The 2,8-linked polysialic acid (polySia) glycotope is involved in cell migration and cell adhesion and thus plays a central role in the regulation of mammalian developmental processes. It is also an important tumor-associated oncodevelopmental antigen on a number of human cancers. On neurotropic E. coli K1 and Neisseria meningitidis Gp.B, the polySia capsule is a neurovirulent determinant associated with neonatal meningitis in humans. Therefore, it is important to understand the molecular mechanism of polySia chain synthesis, and how synthesis is controlled. These are the long-term objectives of our studies. The enzymes responsible for synthesis of polySia ar the CMP-Sia: 2,8 polysialytransferase (polySTs), designated PST and STX in mammals and NeuS in E. coli K1. There is no primary sequence homology between the mammalian and bacterial polySTs, yet all three catalyze synthesis of identical polySia chains. A key hypothesis to be tested is that PST, STX and NeuS achieve the same catalytic functions by rearranging conserved amino acid motifs spatially in their active sites to bind CMP-Sia and initiate polySia chain synthesis while bound to the enzyme.
The Specific Aims of this grant are three-fold.
Aim 1 will characterize by biochemical methods the length of the polySia chains synthesized by membrane-bond and soluble constructs of PST and STX derived from transfected N-CAM(+) and (-) cells. The nature of the potential reducing terminus in N-CAM (-)/polySia(+) transfected cells will als be determined.
Aim 2 includes structure-function studies that will investigate the structural basis for polysialylation. Active site cysteine and conserved basic amino acid motifs implicated in catalysis and processivity will be studied by site-directed mutagenesis.
Aim 3 will use in vitro reconstitution experiments to determine, """"""""how many enzymes does it take to synthesize polySia?"""""""". Successful completion of these studies will provide basic information for understanding the molecular mechanism of polysialylation, and the critical domains of the polySTs involved. This will also have important implications for basic studies relating to neural development and plasticity, neoplastic disease and molecular microbiology and pathogenesis, and provide a necessary framework for future studies.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM055703-04
Application #
6386682
Study Section
Pathobiochemistry Study Section (PBC)
Program Officer
Marino, Pamela
Project Start
1998-05-01
Project End
2004-04-30
Budget Start
2001-05-01
Budget End
2004-04-30
Support Year
4
Fiscal Year
2001
Total Cost
$306,284
Indirect Cost
Name
University of California Davis
Department
Biochemistry
Type
Schools of Medicine
DUNS #
094878337
City
Davis
State
CA
Country
United States
Zip Code
95618
Park, Kyoung Ho; Yeo, Sang Won; Troy 2nd, Frederic A (2014) Expression of polysialylated neural cell adhesion molecules on adult stem cells after neuronal differentiation of inner ear spiral ganglion neurons. Biochem Biophys Res Commun 453:282-7
Nakata, Daisuke; Zhang, Lirong; Troy 2nd, Frederic A (2006) Molecular basis for polysialylation: a novel polybasic polysialyltransferase domain (PSTD) of 32 amino acids unique to the alpha 2,8-polysialyltransferases is essential for polysialylation. Glycoconj J 23:423-36
Zhou, Guo-Ping; Troy 2nd, Frederic A (2005) NMR studies on how the binding complex of polyisoprenol recognition sequence peptides and polyisoprenols can modulate membrane structure. Curr Protein Pept Sci 6:399-411
Nakata, Daisuke; Troy 2nd, Frederic A (2005) Degree of polymerization (DP) of polysialic acid (polySia) on neural cell adhesion molecules (N-CAMS): development and application of a new strategy to accurately determine the DP of polySia chains on N-CAMS. J Biol Chem 280:38305-16
Zhou, Guo-Ping; Troy 2nd, Frederic A (2005) NMR study of the preferred membrane orientation of polyisoprenols (dolichol) and the impact of their complex with polyisoprenyl recognition sequence peptides on membrane structure. Glycobiology 15:347-59
Zhou, Guo-Ping; Troy 2nd, Frederic A (2003) Characterization by NMR and molecular modeling of the binding of polyisoprenols and polyisoprenyl recognition sequence peptides: 3D structure of the complexes reveals sites of specific interactions. Glycobiology 13:51-71
Sato, C; Fukuoka, H; Ohta, K et al. (2000) Frequent occurrence of pre-existing alpha 2-->8-linked disialic and oligosialic acids with chain lengths up to 7 Sia residues in mammalian brain glycoproteins. Prevalence revealed by highly sensitive chemical methods and anti-di-, oligo-, and poly-Sia ant J Biol Chem 275:15422-31