Small-molecule control of neurotransmitter sulfonation

Ian Cook, Mary Cacace, Ting Wang, Kristie Darrah, Alexander Deiters, Thomas S. Leyh

Research output: Contribution to journalArticlepeer-review

Abstract

Controlling unmodified serotonin levels in brain synapses is a primary objective when treating major depressive disorder—a disease that afflicts 20% of the world’s population. Roughly 60% of patients respond poorly to first-line treatments and thus new therapeutic strategies are sought. To this end, we have constructed isoform-specific inhibitors of the human cytosolic sulfotransferase 1A3 (SULT1A3)—the isoform responsible for sulfonating 80% of the serotonin in the extracellular brain fluid. The inhibitor design includes a core ring structure, which anchors the inhibitor into a SULT1A3-specific binding pocket located outside the active site, and a side chain crafted to act as a latch to inhibit turnover by fastening down the SULT1A3 active-site cap. The inhibitors are allosteric, they bind with nanomolar affinity and are highly specific for the 1A3 isoform. The cap-stabilizing effects of the latch can be accurately calculated and are predicted to extend throughout the cap and into the surrounding protein. A free-energy correlation demonstrates that the percent inhibition at saturating inhibitor varies linearly with cap stabilization — the correlation is linear because the rate-limiting step of the catalytic cycle, nucleotide release, scales linearly with the fraction of enzyme in the cap-open form. Inhibitor efficacy in cultured cells was studied using a human mammary epithelial cell line that expresses SULT1A3 at levels comparable with those found in neurons. The inhibitors perform similarly in ex vivo and in vitro studies; consequently, SULT1A3 turnover can now be potently suppressed in an isoform-specific manner in human cells.

Original languageEnglish (US)
Article number100094
JournalJournal of Biological Chemistry
Volume296
DOIs
StatePublished - Jan 1 2021

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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