Vibriobactins

Domain skipping biosynthesis of myxochromides Vibriobactin biosynthesis Iterative module use coelichelin biosynthesis Noncanonical Features of NRPSs Initiation Modules... 

Figure 6 Nonlinear synthetases, (a) Organization of the NRPS responsible for myxochromide A2 and myxochromide Si biosynthesis. The myxochromide Si synthetase contains an inactive module 4. (b) Biosynthesis of vibriobactin by the two-module vibriobactin synthetase.

Another set of unusual C domains include those that catalyze the formation of more than one amide bond on an acceptor substrate containing multiple amine moieties. For example, the C domain of the NRPS module FscI in fuscachelin biosynthesis likely catalyzes amide bond formation at both the a- and -amines of a PCP-bound L-hOrn intermediate. Other domains displaying similar activity include the condensation domain of MxcG, the third C domain of CchH, and the second C domain of VibF from the biosynthetic pathways for myxochelin, coelichelin, and vibriobactin, respectively. 

In a limited number of NRPSs, the final module terminates in a specialized C domain that catalyzes chain release through amide bond formation. Modules of this type are found in the synthetases involved in the biosynthesis of enniatin, vibriobactin, cyclosporin/ HC-toxin/ and PF1032A. Unlike TE termination, this method of chain release does not utilize an acyl-ester intermediate. Most likely, the chain termination precursor is presented to the C domain as an aminoacyl-5-PCP substrate. Most of these specialized C domains... 

Fluvibactin (Fig. 13, 45) from Vibrio fluvialis (391) differs from agrobactin by replacement of spermidine by norspermidine. Also here the precursor with a free central NH group could be isolated. Vibriobactin from Vibrio cholerae (Fig. 14,46) contains two cyclized DHB-Thr substituents (129). Syntheses of agrobactin, fluvibactin and vibriobactin are published (26, 30, 308). In vulnibactin from Vibrio vulnificus (Fig. 14, 47) (264) two DHB groups are replaced by salicylic acid units. The precursor with a free central NH group was also found. 

Bergeron RJ, Garlich JR, McManis JS (1985) Total Synthesis of Vibriobactin. Tetrahedron 41 507... 

Griffiths GL, Sigel SP, Payne SM, Neilands JB (1984) Vibriobactin, a Siderophore from Vibrio cholerae. J Biol Chem 10 383... 

Sakakura A, Umemura S, Ishihara K (2008) Convergent Total Syntheses of Fluvibactin and Vibriobactin Using Molybdenum(vi) Oxide-catalyzed Dehydrative Cyclization as a Key Step. Chem Commun 3561... 

Dihydroxybenzoate Containing Siderophores Enterobactin and Derivatives, Myxochelin A and Vibriobactin... 

A comparison of siderophores that have been both totally biosynthesized and chemically synthesized reveals that the more structurally simple compounds (pyo-chelin, myxochelin) can be synthesized following a biomimetic route, whereas more complex molecules (yersiniabactin, enterobactin, vibriobactin) often tend to... 

FIGURE 7.3 Other marine siderophores, including alterobactins, pseudoalterobactins, aerobactin, petrobactins, and vibriobactins. (Adapted from Vraspir Butler, 2009. NIH Public Access.)... 

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