Biochemical characterization of AeD7L2 and its physiological relevance in blood feeding in the dengue mosquito vector, Aedes aegypti

• Published in: The FEBS journal Vol. 288; no. 6; pp. 2014 - 2029
• Main Authors: Martin‐Martin, Ines, Kern, Olivia, Brooks, Steven, Smith, Leticia Barion, Valenzuela‐Leon, Paola Carolina, Bonilla, Brian, Ackerman, Hans, Calvo, Eric
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.03.2021
• Subjects: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid - metabolism; Aedes - metabolism; Aedes - physiology; Aedes - virology; Aedes aegypti; Affinity; Agglomeration; Amines; Amino Acid Sequence; Animals; arthropods; Binding; Biogenic amines; Blood coagulation; Blood Coagulation - physiology; Blood platelets; Blood pressure; Coagulation; Collagen; Dengue - metabolism; Dengue - virology; Dengue fever; Dengue Virus - physiology; Eicosanoids; Feeding Behavior - physiology; Gene Expression; Hemostasis; Hemostatics; Insect Proteins - chemistry; Insect Proteins - genetics; Insect Proteins - metabolism; Models, Molecular; Mosquito Vectors - metabolism; Mosquito Vectors - virology; Mosquitoes; Norepinephrine; Physiology; Platelet aggregation; Platelet Aggregation - physiology; Protein Binding; Protein Conformation; Proteins; Saliva; salivary glands; Salivary Proteins and Peptides - chemistry; Salivary Proteins and Peptides - genetics; Salivary Proteins and Peptides - metabolism; Sequence Homology, Amino Acid; Thromboxane A2; vascular biology; Vasoconstriction; vasodilators; Vector-borne diseases; salivary glands; vascular biology; vasodilators; arthropods; platelet aggregation
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/febs.15524

When a mosquito inserts its mouth parts into the host skin, it causes tissue and vascular damage that triggers host hemostatic responses. Mosquito saliva is injected at the bite site to counteract the hemostasis and help blood‐feeding. D7 salivary proteins bind and scavenge several hemostasis agonists such as serotonin, norepinephrine, and U‐46619. Therefore, D7 proteins inhibit the action of the host molecules and prevent vasoconstriction and platelet aggregation. Aedes aegypti saliva facilitates blood meal acquisition through pharmacologically active compounds that prevent host hemostasis. Among these salivary proteins are the D7s, which are highly abundant and have been shown to act as scavengers of biogenic amines and eicosanoids. In this work, we performed comparative structural modeling, characterized the binding capabilities, and assessed the physiological functions of the Ae. aegypti salivary protein AeD7L2 compared to the well‐characterized AeD7L1. AeD7L1 and AeD7L2 show different binding affinities to several biogenic amines and biolipids involved in host hemostasis. Interestingly, AeD7L2 tightly binds U‐46619, the stable analog of thromboxane A2 (KD = 69.4 nm), which is an important platelet aggregation mediator, while AeD7L1 shows no binding. We tested the ability of these proteins to interfere with the three branches of hemostasis: vasoconstriction, platelet aggregation, and blood coagulation. Pressure myography experiments showed these two proteins reversed isolated resistance artery vasoconstriction induced by either norepinephrine or U‐46619. These proteins also inhibited platelet aggregation induced by low doses of collagen or U‐46619. However, D7 long proteins did not affect blood coagulation. The different ligand specificity and affinities of AeD7L1 and AeD7L2 matched our experimental observations from studying their effects on vasoconstriction and platelet aggregation, which confirm their role in preventing host hemostasis. This work highlights the complex yet highly specific biological activities of mosquito salivary proteins and serves as another example of the sophisticated biology underlying arthropod blood feeding.