Heterologous expression and characterization of endocellulase from the Japanese pine sawyer Monochamus saltuarius (MsGHF5)

In this study, the endocellulase gene from Monochamus saltuarius (MsGHF5) was transformed into Escherichia coli (RosettaBlue(DE3)pLysS strain), and induced by IPTG. The molecular weight of recombinant MsGHF5 (rMsGHF5) was 78 kDa and was expressed as a fusion protein with maltose binding protein in pMAL‐c2 expression vector. Native‐PAGE was conducted with 0.1% carboxymethyl cellulose as a substrate, and the zymogenic bands were observed. The Michaelis constant and maximum velocity of rMsGHF5 were 0.199 mg/mL and 0.034 μmol/min/mL, respectively. The optimal condition for rMsGHF5 occurred at pH 5 and 30°C. Fe²⁺ and Mn²⁺ stimulated the activity of rMsGHF5 by 167 and 114% respectively, whereas Cu²⁺, Hg²⁺ and Zn²⁺ inhibited its activity.