Comparative Analysis of Apicoplast-Targeted Protein Extension Lengths in Apicomplexan Parasites

Abstract

In general, the mechanism of protein translocation through the apicoplast membrane requires a specific extension of a functionally important region of the apicoplast-targeted proteins. The corresponding signal peptides were detected in many apicomplexans but not in the majority of apicoplast-targeted proteins inToxoplasma gondii. InT. gondiisignal peptides are either much diverged or their extension region is processed, which in either case makes the situation different from other studied apicomplexans. We propose a statistic method to compare extensions of the functionally important regions of apicoplast-targeted proteins. More specifically, we provide a comparison of extension lengths of orthologous apicoplast-targeted proteins in apicomplexan parasites. We focus on results obtained for the model speciesT. gondii,Neospora caninum, andPlasmodium falciparum. With our method, cross species comparisons demonstrate that, in average, apicoplast-targeted protein extensions inT. gondiiare 1.5-fold longer than inN. caninumand 2-fold longer than inP. falciparum. Extensions inP. falciparumless than 87 residues in size are longer than the corresponding extensions inN. caninumand, reversely, are shorter if they exceed 88 residues.