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Reevaluation of the Violacein Biosynthetic Pathway and its Relationship to Indolocarbazole Biosynthesis
Author(s) -
Sánchez César,
Braña Alfredo F.,
Méndez Carmen,
Salas José A.
Publication year - 2006
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.200600029
Subject(s) - biosynthesis , gene cluster , chromobacterium violaceum , biochemistry , gene , biology , escherichia coli , indole test , quorum sensing , virulence
The biosynthetic pathways for violacein and for indolocarbazoles (rebeccamycin, staurosporine) include a decarboxylative fusion of two tryptophan units. However, in the case of violacein, one of the tryptophans experiences an unusual 1→2 shift of the indole ring. The violacein biosynthetic gene cluster was previously reported to consist of four genes, vioABCD . Here we studied the violacein pathway through expression of vio genes in Escherichia coli and Streptomyces albus . A pair of genes ( vioAB ), responsible for the earliest steps in violacein biosynthesis, was functionally equivalent to the homologous pair in the indolocarbazole pathway ( rebOD ), directing the formation of chromopyrrolic acid. However, chromopyrrolic acid appeared to be a shunt product, not a violacein intermediate. In addition to vioABCD , a fifth gene ( vioE ) was essential for violacein biosynthesis, specifically for production of the characteristic 1→2 shift of the indole ring. We also report new findings on the roles played by the VioC and VioD oxygenases, and on the origin of violacein derivatives of the chromoviridans type.