Crystal structure of human cholesterol sulfotransferase (SULT2B1b) in the presence of pregnenolone and 3'-phosphoadenosine 5'-phosphate. Rationale for specificity differences between prototypical SULT2A1 and the SULT2BG1 isoforms.
The gene for human hydroxysteroid sulfotransferase (SULT2B1) encodes two peptides, SULT2B1a and SULT2B1b, that differ only at their amino termini. SULT2B1b has a predilection for cholesterol but is also capable of sulfonating pregnenolone, whereas SULT2B1a preferentially sulfonates pregnenolone and only minimally sulfonates cholesterol. We have determined the crystal structure of SULT2B1a and SULT2B1b bound to the substrate donor product 3'-phosphoadenosine 5'-phosphate at 2.9 and 2.4 A, respectively, as well as SULT2B1b in the presence of the acceptor substrate pregnenolone at 2.3 A. These structures reveal a different catalytic binding orientation for the substrate from a previously determined structure of hydroxysteroid sulfotransferase (SULT2A1) binding dehydroepiandrosterone. In addition, the amino-terminal helix comprising residues Asp19 to Lys26, which determines the specificity difference between the SULT2B1 isoforms, becomes ordered upon pregnenolone binding, covering the substrate binding pocket.
Lee
Karen A
KA
Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
Fuda
Hirotoshi
H
Lee
Young C
YC
Negishi
Masahiko
M
Strott
Charles A
CA
Pedersen
Lars C
LC
D000244:Adenosine Diphosphate / Q000378:metabolism*; D001224:Aspartic Acid; D001665:Binding Sites; D002784:Cholesterol / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D003687:Dehydroepiandrosterone / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D006860:Hydrogen Bonding; D007527:Isoenzymes / Q000737:chemistry; D008239:Lysine; D008958:Models, Molecular; D015394:Molecular Structure; D011284:Pregnenolone / Q000378:metabolism*; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins; D013379:Substrate Specificity; D015238:Sulfotransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D001224:Aspartic Acid; D003687:Dehydroepiandrosterone; D000244:Adenosine Diphosphate; D011284:Pregnenolone; D002784:Cholesterol; C010840:adenosine 3'-phosphate-5'-phosphate; D015238:Sulfotransferases; C433248:SULT2B1 protein, human; C028152:alcohol sulfotransferase; D008239:Lysine