Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2006 Jul;23(5-6):423-36.
doi: 10.1007/s10719-006-6356-5.

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

Affiliations

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

Daisuke Nakata et al. Glycoconj J. 2006 Jul.

Abstract

To determine the molecular basis of eukaryotic polysialylation, the function of a structurally unique polybasic motif of 32 amino acids (pI approximately 12) in the polysialyltransferases (polySTs), ST8Sia II (STX and ST8Sia IV (PST) was investigated. This motif, designated the "polysialyltransferase domain" (PSTD), is immediately upstream of the sialylmotif S (SM-S). PolyST activity was lost in COS-1 mutants in which the entire PSTD in ST8Sia IV was deleted, or in mutants in which 10 and 15 amino acids in either the N- or C- terminus of PSTD were deleted. Site-directed mutagenesis showed that Ile(275), Lys(276) and Arg(277) in the C-terminus of PSTD in ST8Sia IV, which is contiguous with the N-terminus of sialylmotif-S, were essential for polysialylation. Arg(252) in the N-terminus segment of the PSTD was also required, as was the overall positive charge. Thus, multiple domains in the polySTs can influence their activity. Immunofluorescent microscopy showed that the mutated proteins were folded correctly, based on their Golgi localization. The structural distinctness of the conserved PSTD in the polySTs, and its absence in the mono- oligoSTs, suggests that it is a "polymerization domain" that distinguishes a polyST from a monosialyltransferases. We postulate that the electrostatic interaction between the polybasic PSTD and the polyanionic polySia chains may function to tether nascent polySia chains to the enzyme, thus facilitating the processive addition of new Sia residues to the non-reducing end of the growing chain. In accord with this hypothesis, the polyanion heparin was shown to inhibit recombinant human ST8Sia II and ST8Sia IV at 10 microM.

PubMed Disclaimer

Similar articles

Cited by

References

    1. J Biol Chem. 2001 May 11;276(19):15696-703 - PubMed
    1. J Biol Chem. 1994 Apr 8;269(14):10330-40 - PubMed
    1. J Biol Chem. 2000 Jun 16;275(24):18594-601 - PubMed
    1. J Biol Chem. 1995 Jan 27;270(4):1497-500 - PubMed
    1. Methods Enzymol. 1994;230:460-84 - PubMed

Publication types

LinkOut - more resources