title: Structure of a novel O-linked N-acetyl-D-glucosamine (O-GlcNAc) transferase, GtfA, reveals insights into the glycosylation of pneumococcal serine-rich repeat adhesins.
abstract: 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 (pneumococcal serine-rich repeat protein), 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.
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Shi
authors.forename: Yong-Liang
authors.initials: YL
authors.lastname: Jiang
authors.forename: Fan
authors.initials: F
authors.lastname: Zhu
authors.forename: Yi-Hu
authors.initials: YH
authors.lastname: Yang
authors.forename: Qiu-Yan
authors.initials: QY
authors.lastname: Shao
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Yang
authors.forename: Yan-Min
authors.initials: YM
authors.lastname: Ren
authors.forename: Hui
authors.initials: H
authors.lastname: Wu
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Chen
authors.forename: Cong-Zhao
authors.initials: CZ
authors.lastname: Zhou
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D006031:Glycosylation; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D013296:Streptococcus pneumoniae / Q000201:enzymology* / Q000235:genetics; D000637:Transaminases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D009097:Multienzyme Complexes; D000637:Transaminases