Comparison of Proteins Secreted into Extracellular Space of Pathogenic and Non-pathogenic Acanthamoeba castellanii

Abstract

Pathogenic Acanthamoeba spp. cause granulomatous amoebic encephalitis and keratitis. Acanthamoeba keratitis (AK) is a rare but serious ocular infection that can result in permanent visual impairment or blindness. However, pathogenic factors of AK remain unclear and treatment for AK is arduous. Expression levels of proteins secreted into extracellular space were compared between A. castellanii pathogenic (ACP) and non-pathogenic strains. Two-dimensional polyacrylamide gel electrophoresis revealed 123 differentially expressed proteins, including 34 increased proteins , 7 qualitative increased proteins, 65 decreased proteins, and 17 qualitative decreased proteins in ACP strain. Twenty protein spots with greater than 5-fold increase in ACP strain were analyzed by liquid chromatography triple quadrupole mass spectrometry. These proteins showed similarity each to inosine-uridine preferring nucleoside hydrolase, carboxylesterase, oxygen-dependent choline dehydrogenase, periplasmic-binding protein proteinases and hypothetical proteins. These proteins expressed higher in ACP may provide some information to understand pathogenicity of Acanthamoeba.

Keywords: Acanthamoeba castellanii; secretory product.

Fig. 1

Two-dimensional gel electrophoresis of up-regulated proteins in A. castellanii. Comparison of ES proteins between ACNP strain (A, C) and ACP strain (B, D) revealed 34 proteins with increased expression (B) and 7 proteins demonstrating qualitative increase (D) in the ACP strain. Numbers in Fig. 1 represents spot identification numbers listed in Supplementary Tables S1 and S2.

Fig. 2

Two-dimensional gel electrophoresis of down-regulated proteins in A. castellanii. Comparision of ES proteins between ACNP strain (A, C) and ACP strain (B, D) showed 65 decreased proteins (B) and 17 qualitatively decreased proteins (D) in the ACP strain. Numbers in Fig. 2 represents spot identification numbers listed in Supplementary Tables S3 and S4.