Effects of domains modification on the catalytic potential of chitinase from Pseudomonas aeruginosa

Chitinase, an important enzyme in chitin-degrading, have extensive biophysiological functions and immense potential applications. Here, a chitinase gene pachi was cloned from Pseudomonas aeruginosa and overexpressed in E. coli (DE3). The structural analysis showed that chitinase pachi consists of catalytic domain (CHC), chitin binding domain (CBD) and both of these are linked by connective domain (FN3). In this study, Pachi displayed optimal activity at temperature 65 °C and pH 6.5. To understand the structural and functional relationship of chitin-binding domain with catalytic domain, two mutants, CHA (without CBD) and CBD + FN3-pachi with additional CBD have been constructed. Though the results showed that the two mutants have similar characteristics with Pachi, it is interesting to note that the deficiency of CBD caused an increase in expression level as well as solubility of the CHA. Moreover, the catalytic efficiency of CHA was increased 1.26-fold and substrate affinity in the absence of CBD was decreased 1.85-fold. Thus, the improved solubility and activity of CHA by domain deficiency is an interesting pathway to study the relationship of structure and function of chitinase and support its potential use in commercial applications.