6h43 | pdb_00006h43

Flavin-dependent Tryptophan 6-halogenase Thal

spinqualitylabelsall models 6h43, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6h43 is a 2 chain structure with sequence from Atcc 23875. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: GOL, K, PO4 Related: 6ib5 Gene: thal (ATCC 23875) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed 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 A resolution. The structure revealed that the C6 of tryptophan is positioned next to the ε-amino group of a conserved lysine, confirming the hypothesis that proximity to the catalytic residue determines the site of electrophilic 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 Trp by the Thal-RebH5 variant resembled that of wildtype 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. Structure-based switch of regioselectivity in the flavin-dependent tryptophan 6-halogenase Thal.,Moritzer AC, Minges H, Prior T, Frese M, Sewald N, Niemann HH J Biol Chem. 2018 Dec 17. pii: RA118.005393. doi: 10.1074/jbc.RA118.005393. PMID:30559288 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

Proteopedia Page Contributors and Editors (what is this?)

OCA