A putative RNA binding protein from Plasmodium vivax apicoplast

Sofía M García‐Mauriño,Christian Grüttner,Antonio Díaz‐Quintana,Francisco Rivero‐Rodríguez,Isabel Cruz‐Gallardo,Irene Díaz‐Moreno,Marian Hernández‐Vellisca

doi:10.1002/2211-5463.12351

Abstract

Malaria is caused by Apicomplexa protozoans from the Plasmodium genus entering the bloodstream of humans and animals through the bite of the female mosquitoes. The annotation of the Plasmodium vivax genome revealed a putative RNA binding protein (apiRBP) that was predicted to be trafficked into the apicoplast, a plastid organelle unique to Apicomplexa protozoans. Although a 3D structural model of the apiRBP corresponds to a noncanonical RNA recognition motif with an additional C‐terminal α‐helix (α3), preliminary protein production trials were nevertheless unsuccessful. Theoretical solvation analysis of the apiRBP model highlighted an exposed hydrophobic region clustering α3. Hence, we used a C‐terminal GFP‐fused chimera to stabilize the highly insoluble apiRBP and determined its ability to bind U‐rich stretches of RNA. The affinity of apiRBP toward such RNAs is highly dependent on ionic strength, suggesting that the apiRBP–RNA complex is driven by electrostatic interactions. Altogether, apiRBP represents an attractive tool for apicoplast transcriptional studies and for antimalarial drug design.

Highlights

Malaria is caused by Apicomplexa protozoans from the Plasmodium genus entering the bloodstream of humans and animals through the bite of the female mosquitoes
The plastid transit peptide (TP) of a putative RNA binding protein (apiRBP) has not been bounded yet, probably due to the fact that they are normally variable in length, have no primary consensus sequence, and are only distinguished by positively charged residues and an abundance of hydroxylated residues [29]
The InterPro Domain search revealed that apiRBP contains a single RNA recognition motif (RRM) of about 90 amino acids whose secondary structure analysis by JPred V.4 [30] corresponded to the canonical b1a1b2b3a2b4 topology, with four-stranded b-sheets packed against two a-helices

Summary

Introduction

Malaria is caused by Apicomplexa protozoans from the Plasmodium genus entering the bloodstream of humans and animals through the bite of the female mosquitoes. The annotation of the Plasmodium vivax genome revealed a putative RNA binding protein (apiRBP) that was predicted to be trafficked into the apicoplast, a plastid organelle unique to Apicomplexa protozoans. Malaria is one of the most devastating parasitic diseases in the world, causing death to 1–2 million people per year, mostly children This disease is caused by Apicomplexa protozoans from the Plasmodium genus passing onto humans and animals through the bite of the female mosquitoes from the Anopheles genus [1]. The discovery of an essential plastid organelle, the so-called apicoplast, has rekindled current search for new drugs to fight malaria [2].

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Conclusion