Substrate gating confers steroid specificity to estrogen sulfotransferase

Evgeniy V. Petrotchenko, Mary E. Doerflein, Yoshimitsu Kakuta, Lars C. Pedersen, Masahiko Negishi

研究成果: Contribution to journalArticle査読

45 被引用数 (Scopus)

抄録

Estrogen sulfotransferase (EST) exhibits a high substrate specificity and catalytic efficiency toward estrogens such as estradiol (E2) but insignificant ability to sulfate hydroxysteroids such as dehydroepiandrosterone (DHEA). To provide the structural basis for this estrogen specificity, we mutated amino acid residues that constitute the substrate-binding site of EST. Among these mutants, only Tyr-81 decreased E2 and increased DHEA sulfotransferase activities. Substitution for Tyr-81 by smaller hydrophobic residues increased K(m(E2)) for E2 activity, whereas the k(cat(E2)) remained relatively constant. The Y81L mutant exhibited the same DHEA activity as wild-type hydroxysteroid sulfotransferase, for which K(m(DHEA)) remained relatively constant, and k(cat(DHEA)) was markedly increased. The side chain of Tyr-81 is directed at the A-ring of the E2 molecule in the substrate-binding pocket of EST, constituting a steric gate with Phe-142 sandwiching E2 from the opposite side. The present mutagenesis study indicates that the 3β-hydroxyl group of the DHEA molecule is excluded from the catalytic site of EST through steric hindrance of Tyr-81 with the C- 19 methyl group of DHEA. Thus, this stricture-like gating caused by steric hindrance appears to be a structural principle for conferring estrogen specificity to EST.

本文言語英語
ページ(範囲)30019-30022
ページ数4
ジャーナルJournal of Biological Chemistry
274
42
DOI
出版ステータス出版済み - 10 15 1999
外部発表はい

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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