Studies on structure and function of bacterial yellow affinity substance capable of enhancing enzymatic degradation of cellulose and its gene

平成21~23年度科学研究費補助金(基盤研究（B）)研究成果報告書Clostridium thermocellum ATCC27405株の菌体よりアセトンで抽出した黄色色素を微結晶性セルロース(フナセル)に吸着させ、各種セルラーゼに対する感受性を調べた。その結果、同菌株由来のセルロソームに対しては、未処理のフナセルに比べて約3倍の分解性を示した。また、3種類のセルラーゼとキメラ骨格タンパク質からなるミニセルロソームに対しても約2.5倍の分解性を示した。黄色色素がセルラーゼの分解力を高めることを示した初めての研究例で、今回の発見は極めて重要である。Yellow affinity substance(YAS) extracted from cells of Clostridium thermocellum strain ATCC 27405 using acetone as the extracting solvent was adsorbed to microcrystalline cellulose(Funacel) and its digestibility was examined using some cellulase preparations. YAS-adsorbed Funacel was about 3-folds more efficiently degraded by cellulosome prepared from the culture supernatant of C. thermocellum ATCC 27405 than non-treated Funacel was. In addition, YAS-adsorbed Funacel was 2.5-folds more susceptible to mini-cellulosome constructed from three cellulases and a chimeric scaffolding protein than non-treated Funacel. This is the first study showing that YAS has an ability to enhance susceptibility of cellulose to cellulolytic enzymes