Dehydroepiandrosterone sulphotransferase (DHEA-ST) is an enzyme that converts dehydroepiandrosterone (DHEA), and some other steroids, into their sulphonated forms. The enzyme catalyses the sulphonation of DHEA on the 3α-oxygen, with 3′-phosphoadenosine-5′-phosphosulphate contributing the sulphate. The structure of human DHEA-ST in complex with its preferred substrate DHEA has been solved here to 1.99Å using molecular replacement with oestradiol sulphotransferase (37% sequence identity) as a model. Two alternative substrate-binding orientations have been identified. The primary, catalytic, orientation has the DHEA 3α-oxygen and the highly conserved catalytic histidine in nearly identical positions as are seen for the related oestradiol sulphotransferase. The substrate, however, shows rotations of up to 30°, and there is a corresponding rearrangement of the protein loops contributing to the active site. This may also reflect the low identity between the two enzymes. The second orientation penetrates further into the active site and can form a potential hydrogen bond with the desulphonated cofactor 3′,5′-phosphoadenosine (PAP). This second site contains more van der Waal interactions with hydrophobic residues than the catalytic site and may also reflect the substrate-inhibition site. The PAP position was obtained from the previously solved structure of DHEA-ST co-crystallized with PAP. This latter structure, due to the arrangement of loops within the active site and monomer interactions, cannot bind substrate. The results presented here describe details of substrate binding to DHEA-ST and the potential relationship to substrate inhibition.
Research Article| May 08 2002
Crystal structure of human dehydroepiandrosterone sulphotransferase in complex with substrate
Peter H. REHSE;
Sheng-Xiang LIN 1
Oncology and Molecular Endocrinology Research Center, Laval University Medical Center CHUL (CHUQ), 2705 Boul. Laurier, Quebec City, Quebec, G1V 4G2 Canada
1To whom correspondence should be addressed (e-mail email@example.com).
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Peter H. REHSE, Ming ZHOU, Sheng-Xiang LIN; Crystal structure of human dehydroepiandrosterone sulphotransferase in complex with substrate. Biochem J 15 May 2002; 364 (1): 165–171. doi: https://doi.org/10.1042/bj3640165
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