Characterisation and expression analysis of trophozoite and cyst proteins of Acanthamoeba spp. isolated from Acanthamoeba keratitis (AK) patient

Abstract

The study was carried out to characterise and analyze the expression pattern of proteins of infective trophozoite and cyst forms of Acanthamoeba spp. isolated from an amoebic keratitis patient. Protein was isolated from the trophozoites and cysts of Acanthamoeba spp. isolates and subjected to SDS PAGE, 2D PAGE analysis where a large number of protein bands and protein spots were observed. Four prominent protein spots i.e. 2 from trophozoites and 2 from cysts that appeared more intense compared to the corresponding spots in other corresponding gel were excised from the 2D PAGE gels and analysed by MALDI-TOF/TOF MS assay and Mascot search software. Protein spots from trophozoites were identified as “hypothetical protein ACA1” and “eukaryotic porin protein” and those from cysts were identified as “chaperone protein DnaK” and “chaperonin protein” respectively. Proteomic results of 4 proteins were further validated by reverse genomics using quantitative real time PCR assay which showed a 1388 fold and 4.35 fold increase in expression of “hypothetical protein ACA1” gene and “eukaryotic porin protein” gene respectively in trophozoites compared to cysts and a 15 fold and 12.36 fold increase in expression of “chaperone protein DnaK” gene and “chaperonin protein” gene respectively in cysts compared to trophozoites. “Hypothetical protein ACA1” of trophozoites, whose function is unknown might have some important role in the parasite division and pathogenicty of Acanthamoeba spp. which needs further study. As trophozoites are the active and feeding form of Acanthamoeba spp., “eukaryotic porin” proteins may have some important role in efflux of toxic metabolites and exudates from interior of cell to outside along with some role in pathogenicity. Similarly proteins such as “chaperone protein DnaK” and “chaperonin protein” which belongs to group of heat shock proteins may have a role in folding of cyst specific proteins in cyst which needs further study.