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Catalytic Site Atlas

CSA LITERATURE entry for 1os7

E.C. nametaurine dioxygenase
SpeciesEscherichia coli (Bacteria)
E.C. Number (IntEnz) 1.14.11.17
CSA Homologues of 1os7
CSA Entries With UniProtID P37610
CSA Entries With EC Number 1.14.11.17
PDBe Entry 1os7
PDBSum Entry 1os7
MACiE Entry M0129

Literature Report

IntroductionTaurine:alpha-ketoglutarate dioxygenase (TauD) hydroxylates C1 of taurine (2-aminoethane-1-sulfonic acid) and other organosulfates, leading to elimination of sulfite and thereby initiating the acquisition of sulphur from compounds that contain the element in a form that would otherwise be biologically inert. E. coli expresses TauD only in the absence of sulfate. The reaction requires molecular dioxygen and 2-oxoglutarate as a cosubstrate.
Mechansim1) In the resting state, Fe(II) is coordinated by His99, Asp 101, His 255 and three water molecules.
2) The cosubstrate 2-oxoglutarate binds to Fe(II) via the carbonyls on C1 and C2, displacing two water molecules. Taurine binds (not to Fe(II)), displacing the third water molecule.
3) Dioxygen binds to Fe(II) via one of the oxygen atoms; this formally oxidises iron to Fe(III).
4) The radical on the O-O bond attacks C2 of 2-oxoglutarate, with the C2 carbonyl attacking and oxidising iron to Fe(IV).
5) The cosubstrate is decarboxylated with C1 leaving as carbon dioxide. This is concomitant with heterolytic O-O bond cleavage and oxidation of the cosubstrate, giving an Fe(IV)=O oxoferryl intermediate with bound succinate.
6) The oxo atom abstracts the taurine C1 hydrogen in a radical mechanism, with reduction of iron to Fe(III)-OH, leaving a radical on taurine.
7) The taurine radical is hydroxylated with OH to give 1-hydroxytaurine, with reduction of iron to Fe(II), regenerating the initial oxidation state.
8) 1-hydroxytaurine decomposes to give sulfite and aminoacetaldehyde.
Arg 270 changes its hydrogen bonding to the cosubstrate during the reaction, and may initiate the decarboxylation step or help to remove carbon dioxide from the metal coordination sphere.
Reaction

Catalytic Sites for 1os7

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
ArgA270270macie:sideChainArg 270 hydrogen bonds to the cosubstrate, and may initiate decarboxylation, or the leaving of carbon dioxide from the iron coordination sphere.

Annotated By Reference To The Literature - Site 2 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
ArgB270270macie:sideChainArg 270 hydrogen bonds to the cosubstrate, and may initiate decarboxylation, or the leaving of carbon dioxide from the iron coordination sphere.

Annotated By Reference To The Literature - Site 3 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
ArgC270270macie:sideChainArg 270 hydrogen bonds to the cosubstrate, and may initiate decarboxylation, or the leaving of carbon dioxide from the iron coordination sphere.

Annotated By Reference To The Literature - Site 4 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
ArgD270270macie:sideChainArg 270 hydrogen bonds to the cosubstrate, and may initiate decarboxylation, or the leaving of carbon dioxide from the iron coordination sphere.

Literature References

Notes:Ascorbate increases the reaction rate. The mechanism of this is not known, but has been proposed to be via the prevention of oxidative self-inactivation.
Price JC
Kinetic dissection of the catalytic mechanism of taurine:alpha-ketoglutarate dioxygenase (TauD) from Escherichia coli.
Biochemistry 2005 44 8138-8147
PubMed: 15924433
M├╝ller I
Crystal structure of the alkylsulfatase AtsK: insights into the catalytic mechanism of the Fe(II) alpha-ketoglutarate-dependent dioxygenase superfamily.
Biochemistry 2004 43 3075-3088
PubMed: 15023059
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