Directed Biosynthesis of New Enniatins.

Combinatorial Mutasynthesis of Scrambled Beauvericins, Cyclooligomer Depsipeptide Cell Migration Inhibitors from Beauveria bassiana

“…[22,23,41,42] Mutasynthesis, applied here for the first time to fungal cyclooligomer depsipeptide biosynthesis, improves on this technique by eliminating the competing natural precursor and allows the uncontested incorporation of "mutasynthons". [27] Mutasynthesis is especially effective in simplifying product profiles for oligomer products such as beauvericin, in which alternative precursors compete to fill more than one A C H T U N G T R E N N U N G position in the product.…”

“…Mutasynthesis with the kivr knockout strain is comparable in principle to the utilization of d-Hiv analogues during in vitro reconstituted enzymatic synthesis of cyclooligomer depsipeptides. [33,35,41] Whereas in vitro enzymatic synthesis is not constrained by precursor uptake or cell toxicity issues, in vivo mutasynthesis is inherently scalable during fermentation and could provide high yields. [27] Importantly, however, both of these approaches are limited by the inherent substrate specificity and tolerance of the NRPS enzyme involved.…”

Revisiting the enniatins: a review of their isolation, biosynthesis, structure determination and biological activities

“…Once formed, the dipeptidol unit condenses with two other dipeptidols in an iterative fashion to form a linear hexadepsipeptide, which cyclizes in the final step to form the enniatin. 24 ESyn has low substrate specificity for L-amino acids, thus permitting incorporation of different amino acids and contributing to the chemical diversity of the enniatins (Figure 1). Despite variability in the amino acid units, distinct Fusarium strains seem to incorporate preferentially some amino acids over others, as evidenced by the fact that certain enniatins can be isolated from only a particular species or strain of fungus.…”

“…Although the enniatin synthases were mentioned to have low substrate specificity for L-amino acids, a study also showed that this enzyme preferentially incorporates only certain sizes of amino acid side chains. 24 Thus, alanine and α-aminobutyric acid are the only other amino acids shown to be incorporated into a naturally produced enniatin, specifically enniatins J 1 ( 17 ), J 2 ( 18 ), J 3 ( 19 ) and K 1 ( 20 ). 14 In summary, if the enniatin will not form crystals suitable for X-ray analysis, NMR spectroscopy may be the best solution, although the spectrum will appear crowded and overlapped in certain diagnostic regions.…”

Peptide Synthesis without Ribosomes

“…It has also been experimentally demonstrated that the spectrum of NRPs made by a particular fungus in vivo, or by a particular syntheta se in vitro, can be easily altered by chang ing the composition of the available amino acid pool. There are many examples of such "directed biosynthesis" of novel NRPs, including penicillins, cyclosporins, enniatin s, ergopeptines, and others (e.g., Mach and Tatum, 1964;Traber et al, 1989;Lawen and Traber, 1993;Baldwin et al, 1994;Riederer et al, 1996;Krause et al, 2001). The ease with which novel NRPs can be made simply by feeding alternate amino acids indicates that NRP synthetas e modules have intrinsically low substrate specificity.…”