Download Functional and structural relationship of Cst-II sialyltransferases to synthesize mono- and di-sialylated lipo-oligosaccharides derivatives

Title of Project :
Functional and structural relationship of Cst-II
sialyltransferases to synthesize mono- and disialylated lipo-oligosaccharides derivatives
Name of
Supervisor :
Prof. Nobuhiro Yuki
Contact Details:
Department of Medicine/Microbiology
Level 9, MD6, 14th Medical Drive,
NUS, Singapore – 117599.
Telephone no: 65161092.
Email: [email protected]
Short Description
Sialyltransferases are enzymes responsible for the transfer of sialic acid to the
terminal nascent oligosaccharides. The sialyltransferase in Campylobacter
jejuni (Cst-II) is capable of transferring sialic acid moiety from cytidine-5monophospho-N-acetyl-neuraminic acid (CMP-NeuAc) to the terminal position
of lipo-oligosaccharides (LOS), thus mimicking the human ganglioside. There
are two Cst-II isoforms that has either mono functional (α2,3-sialyltransfearse)
or bi functional (α2,3- and α2,8-sialyltransferase) activity. These synthesize
different types of gangliosides-like LOS that give rise to different phenotypes
of autoimmune diseases.
We propose to elucidate structural basis of mono- and bi- functional
sialyltransferase activity of Cst-II enzyme and also to obtain novel
sialyltransferases that are able to synthesize specific oligosaccharides.
The techniques involved in this project would be: recombinant DNA
technology and 2-stage site directed mutagenesis, protein expression and
detection techniques, kinetic assay and capillary electrophoresis to determine
the enzymatic activity of novel Cst-II.
On completion of the project, the elucidation of Cst-II molecular mechanism
would be helpful in understanding similar enzyme that synthesizes cellsurface glyco-conjugates resulting in autoimmune diseases. The identification
of the catalytic residues would enable us to design inhibitors that limit the
bacterial ability to synthesize ganglioside-like LOS thus preventing immune
evasion.