Objective: The role of Quroum Sensing response regulator nprR on the expression of Cry protein in B. thuringiensis HD-73 was studied.
Methods: The nprR gene deletion mutant HD73 (delta nprR) was constructed by using of homologous recombination. Beta-galactosidase assay of cry1Ac'-lacZ gene fusion and SDS-PAGE in both HD-73 and HD73 (delta nprR) strains were performed to analyze the effect of nprR gene deletion on expression of cry1lAc gene.
Results: Beta-galactosidase assay of nprR'-lacZ in both LB and Schaeffer' s sporulation medium showed nprR gene in B. thuringiensis was initially transcripted at TO (end of Logarithmic growth phase) and keeping expression in stationary phase. Beta-galactosidase assay of cry1Ac'-lacZ and SDS-PAGE indicated that expression of cry1Ac gene in HD73 (delta nprR) was stronger than that in HD-73 during transition phase and early stationary phase. However, Cry expressed product between HD-73 and HD73 (delta nprR) in LB medium has no significant difference when crystal and spore were released.
Conclusion: The deletion of nprR increased expression and transcription activity of cry1Ac during transition and early stationary phase in rich media.