2de4 | pdb_00002de4
Crystal structure of DSZB C27S mutant in complex with biphenyl-2-sulfinic acid
Structural highlights
FunctionDSZB_RHOSG Catalyzes the third and final step of the '4S' desulfurization pathway that removes covalently bound sulfur from dibenzothiophene (DBT) without breaking carbon-carbon bonds. Oxidizes 2-(2'-hydroxyphenyl)benzene sulphinate (HBPS) to 2-hydroxybiphenyl (HBP) plus sulfite (PubMed:31545606, PubMed:7574582, PubMed:7961424, PubMed:9308179, PubMed:9634856). The rate-limiting step of the '4S' desulfurization pathway (PubMed:31545606, PubMed:9308179). The pathway substrate specificity has been augmented using mutagenesis, however no mutations allowed use of alkylated thiophenes (PubMed:11823208).[1] [2] [3] [4] [5] [6] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe desulfurization of dibenzothiophene in Rhodococcus erythropolis is catalyzed by two monooxygenases, DszA and DszC, and a desulfinase, DszB. In the last step of this pathway, DszB hydrolyzes 2'-hydroxybiphenyl-2-sulfinic acid into 2-hydroxybiphenyl and sulfite. We report on the crystal structures of DszB and an inactive mutant of DszB in complex with substrates at resolutions of 1.8A or better. The overall fold of DszB is similar to those of periplasmic substrate-binding proteins. In the substrate complexes, biphenyl rings of substrates are recognized by extensive hydrophobic interactions with the active site residues. Binding of substrates accompanies structural changes of the active site loops and recruits His(60) to the active site. The sulfinate group of bound substrates forms hydrogen bonds with side chains of Ser(27), His(60), and Arg(70), each of which is shown by site-directed mutagenesis to be essential for the activity. In our proposed reaction mechanism, Cys(27) functions as a nucleophile and seems to be activated by the sulfinate group of substrates, whereas His(60) and Arg(70) orient the syn orbital of sulfinate oxygen to the sulfhydryl hydrogen of Cys(27) and stabilize the negatively charged reaction intermediate. Cys, His, and Arg residues are conserved in putative proteins homologous to DszB, which are presumed to constitute a new family of desulfinases. Crystal structure and desulfurization mechanism of 2'-hydroxybiphenyl-2-sulfinic acid desulfinase.,Lee WC, Ohshiro T, Matsubara T, Izumi Y, Tanokura M J Biol Chem. 2006 Oct 27;281(43):32534-9. Epub 2006 Aug 4. PMID:16891315[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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