Hemelipoglycoprotein from the ornate sheep tick, Dermacentor marginatus: structural and functional characterization

Area of Science:

• Biochemistry
• Tick Biology
• Immunology

Background:

• Tick carrier proteins bind and transport heme, acting as antioxidants.
• The precise roles of these proteins in tick physiology, especially in males and salivary glands, remain unclear.
• Carrier proteins bind limited heme relative to their large size.

Purpose of the Study:

• Biochemically characterize hemelipoglycoprotein from Dermacentor marginatus.
• Determine its native size, glycosylation, and glycan composition.
• Investigate its carbohydrate-binding specificity.

Main Methods:

• Purification of hemelipoglycoprotein via immunoprecipitation and SDS-PAGE.
• Analysis of protein subunits and N-glycans.
• Assessment of red blood cell agglutination and carbohydrate-binding activity.
• Detection of protein in various tick tissues and plasma.

Main Results:

• A 290 kDa hemelipoglycoprotein with two subunits (95 and 100 kDa) was purified.
• The protein is glycosylated with high-mannose and complex N-glycans.
• It exhibits galactose- and mannose-binding specificity and agglutinates red blood cells.
• Hemelipoglycoprotein forms complexes with other proteins in tick plasma and is found in hemocytes, salivary glands, and gut.

Conclusions:

• The characterized hemelipoglycoprotein from Dermacentor marginatus is a complex, glycosylated protein.
• Its carbohydrate-binding activity and association with other proteins suggest a role in tick innate immunity.
• Both glycosylated and deglycosylated forms are present in salivary glands.