Structural basis for the broad substrate specificity of two acyl-CoA dehydrogenases FadE5 from mycobacteria.

Xiaobo Chen, Jiayue Chen, Bing Yan, Wei Zhang, Luke W Guddat, Xiang Liu, Zihe Rao

Proceedings of the National Academy of Sciences of the United States of America 2020 Jul 14

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FadE, an acyl-CoA dehydrogenase, introduces unsaturation to carbon chains in lipid metabolism pathways. Here, we report that FadE5 from Mycobacterium tuberculosis (MtbFadE5) and Mycobacterium smegmatis (MsFadE5) play roles in drug resistance and exhibit broad specificity for linear acyl-CoA substrates but have a preference for those with long carbon chains. Here, the structures of MsFadE5 and MtbFadE5, in the presence and absence of substrates, have been determined. These reveal the molecular basis for the broad substrate specificity of these enzymes. FadE5 interacts with the CoA region of the substrate through a large number of hydrogen bonds and an unusual π-π stacking interaction, allowing these enzymes to accept both short- and long-chain substrates. Residues in the substrate binding cavity reorient their side chains to accommodate substrates of various lengths. Longer carbon-chain substrates make more numerous hydrophobic interactions with the enzyme compared with the shorter-chain substrates, resulting in a preference for this type of substrate.

Citation

Xiaobo Chen, Jiayue Chen, Bing Yan, Wei Zhang, Luke W Guddat, Xiang Liu, Zihe Rao. Structural basis for the broad substrate specificity of two acyl-CoA dehydrogenases FadE5 from mycobacteria. Proceedings of the National Academy of Sciences of the United States of America. 2020 Jul 14;117(28):16324-16332