Identification of potential protein partners that bind to the variant surface glycoprotein inTrypanosoma equiperdum

Abstract

Trypanosoma equiperdum possesses a dense coat of a variant surface glycoprotein (VSG) that is used to evade the host immune response by a process known as antigenic variation. Soluble and membrane forms of the predominant VSG from the Venezuelan T. equiperdum TeAp-N/D1 strain (sVSG and mVSG, respectively) were purified to homogeneity; and antibodies against sVSG and mVSG were raised, isolated, and employed to produce anti-idiotypic antibodies that structurally mimic the VSG surface. Prospective VSG-binding partners were initially detected by far-Western blots, and then by immunoblots using the generated anti-idiotypic antibodies. Polypeptides of ~80 and 55 kDa were isolated when anti-idiotypic antibodies-Sepharose affinity matrixes were used as baits. Mass spectrometry sequencing yielded hits with various proteins from Trypanosoma brucei such as heat-shock protein 70, tryparedoxin peroxidase, VSG variants, expression site associated gene product 6, and two hypothetical proteins. In addition, a possible interaction with a protein homologous to the glutamic acid/alanine-rich protein from Trypanosoma congolense was also found. These results indicate that the corresponding orthologous gene products are candidates for VSG-interacting proteins in T. equiperdum.

The Glycosylphosphatidylinositol Anchor: A Linchpin for Cell Surface Versatility of Trypanosomatids

“…A common, and specific, characteristic of the African trypanosomes is the VSG coat that covers the cell surface of their bloodstream forms ( Uzcanga et al, 2004 ; Jackson et al, 2013 , 2015 ; Carnes et al, 2015 ; Carrasquel et al, 2017 ). Due to the close relationship between T. brucei , T. evansi , and T. equiperdum , a high degree of similarity in their surface molecules is not unexpected.…”