Research

Numerous atypical proteins at the surface of amoebas

Molecules that are located at the surface of pathogens are of particular interest for the infection process. In pathogenic amoebas (Entamoeba histolytica), they influence the migration from the intestinal cavity into the tissues and the development of intestinal ulcers and organ abscesses.

Immunofluorescence microscopy to show surface localisation of several amoeba proteins (Entamoeba histolytica). The nucleus of the amoeba is stained in blue, proteins as indicated in green.
Immunofluorescence microscopy to show surface localisation of several amoeba proteins (Entamoeba histolytica). The nucleus of the amoeba is stained in blue, proteins as indicated in green. In the centre, an enlarged amoeba with all the surface proteins studied labelled.

Therefore, we have studied the „surface proteome“ of E. histolytica, i.e. the entirety of proteins the amoebas carry on their surface. We have labelled live amoebas with a substance that spontaneously binds to all accessible proteins, isolated the labelled proteins and subjected them to mass spectrometry. Bioinformatic analysis of the protein fragments revealed in about half of the nearly 700 proteins, no evidence of structures that commonly anchor proteins to a cell surface. We selected 23 of them at random, labelled these with a fluorescent marker and found that 20 of them indeed fluoresce at the amoeba surface. Apparently, the rapid turnover of the amoeba cell membrane temporarily flushes many intracellular proteins onto the surface.

 


Biller L et al. Mol Cell Prot., 2014, 13, 132-44.

Laura Biller, Jenny Matthiesen, Vera Kühne, Hannelore Lotter, Ghassan Handal, Egbert Tannich, Iris Bruchhaus and external co-operation partners (see publication)