Xylosyltransferase I acceptor properties of fibroblast growth factor and its fragment bFGF (1–24)

• Published in: Biochemical and biophysical research communications 2005-07, Vol.333 (1), p.156-166
• Main Authors: Kuhn, Joachim, Schnölzer, Martina, Schön, Sylvia, Müller, Sandra, Prante, Christian, Götting, Christian, Kleesiek, Knut
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Basic fibroblast growth factor; Binding Sites; Enzyme Activation; Fibroblast Growth Factor 2 - chemistry; Heparin; Molecular Sequence Data; Pentosyltransferases - chemistry; Peptide Fragments - chemistry; Protein Binding; UDP Xylose-Protein Xylosyltransferase; Xylosyltransferase
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2005.05.087

Human basic fibroblast growth factor (bFGF) is a heparin-binding growth factor containing a G-S-G-motif which is a potential recognition sequence of xylosyltransferase I (XT-I). Here, we show that the recombinant human bFGF was xylosylated in vitro by human XT-I and that the fragment bFGF (1–24) is a good XT-I acceptor ( K m = 20.8 μM for native XT-I and K m = 22.3 μM for recombinant XT-I). MALDI and MALDI-PSD time-of-flight mass spectrometric analyses of the xylosylated bFGF protein demonstrate the transfer of xylose to the serine residue of the G-S-G-motif in the amino terminal end of bFGF. The peptide bFGF (1–24) is well suitable as an acceptor substrate for XT-I and can be used in a radiochemical assay to measure the XT-I activity in cell culture supernatant and human body fluids, respectively. Furthermore, we could demonstrate that the XT-I interacts strongly with heparin and that this glycosaminoglycan is a predominantly non-competitive inhibitor of the enzyme using the fragment bFGF (1–24) as xylose acceptor.