Structural Basis of Cyclic 1,3-Diene Forming Acyl-Coenzyme A Dehydrogenases |
| |
Authors: | Dr Johannes W Kung Anne-Katrin Meier Dr Max Willistein Dr Sina Weidenweber Ulrike Demmer Dr Ulrich Ermler Prof?Dr Matthias Boll |
| |
Affiliation: | 1. Faculty of Biology – Microbiology, Albert-Ludwigs-Universität Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany;2. Max-Planck-Institute for Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt, Germany |
| |
Abstract: | The biologically important, FAD-containing acyl-coenzyme A (CoA) dehydrogenases (ACAD) usually catalyze the anti-1,2-elimination of a proton and a hydride of aliphatic CoA thioesters. Here, we report on the structure and function of an ACAD from anaerobic bacteria catalyzing the unprecedented 1,4-elimination at C3 and C6 of cyclohex-1-ene-1-carboxyl-CoA (Ch1CoA) to cyclohex-1,5-diene-1-carboxyl-CoA (Ch1,5CoA) and at C3 and C4 of the latter to benzoyl-CoA. Based on high-resolution Ch1CoA dehydrogenase crystal structures, the unorthodox reactivity is explained by the presence of a catalytic aspartate base (D91) at C3, and by eliminating the catalytic glutamate base at C1. Moreover, C6 of Ch1CoA and C4 of Ch1,5CoA are positioned towards FAD-N5 to favor the biologically relevant C3,C6- over the C3,C4-dehydrogenation activity. The C1,C2-dehydrogenation activity was regained by structure-inspired amino acid exchanges. The results provide the structural rationale for the extended catalytic repertoire of ACADs and offer previously unknown biocatalytic options for the synthesis of cyclic 1,3-diene building blocks. |
| |
Keywords: | acyl-CoA dehydrogenases enzyme catalysis flavins fatty acid oxidation oxidoreductases |
|
|