Yeast surface display identifies a family of evasins from ticks with novel polyvalent CC chemokine-binding activities

Kamayani Singh,Shoumo Bhattacharya,Graham Davies,James R O Eaton,Yara Alenazi,Akane Kawamura

doi:10.1038/s41598-017-04378-1

Kamayani Singh, Shoumo Bhattacharya + Show 4 more

Open Access

https://doi.org/10.1038/s41598-017-04378-1

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Abstract

Chemokines function via G-protein coupled receptors in a robust network to recruit immune cells to sites of inflammation. Due to the complexity of this network, targeting single chemokines or receptors has not been successful in inflammatory disease. Dog tick saliva contains polyvalent CC-chemokine binding peptides termed evasins 1 and 4, that efficiently disrupt the chemokine network in models of inflammatory disease. Here we develop yeast surface display as a tool for functionally identifying evasins, and use it to identify 10 novel polyvalent CC-chemokine binding evasin-like peptides from salivary transcriptomes of eight tick species in Rhipicephalus and Amblyomma genera. These evasins have unique binding profiles compared to evasins 1 and 4, targeting CCL2 and CCL13 in addition to other CC-chemokines. Evasin binding leads to neutralisation of chemokine function including that of complex chemokine mixtures, suggesting therapeutic efficacy in inflammatory disease. We propose that yeast surface display is a powerful approach to mine potential therapeutics from inter-species protein interactions that have arisen during evolution of parasitism in ticks.

Highlights

Chemokines function via G-protein coupled receptors in a robust network to recruit immune cells to sites of inflammation
Chemokines function to recruit inflammatory and immune cells, including monocytes, neutrophils, eosinophils, dendritic cells, and T and B lymphocytes, to sites of inflammation and injury[3,4,5]. They bind to a family of G-protein coupled chemokine receptors (GPCRs) on these cells through two chemokine receptor sites (CRS1 and CRS2)
The chemokine globular core binds to the extracellular N-terminus (CRS1) of the receptor via the proximal N-terminus and N-loop/40S loop grooves, whereas the chemokine distal N-terminus binds to CRS2 in the GPCR pocket, and is essential for activating signaling and chemotaxis[6]

Summary

Introduction

Chemokines function via G-protein coupled receptors in a robust network to recruit immune cells to sites of inflammation. We develop yeast surface display as a tool for functionally identifying evasins, and use it to identify 10 novel polyvalent CC-chemokine binding evasin-like peptides from salivary transcriptomes of eight tick species in Rhipicephalus and Amblyomma genera. These evasins have unique binding profiles compared to evasins 1 and 4, targeting CCL2 and CCL13 in addition to other CC-chemokines. Chemokines function to recruit inflammatory and immune cells, including monocytes, neutrophils, eosinophils, dendritic cells, and T and B lymphocytes, to sites of inflammation and injury[3,4,5] They bind to a family of G-protein coupled chemokine receptors (GPCRs) on these cells through two chemokine receptor sites (CRS1 and CRS2). A characteristic of CKBPs is that they target the invariant disulfide in all chemokines[13]

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