Figure 6.
Illustration of the “iterative strategy” underlying pyrrolamide biosynthesis.
The putative amidohydrolase Pya25 catalyzed the deacetylation of PCP-tethered pyrrolamide biosynthesis intermediates and determined the number of the pyrrole groups assembled into various pyrrolamides. A, adenylation domain; C, condensation domain; PCP, peptidyl carrier protein.