|CATH domain||Related DB codes (homologues)|
|22.214.171.1240 : Rossmann fold||S00527,S00547,S00548,S00550,S00554,S00555,S00671,S00672,S00676,S00680,S00682,S00913,S00914,S00301,S00302,S00303,S00304,S00307,S00308,S00305,S00306,S00310,S00311,M00114,M00199,D00129,D00130,D00540,M00186|
|Protein name||Bile salt sulfotransferase||bile-salt sulfotransferaseBAST Ibile acid:3'-phosphoadenosine-5'-phosphosulfate sulfotransferasebile salt:3'phosphoadenosine-5'-phosphosulfate:sulfotransferasebile acid sulfotransferase Iglycolithocholate sulfotransferase|
|Synonyms||EC 126.96.36.199Hydroxysteroid SulfotransferaseHSTDehydroepiandrosterone sulfotransferaseDHEA-STST2ST2A3|
NM_003167.3 (DNA/RNA sequence)
|Activity||3''-phosphoadenylyl sulfate + glycolithocholate = adenosine 3'',5''-bisphosphate + glycolithocholate 3-sulfate.,3''-phosphoadenylyl sulfate + taurolithocholate = adenosine 3'',5''-bisphosphate + taurolithocholate sulfate.|
|Compound table: links to PDB-related databases & PoSSuM|
|Compound||3'-Phosphoadenylylsulfate||Glycolithocholate||Taurolithocholate||Adenosine 3',5'-bisphosphate||Sulfoglycolithocholate||Taurolithocholate sulfate|
|Type||amine group,nucleotide,sulfate group||amide group,carbohydrate,carboxyl group,steroid||amide group,carbohydrate,steroid,sulfonate group||amine group,nucleotide||amide group,carboxyl group,steroid,sulfate group||amide group,steroid,sulfonate group,sulfate group|
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|References for Catalytic Mechanism|
|References||Sections||No. of steps in catalysis|
|Journal||Trends Biochem Sci|
|Authors||Kakuta Y, Pedersen LG, Pedersen LC, Negishi M|
|Title||Conserved structural motifs in the sulfotransferase family.|
|Authors||Pedersen LC, Petrotchenko EV, Negishi M|
|Title||Crystal structure of SULT2A3, human hydroxysteroid sulfotransferase.|
|Journal||Arch Biochem Biophys|
|Authors||Negishi M, Pedersen LG, Petrotchenko E, Shevtsov S, Gorokhov A, Kakuta Y, Pedersen LC|
|Title||Structure and function of sulfotransferases.|
|According to the literature , the catalytic mechanism is proposed as follows:|
(1) The conserved histidine (His99) can be a general base that abstracts the proton from the acceptor hydroxy group, thereby converting this group to a strong nuceophile.
(2) The activated hydroxyl oxygen makes a nucleophilic attacks on the sulfur atom of PAPS, which in turn leads to an accumulation of negative charge at the bridging oxygen (i.e., leaving oxygen) between the 5'-phosphate and sulfate.
(3) On the other hand, the conserved lysine (Lys44) residue may act as a general acid to donate its proton to the bridging oxygen (as a stabilizer), thereby assisting in the dissociation of the sulfate group from PAPS. This catalytic lysine must also stabilize the transient state in aiding the dissociation of the sulfate from the PAPS.
(3') The conserved serine residue (Ser129) seems to regulate the sulfur transfer reaction as the switch for the catalytic lysine, through its interaction. The sidechain coordination of the serine residue (Ser129) to the catalytic lysine occurs subsequently to the binding of the 3'-phosphate of PAPS to this serine. Whereas the serine interacts with the lysine to decrease the PAPS hydrolysis, the sidechain nitrogen of the lysine must be coordinated with the bridging oxygen to play a role as catalytic acid.
(4) The histidine residue (His99) acts as a general acid to protonate the transferred sulfuryl group.
Taken together, the conserved histidine (His99) may play the major role in the switch as the catalytic base. Following the substrate binding, the histidine removes the proton from the acceptor group, making it the nucleophile that subsequently attacks the sulfur atom of the PAPS molecule. Negative charge accumulates on the bridging oxygen. Finally, the developing negative charge forces the sidechain nitrogen of the catalytic lysine to switch from the serine to the bridging oxygen and the sulfate dissociation occurs .