Atomic coordinates and structure factors for the reported crystal structures have been deposited with the Protein Data Bank under PDB IDs 4JVM for the SULT1E1-PAPTBBPA structure, 4JVN for the SULT1E1 PAP-3-OH-BDE-47 structure, and 4JVL for the SULT1E1-PAP-E2 structure.
To understand the binding and inhibition of estrogen sulfotransferase by BFRs, we obtained crystal structures of SULT1E1 in complex with the product cofactor PAP and three different compounds bound at the active site: the natural substrate (E2), a BFR (TBBPA), and a human BFR metabolite (3-OH-BDE-47) at resolutions of 1.
The crystal structure of human SULT1E1 with PAP and E2 bound to the active site (see Supplemental Material, Figures S1A,B and S2A) is similar in overall fold and substrate binding as previously determined for the mouse estrogen sulfotransferase (Kakuta et al.
The co-crystal structure of PAP and TBBPA bound to SULT1E1 reveals TBBPA binding in the same substrate binding pocket as E2.
Overall, the protein conformation of SULT1E1 with bound TBBPA is very similar to that with bound E2 with only a few minor changes in the substrate binding pocket.
The crystal structure of SULT1E1 with PAP and the BDE-47 metabolite 3-OH-BDE-47 bound reveals that the metabolite is bound to the same binding site as E2 and TBBPA (Figure 3; see also Supplemental Material, Figure S2C).
The 100,000g supernatant fractions of SULT1A1*1, SULT1A3, SULT1B1, and SULT1E1 were partially purified by chromatographic methods (Falany et al.
For SULT1A1*1 and -1A1*2, we used seven substrate concentrations in the range from 5 to 100 nM; for SULT1E1 we used six 3-OH-BaP concentrations from 15.
coli expressing SULT1A1*1, SULT1A3, SULT1B1, and SULT1E1, and the purchased Sf-9 cytosol fraction (PanVera, Madison, WI) containing SULT1A1*2.
SULT1A1*1 and SULT1E1 showed substrate inhibition at concentrations of 3-OH-BaP > 0.
For SULT1E1, compound A1 (6'-OHCB35) was a poor inhibitor of 3-OH-BaP sulfonation at either of the substrate concentrations studied (Table 3).
50] values with SULT1E1 showed a significant (p < 0.