An expansin-like protein from Hahella chejuensis binds cellulose and enhances cellulase activity.

Hee Jin Lee, Saeyoung Lee, Hyeok Jin Ko, Kyoung Heon Kim, In Geol Choi

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

Molecular function of the expansin superfamily has been highlighted for cellulosic biomass conversion. In this report, we identified a new bacterial expansin subfamily by analysis of related bacterial sequences and biochemically examined a member of this new subfamily from Hahella chejuensis (HcEXLX2). Among the various complex polysaccharides tested, HcEXLX2 bound most efficiently to cellulose. The relative binding constant (K( r )) against Avicel was 2.1 L g(-1) at pH 6.0 and 4 degrees C. HcEXLX2 enhanced the activity of cellulase, producing about 4.6 times more hydrolysis product after a 36 h reaction relative to when only cellulase was used. The extension strength test on filter paper indicated that HcEXLX2 has a texture loosening effect on filter paper, which was 53% of that observed for 8 M urea treatment. These activities, compared with a cellulose binding domain from Clostridium thermocellum, implied that the synergistic effect of HcEXLX2 comes from not only binding to cellulose but also disrupting the hydrogen bonds in cellulose. Based on these results, we suggest that the new bacterial expansin subfamily functions by binding to cell wall polysaccharides and increasing the accessibility of cell wall degrading enzymes.

Original languageEnglish
Pages (from-to)379-385
Number of pages7
JournalMolecules and cells
Volume29
Issue number4
DOIs
Publication statusPublished - 2010 Apr

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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