Paper

Structural and mechanistic characterization of bifunctional heparan sulfate N-deacetylase-N-sulfotransferase 1

Wu, Liang, Duyvesteyn, Helen M. E., Skidmore, Mark A., Owens, Raymond J., Mycroft-West, Courtney J., Gandhi, Neha S., Abdelkarim, Sahar

2023

Overview

Heparan sulfate (HS) polysaccharides are major constituents of the extracellular matrix, involved in myriad structural and signaling processes. Mature HS polysaccharides contain complex, non-templated patterns of sulfation and epimerization, which mediate interactions with diverse protein partners. Complex HS modifications form around initial clusters of glucosamine-N-sulfate (GlcNS) on nascent polysaccharide chains, but the mechanistic basis underpinning incorporation of the GlcNS modification itself into HS remains unclear. We have determined cryo-electron microscopy structures of human N-deacetylase-N-sulfotransferase (NDST)1, the bifunctional enzyme responsible for initial GlcNS modification of HS. Our structures reveal the architecture of both NDST1 deacetylase and sulfotransferase catalytic domains, alongside a previously unreported non-catalytic N-terminal domain. Surprisingly, the two catalytic domains of NDST1 adopt an unusual back-to-back topology that limits direct cooperativity. Binding analyses, aided by novel activity modulating nanobodies, suggest that sulfotransferase domain substrate anchoring initiates the NDST1 catalytic cycle, providing a plausible mechanism for cooperativity despite spatial domain separation. Our data shed light on key determinants of NDST1 activity, and describe tools to probe NDST1 function in vitro and in vivo.

• Publisher: Cold Spring Harbor Laboratory
• Subject: Biochemistry