Substrate binding of a GH5 endoglucanase from the ruminal fungus Piromyces rhizinflata

Chih Wen Tseng, Tzu Ping Ko, Rey Ting Guo, Jian Wen Huang, Hao Ching Wang, Chun Hsiang Huang, Ya Shan Cheng, Andrew H J Wang, Je Ruei Liu

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21 引文 斯高帕斯(Scopus)


The endoglucanase EglA from Piromyces rhizinflata found in cattle stomach belongs to the GH5 family of glycoside hydrolases. The crystal structure of the catalytic domain of EglA shows the (β/α)8-barrel fold typical of GH5 enzymes. Adjacent to the active site of EglA, a loop containing a disulfide bond not found in other similar structures may participate in substrate binding. Because the active site was blocked by the N-terminal His tag of a neighbouring protein molecule in the crystal, enzyme-substrate complexes could not be obtained by soaking but were prepared by cocrystallization. The E154A mutant structure with a cellotriose bound to the -3, -2 and -1 subsites shows an extensive hydrogen-bonding network between the enzyme and the substrate, along with a stacking interaction between Trp44 and the -3 sugar. A possible dimer was observed in the crystal structure, but retention of activity in the E242A mutant suggested that the enzyme probably does not function as a dimer in solution. On the other hand, the first 100 amino acids encoded by the original cDNA fragment are very similar to those in the last third of the (β/α)8-barrel fold, indicating that EglA comprises at least two catalytic domains acting in tandem.
頁(從 - 到)1189-1194
期刊Acta Crystallographica Section F: Structural Biology and Crystallization Communications
出版狀態已發佈 - 十月 2011

ASJC Scopus subject areas

  • 生物化學
  • 生物物理學
  • 結構生物學
  • 遺傳學
  • 凝聚態物理學


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