Locusta migratoria apolipophorin III (apoLp-III) is an exchangeable apolipoprotein found in insect hemolymph. Its role in lipid binding has been extensively studied, but more recently it has been suggested to play a role in the protection against invading pathogens. In the present study, the potential antimicrobial activity of L. migratoria apoLp-III was investigated. The protein was able to bind lipopolysaccharide and demonstrated a strong preference for phosphatidylglycerol vesicles over phosphatidylcholine. To examine the importance of electrostatic forces in the binding interaction with lipopolysaccharide and phosphatidylglycerol membranes the cationic lysine residues in apoLp-III were acetylated. Electrophoresis studies, circular dichroism and fluorescence spectroscopy showed that the acetylated protein retained the ability to bind lipopolysaccharide but was unable to bind phosphatidylglycerol vesicles. These results suggest that L. migratoria apoLp-III has the potential to function as an antimicrobial protein. Additionally, it demonstrates that electrostatic interactions are of major importance in the interaction with phosphatidylglycerol membranes but do not dictate lipopolysaccharide binding.
|Advisor:||Weers, Paul M.|
|Commitee:||Narayanaswami, Vasanthy, Schwans, Jason|
|School:||California State University, Long Beach|
|Department:||Chemistry and Biochemistry|
|School Location:||United States -- California|
|Source:||MAI 55/01M(E), Masters Abstracts International|
|Keywords:||Antimicrobial, Apolipophorin iii, Apolipoproteins, Locusta migratoria|
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