Evidence for substrate binding of a recombinant thermostable xylanase originating fromRhodothermus marinus

The xynl encoded 5 domain xylanase from the thermophilic bacterium Rhodothermus marinus binds specifically to xylan, beta-glucan and amorphous but not crystalline cellulose. Our results show that the binding is mediated by the full length xylanase, but not by the catalytic domain only. Based on similarities concerning both predicted secondary structure and binding specificity found with one cellulose binding domain of CenC from Cellulomonas fimi, we suggest that the binding is mediated by the two N-terminally repeated domains.