Investigating Molecular Assembly and Dynamics of Tick Cement proteins

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Summary Ticks must use their barbed mouthparts (hypostome) to pierce deeply into the host’s dermis (skin), then encase the hypostome in a cement cone in order to maintain a firm, pain and itch- free attachment, subsequently transmitting infectious disease agents into the victim. Two types of cement have been found in ticks; early cement which is secreted only minutes after attachment and hardens rapidly, and late cement which is secreted 24 hours after attachment to the host and hardens gradually. These secreted cement cones are composed of several glycine-rich proteins (GRPs) which are a large family of diverse proteins that are known for their adhesive and tensile characteristics. Such properties may play an important role in host skin attachment to gain an uninterrupted supply of blood over a prolonged period of time. Our long- term plan in the AREA grant application is to reveal the functions and biochemical properties of novel GRPs in cement cone assembly, stealth attachment, hematophagy (blood feeding) and climatic adaptation. We will test our central hypothesis that biochemical and biomechanical properties of GRPs assist in the undetected attachment to the host, providing access to an uninterrupted supply of blood by serving as scaffolding for the cement cone apparatus. Our multidisciplinary team will test the hypothesis using a combination of artificial membrane feeding, structural, proteomics, and reverse genetics approaches. Specific aims are to: 1) determine the role of unique salivary GRPs in cement cone assembly and secure attachment by using an artificial membrane feeding system, and 2) define the biochemical properties of uncharacterized recombinantly expressed cement cone proteins. Targeting tick cement proteins may provide an innovative way to create a hostile situation for tick attachment, and ultimately interrupt the inoculation of tick-borne pathogens into the host. Understanding the mechanisms of cement assembly that allow the tick to secure a stable, stealthy attachment will provide insight into developing new control and prevention methods.