Structural Rearrangements of Sucrose Phosphorylase from Bifidobacterium adolescentis during Sucrose Conversion

O. Mirza, L.K. Skov, D. Sprogoe, L.A.M. van den Broek, G. Beldman, J.S. Kastrup, M. Gajhede

Research output: Contribution to journalArticleAcademicpeer-review

59 Citations (Scopus)

Abstract

The reaction mechanism of sucrose phosphorylase from Bifidobacterium adolescentis (BiSP) was studied by site-directed mutagenesis and x-ray crystallography. An inactive mutant of BiSP (E232Q) was co-crystallized with sucrose. The structure revealed a substrate-binding mode comparable with that seen in other related sucrose-acting enzymes. Wild-type BiSP was also crystallized in the presence of sucrose. In the dimeric structure, a covalent glucosyl intermediate was formed in one molecule of the BiSP dimer, and after hydrolysis of the glucosyl intermediate, a -D-glucose product complex was formed in the other molecule. Although the overall structure of the BiSP-glucosyl intermediate complex is similar to that of the BiSP(E232Q)-sucrose complex, the glucose complex discloses major differences in loop conformations. Two loops (residues 336-344 and 132-137) in the proximity of the active site move up to 16 and 4Å, respectively. On the basis of these findings, we have suggested a reaction cycle that takes into account the large movements in the active-site entrance loops.
Original languageEnglish
Pages (from-to)35576-35584
JournalJournal of Biological Chemistry
Volume281
Issue number46
DOIs
Publication statusPublished - 2006

Keywords

  • alpha-amylase family
  • crystal-structure
  • neisseria-polysaccharea
  • amylosucrase
  • mechanism
  • glucose
  • complex
  • enzyme

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