Exploration of Two Pectate Lyases from Caldicellulosiruptor bescii Reveals that the CBM66 Module Has a Crucial Role in Pectic Biomass Degradation

Abstract

Thermophilic proteins could be implemented in diverse industrial applications. We sought to characterize two pectate lyases, Cb PL3 and Cb PL9, from a thermophilic bacterium, Caldicellulosiruptor bescii . The two enzymes share a high optimum temperature, a low optimum pH, and good thermostability at the evaluated temperature. A family 66 carbohydrate-binding module ( Cb CBM66) was identified in the two Cb PLs, sharing 100% amino acid identity. The deletion of Cb CBM66 dramatically decreased the activity of Cb PL9 but increased the activity and thermostability of Cb PL3, suggesting different roles of Cb CBM66 in the two enzymes. Moreover, the degradation products of the two Cb PLs were different. These results revealed that these enzymes could represent potential pectate lyases for applications in the paper and textile industries.