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Referenztyp Zeitschriften
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Titel (primär) Structures of 2-Hydroxyisobutyric Acid-CoA ligase reveal determinants of substrate specificity and describe a multi-conformational catalytic cycle
Autor Zahn, M.; Kurteva-Yaneva, N.; Schuster, J.; Krug, U.; Georgi, T.; Müller, R.H.; Rohwerder, T.; Sträter, N.;
Journal / Serie Journal of Molecular Biology
Erscheinungsjahr 2019
Department UMB;
Band/Volume 431
Heft 15
Sprache englisch;
POF III (gesamt) T41;
Keywords X-ray crystal structure; catalytic cycle; domain alternation; domain rotation; ANL; superfamily
Abstract 2-Hydroxyisobutyric acid (2-HIBA) is a biomarker of adiposity and associated metabolic diseases such as diabetes mellitus. It is also formed in the bacterial degradation pathway of the fuel oxygenate methyl tert-butyl ether (MTBE), requiring thioesterification with CoA prior to isomerization to 3-hydroxybutyryl-CoA by B12-dependent acyl-CoA mutases. Here, we identify the adenylating enzymes superfamily member 2-HIBA-CoA ligase (HCL) in the MTBE-degrading bacterium Aquincola tertiaricarbonis L108 by knockout experiments. To characterize this central enzyme of 2-HIBA metabolism, ligase activity kinetics of purified HCL and its X-ray crystal structures were studied. We analyzed the enzyme in three states, which differ in the orientation of the two enzyme domains. A 154° rotation of the C-terminal domain accompanies the switch from the adenylate- into the thioester-forming state. Furthermore, a third conformation was obtained, which differs by 50° and 130° from the adenylation and thioesterification states, respectively. Phylogenetic and structural analysis reveals that HCL defines a new subgroup within phenylacetate-CoA ligases (PCLs) thus far described to exclusively accept aromatic acyl substrates. In contrast, kinetic characterization clearly demonstrated that HCL catalyzes CoA activation of several aliphatic short-chain carboxylic acids, preferentially 2-HIBA. Compared to the classical PCL representatives PaaK1 and PaaK2 of Burkholderia cenocepacia J2315, the acyl binding pocket of HCL is significantly smaller and more polar, due to unique active-site residues Y164 and S239 forming H-bonds with the OH-group of the acyl substrate moiety. Furthermore, HCL and PaaK topologies illustrate the evolutionary steps leading from a homodimeric to the fused monomeric core fold found in other ligases.
ID 21970
dauerhafte UFZ-Verlinkung http://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=21970
Zahn, M., Kurteva-Yaneva, N., Schuster, J., Krug, U., Georgi, T., Müller, R.H., Rohwerder, T., Sträter, N. (2019):
Structures of 2-Hydroxyisobutyric Acid-CoA ligase reveal determinants of substrate specificity and describe a multi-conformational catalytic cycle
J. Mol. Biol. 431 (15), 2747 - 2761