6p00

Structural highlights

Function

[REBH_NOCAE] Involved in the biosynthesis of the indolocarbazole antitumor agent rebeccamycin. Catalyze the chlorination of tryptophan (Trp) at C7 position to yield 7-chlorotryptophan. The reaction between FADH2, Cl-, and O2 generates the powerful oxidant HOCl, which is presumed to carry out the chlorination reaction. The reaction of HOCl with the active site Lys-79 generates a lysine chloramine, which plays a key role in directing regiospecific chlorination of substrate in this important class of biosynthetic enzymes. It is also able to use bromide ions to generate monobrominated Trp.^{[1] [2] [3]}

References

1. ↑ Sanchez C, Butovich IA, Brana AF, Rohr J, Mendez C, Salas JA. The biosynthetic gene cluster for the antitumor rebeccamycin: characterization and generation of indolocarbazole derivatives. Chem Biol. 2002 Apr;9(4):519-31. PMID:11983340
2. ↑ Yeh E, Garneau S, Walsh CT. Robust in vitro activity of RebF and RebH, a two-component reductase/halogenase, generating 7-chlorotryptophan during rebeccamycin biosynthesis. Proc Natl Acad Sci U S A. 2005 Mar 15;102(11):3960-5. Epub 2005 Mar 2. PMID:15743914 doi:http://dx.doi.org/10.1073/pnas.0500755102
3. ↑ Yeh E, Blasiak LC, Koglin A, Drennan CL, Walsh CT. Chlorination by a long-lived intermediate in the mechanism of flavin-dependent halogenases. Biochemistry. 2007 Feb 6;46(5):1284-92. PMID:17260957 doi:10.1021/bi0621213