Inhibition of carboxypeptidase b1 from Anopheles stephensi by the potato carboxypeptidase inhibitor: a foundational step toward paratransgenesis-based malaria control

Vector-borne diseases such as malaria are a threat to global public health and the economy. These diseases were proposed to be managed and controlled by new preventive strategies such as paratransgenesis. This is an innovative technique that makes use of symbiotic microorganisms to influence vector or targeted pathogens. The performed studies on Anopheles stephensi and Anopheles gambiae demonstrated that the carboxypeptidase-B1 enzyme plays a vital role in the sexual development of the Plasmodium parasite in the mosquito midgut by its enzymatic activity. Therefore, inhibiting its enzymatic activity could be a target for preventing approaches. Potato Carboxypeptidase Inhibitor (PCI) has desirable characteristics that make it a promising effector molecule for paratransgenesis. In this study, the inhibitory effect of PCI on Carboxypeptidase-1 from An. stephensi (CPBAs1) was evaluated. The coding sequence of the cpbas1 and pci genes were cloned into the pET-23a expression vector, expressed, and purified. Finally, the inhibitory effect of the PCI on CPBAs1 was evaluated in parallel with the 1,10-phenanthroline as the commercial-specific inhibitor. Our findings revealed that PCI could inhibit the enzymatic activity of the CPBAs1 efficiently in low concentrations. Given PCI's remarkable inhibition activity against the CPBAs1 and its suitable structural features, PCI could be considered as a potential effector molecule for use in the paratransgenesis approach in future related studies.