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Structure of human POFUT2: insights into thrombospondin type 1 repeat fold and O ‐fucosylation
Author(s) -
Chen ChunI,
Keusch Jeremy J,
Klein Dominique,
Hess Daniel,
Hofsteenge Jan,
Gut Heinz
Publication year - 2012
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2012.143
Subject(s) - classics , philosophy , history
Protein O ‐fucosylation is a post‐translational modification found on serine/threonine residues of thrombospondin type 1 repeats (TSR). The fucose transfer is catalysed by the enzyme protein O ‐fucosyltransferase 2 (POFUT2) and >40 human proteins contain the TSR consensus sequence for POFUT2‐dependent fucosylation. To better understand O ‐fucosylation on TSR, we carried out a structural and functional analysis of human POFUT2 and its TSR substrate. Crystal structures of POFUT2 reveal a variation of the classical GT‐B fold and identify sugar donor and TSR acceptor binding sites. Structural findings are correlated with steady‐state kinetic measurements of wild‐type and mutant POFUT2 and TSR and give insight into the catalytic mechanism and substrate specificity. By using an artificial mini‐TSR substrate, we show that specificity is not primarily encoded in the TSR protein sequence but rather in the unusual 3D structure of a small part of the TSR. Our findings uncover that recognition of distinct conserved 3D fold motifs can be used as a mechanism to achieve substrate specificity by enzymes modifying completely folded proteins of very wide sequence diversity and biological function.