Characterization of the Biosynthesis Gene Cluster for the Pyrrole Polyether Antibiotic Calcimycin (A23187) in Streptomyces chartreusis NRRL 3882

Abstract

The pyrrole polyether antibiotic calcimycin (A23187) is a rare ionophore that is specific for divalent cations. It is widely used as a biochemical and pharmacological tool because of its multiple, unique biological effects. Here we report on the cloning, sequencing, and mutational analysis of the 64-kb biosynthetic gene cluster from Streptomyces chartreusis NRRL 3882. Gene replacements confirmed the identity of the gene cluster, and in silico analysis of the DNA sequence revealed 27 potential genes, including 3 genes for the biosynthesis of the ␣-ketopyrrole moiety, 5 genes that encode modular type I polyketide synthases for the biosynthesis of the spiroketal ring, 4 genes for the biosynthesis of 3-hydroxyanthranilic acid, an N-methyltransferase tailoring gene, a resistance gene, a type II thioesterase gene, 3 regulatory genes, 4 genes with other functions, and 5 genes of unknown function. We propose a pathway for the biosynthesis of calcimycin and assign the genes to the biosynthesis steps. Our findings set the stage for producing much desired calcimycin derivatives using genetic modification instead of chemical synthesis.

Genome Mining of Streptomyces sp. Tü 6176: Characterization of the Nataxazole Biosynthesis Pathway

“…[ www.chembiochem.org 24340)t hat might be involved in the central metabolism shikimate pathway. NatAN shares similarity with orthologous enzymes involved in the biosynthesis of saphenamycin (EsmA5), [10] calcimycin (CalB1), [9] and tomaymycin( To mD and To mP). NatAN shares similarity with orthologous enzymes involved in the biosynthesis of saphenamycin (EsmA5), [10] calcimycin (CalB1), [9] and tomaymycin( To mD and To mP).…”

“…[9] Streptomyces sp. [9] In the enterobactin cluster there is also aDHHA dehydrogenase encoded by CF54_ 12685. A homologue of DHHA dehydrogenase NatDB is presenti nt he calcimycin biosynthesis pathway (CalB3).…”

“…Calcimycin is the mostc omplex naturalb enzoxazole as it is composed of three moieties:aspiroketal ring synthesized by at ype Ip olyketide synthase (PKS), an a-ketopyrrole derived from l-proline and modified by an on-ribosomal peptides ynthetase (NRPS), and ab enzoxazole unit whose precursori s3 -hydroxyanthranilic acid (3-HAA). [9] In the pyrrolobenzodiazepine sibiromycin biosynthesis pathway,3 -HAA derives from l-tryptophan,w hichi sm odified by the kynurenine pathway through the activity of ak ynurenine 3-monoxygenase, an aryl formamidase, at ryptophan-2,3dioxygenase, and ak ynurenine hydrolase. Structurally,N AT (1,S cheme 1) is formed from three moieties:t wo correspond to 3-HAA, and the third is 6-methylsalicylic acid (6-MSA).…”

The TetR Family of Regulators

“…TFRs are also present in the biosynthesis clusters for diverse polyketides, including ansamycins (e.g., rifQ in the rifamycin cluster [91]), macrolactams (e.g., mlaM in the ML-449 cluster [92]), and polyether ionophores (e.g., schR3 in the calcimycin cluster [93]). TFRs are not limited to polyketide biosynthesis clusters but are found in biosynthesis clusters for nonribosomal peptides (e.g., acmP and acmU in the actinomycin cluster [94]) and nucleoside antibiotics (e.g., amiP in the amicetin cluster [95]).…”

Genome Sequences of Three Tunicamycin-Producing Streptomyces Strains, S. chartreusis NRRL 12338, S. chartreusis NRRL 3882, and S. lysosuperificus ATCC 31396

“…S. clavuligerus NRRL 3585 also produces clavulinic acid (a lactamase inhibitor), cephalosporin-type antibiotics, and holomycin, and S. chartreusis strains also produce chartreusin and calcimycin (calcium ionophore A23187). Gene clusters that code for biosynthesis of these natural products have also been identified (9,6,12,14).…”