The crystal structure of galacto-N-biose/lacto-N-biose I phosphorylase. A large deformation of a tim barrel scaffold

Masafumi Hidaka, Mamoru Nishimoto, Motomitsu Kitaoka, Takayoshi Wakagi, Hirofumi Shoun, Shinya Fushinobu

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Galacto-N-biose/lacto-N-biose I phosphorylase (GLNBP) from Bifidobacterium longum, a key enzyme for intestinal growth, phosphorolyses galacto-N-biose and lacto-N-biose I with anomeric inversion. GLNBP homologues are often found in human pathogenic and commensal bacteria, and their substrate specificities potentially define the nutritional acquisition ability of these microbes in their habitat. We report the crystal structures of GLNBP in five different ligand-binding forms. This is the first three-dimensional structure of glycoside hydrolase (GH) family 112. The GlcNAc- and GalNAc-bound forms provide structural insights into distinct substrate preferences of GLNBP and its homologues from pathogens. The catalytic domain consists of a partially broken TIM barrel fold that is structurally similar to a thermophilic β-galactosidase, strongly supporting the current classification of GLNBP homologues as one of the GH families. Anion binding induces a large conformational change by rotating a half-unit of the barrel. This is an unusual example of molecular adaptation of a TIM barrel scaffold to substrates.

Original languageEnglish
Pages (from-to)7273-7283
Number of pages11
JournalJournal of Biological Chemistry
Volume284
Issue number11
DOIs
Publication statusPublished - 2009 Mar 13
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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