Substrate-induced conformational changes in Escherichia coli taurine/alpha-ketoglutarate dioxygenase and insight into the oligomeric structure.
The enzymes in the alpha-ketoglutarate (alphaKG) dependent dioxygenase superfamily represent the largest class of non-heme iron oxidases and have important medical, ecological, and biotechnological roles. One such enzyme, taurine/alpha-ketoglutarate dioxygenase (TauD), catalyzes the conversion of 2-aminoethanesulfonate (taurine) to sulfite and aminoacetaldehyde while decomposing alphaKG to succinate and CO(2). This alphaKG dependent dioxygenase is expressed in Escherichia coli under sulfur starvation conditions and allows the cell to utilize taurine, and other similar sulfonates in the environment, as an alternative sulfur source. In this work, we report the structures of the apo and holo forms of TauD to 1.9 A resolution (R(cryst) = 21.2%, R(free) = 24.9%) and 2.5 A resolution (R(cryst) = 22.5%, R(free) = 27.8%), respectively. The models reported herein provide significant new insight into the substrate orientations at the active site and the conformational changes that are induced upon taurine binding. Furthermore, analysis of our crystallographic data coupled with reanalysis of the crystallographic model (resolution = 3.0 A, R(cryst) = 28.1, R(free) = 32.0) presented by Elkins et al. (Biochemistry (2002) 41, 5185-5192) reveals an alternative oligomeric arrangement for the enzyme that is consistent with the conserved primary and secondary structure elements of other alphaKG dependent dioxygenases.
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA.
Jessica R
JR
O'Brien
David J
DJ
Schuller
Victoria S
VS
Yang
Bret D
BD
Dillard
William N
WN
Lanzilotta
D001051:Apoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D007501:Iron / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D013379:Substrate Specificity; D013654:Taurine / Q000378:metabolism
D001051:Apoenzymes; D013654:Taurine; D007501:Iron; D006899:Mixed Function Oxygenases; C433064:taurine-alpha-ketoglutarate dioxygenase