Degradation of cellulose substrates by cellulosome chimeras. Substrate targeting versus proximity of enzyme components.

摘要: A library of 75 different chimeric cellulosomes was constructed as an extension our previously described approach for the production model functional complexes (Fierobe, H.-P., Mechaly, A., Tardif, C., Belaich, Lamed, R., Shoham, Y., J.-P., and Bayer, E. A. (2001)J. Biol. Chem. 276, 21257–21261), based on high affinity species-specific cohesin-dockerin interaction. Each complex contained three protein components: (i) a scaffoldin possessing optional cellulose-binding module two cohesins divergent specificity, (ii) cellulases, each bearing dockerin complementary to one cohesins. The activities resultant ternary were assayed using types cellulose substrates. Organization cellulolytic enzymes into cellulosome chimeras resulted in characteristically recalcitrant substrates, whereas showed little or no advantage over free enzyme systems tractable On cellulose, presence domain proximity contributed almost equally their elevated action substrate. For certain pairs, however, effect appeared predominate other. results also indicate that substrate recalcitrance is not necessarily function its crystallinity but reflects overall accessibility reactive sites.