Poster Presentation The 45th Lorne Conference on Protein Structure and Function 2020

A Novel Chemokine-Binding Tick Evasin: EVA-AMA-01 (#143)

Shankar Raj Devkota 1 , Pramod Aryal 1 , Ram Prasad Bhusal 1 , Martin J. Stone 1
  1. Infection and Immunity Program, Monash Biomedicine Discovery Institute, and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia

Inflammation is a normal response of our body to any injury or infection. However, sustained inflammation can cause numerous diseases. The major hallmark of inflammation is leukocyte recruitment to the affected tissue, which is regulated by small secretory proteins called chemokines. They bind and activate chemokine receptors expressed on the leukocyte surface (1). Ticks are hematophagous arachnids that feed on the mammalian host for 2-3 weeks. As a strategy to suppress detection and thereby prolonging their feeding and residence time, ticks produce chemokine-binding proteins called ‘Evasins’, which bind to host chemokines and hence, blocking activation of chemokine receptors and preventing leukocyte migration. A number of studies have shown that Evasins are natural, selective chemokine-inhibitory proteins with excellent potential as therapeutics for inflammatory diseases (2). Using bioinformatics (sequence similarity searches using previously reported Evasin-1 and 4), our research group has identified numerous putative Evasin candidates (3). Notably, we identified variants of previously characterised Evasins from various tick species that have ten cysteine residues forming five disulfide bonds. Herein, we selected EVA-AMA-01 from Ambloymma Maculatum that has conserved ten cysteines residues.  We expressed EVA-AMA-01 using both E. coli and mammalian (HEK cell) expression system. We validated chemokine-neutralising activity of EVA-AMA-01 by using various biochemical and biophysical methods.

  1. Bhusal RP, Foster SR, Stone MJ. Structural basis of chemokine and receptor interactions: Key regulators of leukocyte recruitment in inflammatory responses. Protein Sci 2019.
  2. Bhusal RP, Eaton JRO, Chowdhury ST, Power CA, Proudfoot AEI, Stone MJ, et al. Evasins: Tick Salivary Proteins that Inhibit Mammalian Chemokines. Trends Biochem Sci 2019.
  3. Hayward J, Sanchez J, Perry A, Huang C, Rodriguez Valle M, Canals M, et al. Ticks from diverse genera encode chemokine-inhibitory evasin proteins. J Biol Chem. 2017;292(38):15670-80.