Abstract:

Discussed in this paper are the heterologous expression of a truncated scaffolding protein from Clostri-dium acetobutylicum containing a cellulose- binding module and two cohesin modules,and a recombinant endoglu-canase E4SD,a family of 9 cellulase Cel9A catalysis domain from Thermomonospora fusca appended with C.aceto-butylicum dockerin in C- terminal,which are both produced by E.coli BL21 (DE3),and subsequently purified,mixed,and then assembled with minicellulosomes by calcium- mediated cohesin- dockerin interaction ex- vivo.Theresults show that the truncated scaffoldin CipA is successfully assembled with recombinant endoglucanase E4SD toform minicellulosome via cohesin- dockerin interaction,and that,as compared with those in enzyme- free state,theenzyme activities of E4SD in carboxymethyl cellulose hydrolysis and microcrystal cellulose hydrolysis respectivelyimprove by 30% and 200%.Thus,it is demonstrated that noncellulosomal cellulase,especially the cellulase withexcellent enzymatic characteristics from other species,can incorporate into C.acetobutylicum cellulosome by ap-pending a C.acetobutylicum dockerin and can synergize with other cellulase to hydrolyze cellulose more efficiently.

Key words: endoglucanase E4, minicellulosome, scaffoldin, dockerin, cohesin