Structural and functional role of disulphide bonds and substrate binding residues of the human beta-galactoside alpha-2,3-sialyltransferase 1 (hST3Gal1)

摘要: Overexpression of hST3Gal1 leads to hypersialylation cell-surface glycoconjugates, a cancer-associated condition that promotes cell growth, migration and invasion. Upregulation this enzyme in ovarian cancer is linked progression metastasis, contributing also chemotherapy resistance. Strategies for preventing metastasis include the inhibition hST3Gal1, which demands structure-based studies on its strict regioselectivity substrate/donor preference. Herein we describe contribution various residues constituting donor CMP-Neu5Ac acceptor Galβ1-3GalNAc-R binding sites catalysis. Removal hydrogen bonds and/or stacking interactions among substrates Y191, Y230, N147, S148 N170 affected enzyme’s activity different extent, revealing fine control needed an optimal catalytic performance. To gain further understanding correlation structure, stability, vitro role disulphide was analysed. As expected, disruption Glycosyltransferase family 29 (GT29) invariant bond C142-C281, as well ST3Gal1 subfamily conserved C61-C139 inactivates enzyme. While C59-C64 not essential function, absence reduces (kcat) about 67 72%, respectively, diminishes melting temperature (Tm) by 7 °C.