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The β-1,3-Exoglucanase Gene exgA ( exg1 ) of Aspergillus oryzae Is Required to Catabolize Extracellular Glucan, and Is Induced in Growth on a Solid Surface

2007; Oxford University Press; Volume: 71; Issue: 4 Linguagem: Inglês

10.1271/bbb.60591

1347-6947

Koichi Tamano, Yuki Satoh, Tomoko Ishii, Yasunobu Terabayashi, Shinsaku Ohtaki, Motoaki Sano, Tadashi Takahashi, Yasuji Koyama, Osamu Mizutani, Keietsu Abe, Masayuki Machida,

Enzyme Production and Characterization

The biological role of ExgA (Exg1), a secretory β-1,3-exoglucanase of Aspergillus oryzae, and the expression pattern of the exgA (exg1) gene were analyzed. The exgA disruptant and the exgA-overexpressing mutant were constructed, and phenotypes of both mutants were compared. Higher mycelial growth rate and conidiation efficiency were observed for the exgA-overexpressing mutant than for the exgA disruptant when β-1,3-glucan was supplied as sole carbon source. On the other hand, no difference in phenotype was observed between them in the presence or absence of the inhibitors of cell wall β-glucan remodeling when grown with glucose. exgA Expression was induced in growth on solid surfaces such as filter membrane and onion inner skin. A combination of poor nutrition and mycelial attachment to a hydrophobic solid surface appears to be an inducing factor for exgA expression. These data suggest that ExgA plays a role in β-glucan utilization, but is not much involved in cell wall β-glucan remodeling.