Modulation of the transglycosylation activity of plant family GH18 chitinase by removing or introducing a tryptophan side chain

Naoyuki Umemoto, Takayuki Ohnuma, Takuo Osawa, Tomoyuki Numata, Tamo Fukamizo

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14 Citations (Scopus)

Abstract

Abstract Transglycosylation (TG) activity of a family GH18 chitinase from the cycad, Cycas revoluta, (CrChiA) was modulated by removing or introducing a tryptophan side chain. The removal from subsite +3 through mutation of Trp168 to alanine suppressed TG activity, while introduction into subsite +1 through mutation of Gly77 to tryptophan (CrChiA-G77W) enhanced TG activity. The crystal structures of an inactive double mutant of CrChiA (CrChiA-G77W/E119Q) with one or two N-acetylglucosamine residues occupying subsites +1 or +1/+2, respectively, revealed that the Trp77 side chain was oriented toward +1 GlcNAc to be stacked with it face-to-face, but rotated away from subsite +1 in the absence of GlcNAc at the subsite. Aromatic residues in the aglycon-binding site are key determinants of TG activity of GH18 chitinases.

Original languageEnglish
Article number37276
Pages (from-to)2327-2333
Number of pages7
JournalFEBS Letters
Volume589
Issue number18
DOIs
Publication statusPublished - Aug 12 2015
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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