Protein sialylation has
been closely linked to many diseases including Alzheimer’s disease (AD) and is
broadly implicated in therapeutics in a terminal structure-sensitive manner.
However, how sialylation structurally affects mature glycoproteins and how such
effect is linked biochemically to AD progression largely remain ill-defined and
are, likely beset with the lack of appropriate strategies capable of rapid and
in situ manipulation of sialic acids on mature glycoproteins. Herein, we report
the use of native ion mobility-mass spectrometry (IM-MS)-based structural probing
methodology, enabling well-controlled, synergistic and in situ manipulation of mature
glycoproteins and attached sialic acids. Cell viability experiments and IM-MS
suggest that the dysregulating effects of transferrin sialylation on the
iron-enhanced Aβ cytotoxicity acts through sialylation-dependent Aβ and iron
co-importing pathway. Meanwhile, native gel electrophoresis and IM-MS reveal
the sialylation-regulated transferrin dimerization tendency. Collectively, IM-MS
is adapted to capture key sialylation intermediates involved in fine-tuning
AD-associated glycoprotein structural micoheterogeneity. Our results may shed
new lights on AD-modifying strategies based on sialylation-regulated
glycoprotein functions and cytotoxicity.
In situ analysis of intact proteins by ion mobility mass spectrometry
