Structure of a novel O-GlcNAc transferase GtfA reveals insights into the glycosylation of pneumococcal serine-rich repeat adhesins [Glycobiology and Extracellular Matrices]

June 16th, 2014 by Shi, W.-W., Jiang, Y.-L., Zhu, F., Yang, Y.-H., Shao, Q.-Y., Yang, H.-B., Ren, Y.-M., Wu, H., Chen, Y., Zhou, C.-Z.

Protein glycosylation catalyzed by the O-GlcNAc transferase (OGT) plays a critical role in various biological processes. In Streptococcus pneumoniae, the core enzyme GtfA and co-activator GtfB form an OGT complex to glycosylate the serine-rich repeat (SRR) of adhesin PsrP, which is involved in the infection and pathogenesis. Here we report the 2.0-Å crystal structure of GtfA, revealing a β-meander add-on domain beyond the catalytic domain. It represents a novel add-on domain, which is distinct from the all-α tetratricopeptide repeats in the only two structure-known OGTs. Structural analyses combined with binding assays indicate that this add-on domain contributes to forming an active GtfA-GtfB complex and recognizing the acceptor protein. In addition, the in vitro glycosylation system enables us to map the O-linkages to the serine residues within the first SRR of PsrP. These findings suggest that fusion with an add-on domain might be a universal mechanism for diverse OGTs that recognize varying acceptor proteins/peptides.
  • Posted in Journal of Biological Chemistry, Publications
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