33468-35-8Relevant articles and documents
Targeted Enzyme Engineering Unveiled Unexpected Patterns of Halogenase Stabilization
Minges, Hannah,Schnepel, Christian,B?ttcher, Dominique,Wei?, Martin S.,Spro?, Jens,Bornscheuer, Uwe T.,Sewald, Norbert
, p. 818 - 831 (2019/12/24)
Halogenases are valuable biocatalysts for selective C?H activation, but despite recent efforts to broaden their application scope by means of protein engineering, improvement of thermostability and catalytic efficiency is still desired. A directed evoluti
Structure-based switch of regioselectivity in the flavin-dependent tryptophan 6-halogenase Thal
Moritzer, Ann-Christin,Minges, Hannah,Prior, Tina,Frese, Marcel,Sewald, Norbert,Niemann, Hartmut H.
, p. 2529 - 2542 (2019/03/12)
Flavin-dependent halogenases increasingly attract attention as biocatalysts in organic synthesis, facilitating environmentally friendly halogenation strategies that require only FADH2, oxygen, and halide salts. Different flavin-dependent tryptophan halogenases regioselectively chlorinate or brominate tryptophan’s indole moiety at C5, C6, or C7. Here, we present the first substrate-bound structure of a tryptophan 6-halogenase, namely Thal, also known as ThdH, from the bacterium Streptomyces albogriseolus at 2.55 ? resolution. The structure revealed that the C6 of tryptophan is positioned next to the -amino group of a conserved lysine, confirming the hypothesis that proximity to the catalytic residue determines the site of electro-philic aromatic substitution. Although Thal is more similar in sequence and structure to the tryptophan 7-halogenase RebH than to the tryptophan 5-halogenase PyrH, the indole binding pose in the Thal active site more closely resembled that of PyrH than that of RebH. The difference in indole orientation between Thal and RebH appeared to be largely governed by residues positioning the Trp backbone atoms. The sequences of Thal and RebH lining the substrate binding site differ in only few residues. Therefore, we exchanged five amino acids in the Thal active site with the corresponding counterparts in RebH, generating the quintuple variant Thal-RebH5. Overall conversion of L-Trp by the Thal-RebH5 variant resembled that of WT Thal, but its regioselectivity of chlorination and bromination was almost completely switched from C6 to C7 as in RebH. We conclude that structure-based protein engineering with targeted substitution of a few residues is an efficient approach to tailoring flavin-dependent halogenases.
An Unusual Flavin-Dependent Halogenase from the Metagenome of the Marine Sponge Theonella swinhoei WA
Smith, Duncan R. M.,Uria, Agustinus R.,Helfrich, Eric J. N.,Milbredt, Daniela,Van Pée, Karl-Heinz,Piel, J?rn,Goss, Rebecca J. M.
, p. 1281 - 1287 (2017/05/29)
Uncultured bacteria from sponges have been demonstrated to be responsible for the generation of many potent, bioactive natural products including halogenated metabolites.1 The identification of gene clusters from the metagenomes of such bacterial communities enables the discovery of enzymes that mediate new and useful chemistries and allows insight to be gained into the biogenesis of potentially pharmacologically important natural products. Here we report a new pathway to the keramamides (krm); the first functional evidence for the existence of a distinct producer in the Theonella swinhoei WA chemotype is revealed, and a key enzyme on the pathway, a unique flavin-dependent halogenase with a broad substrate specificity, with potential as a useful new biocatalytic tool, is described.
