Biosynthesis of the Putative Siderophore Erythrochelin Requires Unprecedented Crosstalk between Separate Nonribosomal Peptide Gene Clusters

Abstract

The genome of the erythromycin-producing bacterium Saccharopolyspora erythraea contains many orphan secondary metabolite gene clusters including two (nrps3 and nrps5) predicted to govern biosynthesis of nonribosomal peptide-based siderophores. We report here the production by S. erythraea, even under iron-sufficient conditions, of a 2,5-diketopiperazine siderophore candidate we have named erythrochelin. Deletion of the nonribosomal peptide synthetase (NRPS) gene ercD within the nrps5 cluster abolished erythrochelin production. The tetrapeptide backbone of erythrochelin (alpha-N-acetyl-delta-N-acetyl-delta-N-hydroxyornithine-serine-delta-N-hydroxyornithine-delta-N-acetyl-delta-N-hydroxyornithine) suggests an orthodox colinear model for erythrochelin assembly. Curiously, the delta-N-acetyltransferase required for erythrochelin biosynthesis is encoded within a remote NRPS-cluster (nrps1) whose own NRPS contains an inactivating mutation. Disruption of the nrps1 gene mcd abolished erythrochelin biosynthesis, which could then be restored by addition of synthetic L-delta-N-acetyl-delta-N-hydroxyornithine, confirming an unprecedented example of functional crosstalk between nrps clusters.

Nonribosomal Peptide Synthetase Genes pesL and pes1 Are Essential for Fumigaclavine C Production in Aspergillus fumigatus

“…The current understanding of NRP synthetases and secondary metabolite gene clusters might need to be reconsidered in light of the findings and ideas presented here, and the current paradigm may not be as straightforward as "one NRP synthetase, one peptide" as has previously been found for NRPS in other pathways (e.g., gliotoxin biosynthesis) (3,12). Moreover, the notion of cluster cross talk is beginning to emerge with the confirmation of interactions between two separate NRP synthetases involved in siderophore biosynthesis in a bacterial species (25). More recently, cross talk was identified between two SM clusters on different chromosomes in A. nidulans (4).…”

Strategies for the Design and Discovery of Novel Antibiotics using Genetic Engineering and Genome Mining

“…erythraea (Robbel et al 2010). The same natural product was purified and then characterized by a bioassay-based fractionation following its antibiotic activity against Microccocus luteus or Bacillus subtilis (Lazos et al 2010). Another recently developed phenotype-based approach has been used for the identification of novel peptide anti-infective agents such as arylomycin ( Fig.…”

Tentative biosynthetic pathways of some microbial diketopiperazines

“…These domains are the adenylation domain (A), the peptidyl carrier protein domain (T), and the condensation domain (C) (Schwarzer et al 2003). Cyclodipeptides can be formed by dedicated NRPSs, as in brevianamide F (23 ) (Maiya et al 2006), erythrochelin (Lazos et al 2010), ergotamine (24) (Correia et al 2003), roquefortine C (García-Estrada et al 2011), acetylaszonalenin (Yin et al 2009), thaxtomin A (Healy et al 2000), GT (Balibar and Walsh 2006), or sirodesmin PL (Gardiner et al 2004) biosynthesis. Alternatively, cyclodipeptides can be formed by NRPSs during the synthesis of longer peptides, as truncated side products, as in cyclo(D-Phe-L-Pro) (25) or cyclomarazine A (26) biosynthesis (Gruenewald et al 2004;Schultz et al 2008;Schwarzer et al 2001).…”

“…Cyclo(L-Phe-L-Pro) (2) and cyclo(L-Phe-trans-4-OH-L-Pro) (3) are antifungal compounds (Ström et al 2002). Erythrochelin (4 ), coprogen (5), and dimerumic acid (6) are siderophores (Lazos et al 2010;Oide et al 2006;Wilhite et al 2001). Roquefortine C (7 ) and acetylaszonalenin (8 ) are mycotoxins (García-Estrada et al 2011;Yin et al 2009).…”