Heterologous Expression and Functional Characterization of CAP18 from .

BACKGROUND

Antimicrobial peptides belong to the innate defence system of creatures. These peptides attach to the bacterial membrane in order to die microorganisms by penetrating them. Hence, biotechnology researchers pay more attention to produce antimicrobial peptides for use in various fields. The studies showed that rabbit tissue with inflammation and skin ulcers would be producing CAP18 peptide, which belongs to the cathelicidin group.

METHODS

In this study, the optimized sequence of the cap18 gene was placed into the pPICZAα plasmid after the alpha-factor signal and transformed into (X-33 strain). Purification of the recombinant peptide was done based on its histidine tail at C-terminal, and western blotting method was used to demonstrate the purification of rCAP18. The antibacterial activity of the purified and desalted rCAP18 was investigated at different concentrations against pathogenic bacteria.

RESULTS

The maximum expression level of rCAP18 (17.5 kDa) was seen 90 h after induction of alcohol oxidase I (AOX1) promoter with methanol. The concentration of rCAP18 was 33 mg/L after purification with Ni-NTA Sepharose column. The function of rCAP18 (4.3, 5.7, 7 µg/ml) was investigated against and . Results showed that %CFU/cm reached 28% after cells treatment with 7 μg/ml of rCAP18.

CONCLUSION

This study presented the findings related to heterologous expression of gene, and evaluation of rCAP18 antibacterial effects. Our results showed that rCAP18 plays a significant role in inhibiting bacterial growth, especially Gram-negative bacteria.