Polysaccharide-Inducible Endoglucanases from Lentinula edodes Exhibit a Preferential Hydrolysis of 1,3-1/4-β-Glucan and Xyloglucan

摘要

Three genes encoding glycoside hydrolase family 12 (GH12) enzymes from Lentinula edodes, namely Lecel12A, Lecel12B, and Lecel12C, were newly cloned by PCR using highly conserved sequence primers. To investigate enzymatic properties, recombinant enzymes encoded by L. edodes DNAs and GH12 genes from Postia placenta (PpCel12A and PpCel12B) and Schizophyllum commune (ScCell2A) were prepared in Brevibacillus choshinensis. Recombinant LeCel12A, PpCell2A, and PpCell2B, which were grouped in GH12 subfamily 1, preferentially hydrolyzed 1,3-1,4-β-glucan. By contrast, LeCell2B, LeCell2C, and ScCell2A, members of the subfamily 2, exhibited specific hydrolysis of xyloglucan. These results suggest that two subfamilies of GH12 are separated based on the substrate specificity. Transcript levels of L. edodes genes increased 72 h after growth of L. edodes mycelia cells in the presence of plant cell wall polymers such as xyloglucan, l,3—l,4-β-gIucan, and cellulose. These results suggest that L. edodes GH12 enzymes have evolved to hydrolyze 1,3—1,4-β-glucan and xyloglucan, which might enhance hyphal extension and nutrient acquisition.