Surface proteins, ERAD and antigenic variation in Trypanosoma brucei
File(s)nihms868246.pdf (1.26 MB)
Accepted version
Author(s)
Tiengwe, Calvin
Muratore, Katherine A
Bangs, James D
Type
Journal Article
Abstract
Variant surface glycoprotein (VSG) is central to antigenic variation in African trypanosomes. Although much prior work documents that VSG is efficiently synthesized and exported to the cell surface, it was recently claimed that 2–3 fold more is synthesized than required, the excess being eliminated by ER‐Associated Degradation (ERAD) (Field et al., 2010). We now reinvestigate VSG turnover and find no evidence for rapid degradation, consistent with a model whereby VSG synthesis is precisely regulated to match requirements for a functional surface coat on each daughter cell. However, using a mutated version of the ESAG7 subunit of the transferrin receptor (E7:Ty) we confirm functional ERAD in trypanosomes. E7:Ty fails to assemble into transferrin receptors and accumulates in the ER, consistent with retention of misfolded protein, and its turnover is selectively rescued by the proteasomal inhibitor MG132. We also show that ER accumulation of E7:Ty does not induce an unfolded protein response. These data, along with the presence of ERAD orthologues in the Trypanosoma brucei genome, confirm ERAD in trypanosomes. We discuss scenarios in which ERAD could be critical to bloodstream parasites, and how these may have contributed to the evolution of antigenic variation in trypanosomes.
Date Issued
2016-07-01
Date Acceptance
2016-04-12
Citation
Cellular Microbiology, 2016, 18 (11), pp.1673-1688
ISSN
1462-5814
Publisher
Wiley
Start Page
1673
End Page
1688
Journal / Book Title
Cellular Microbiology
Volume
18
Issue
11
Copyright Statement
© 2016 John Wiley & Sons Ltd. This is the accepted version of the article, which has been published in final form at https://doi.org/10.1111/cmi.12605
Subjects
0605 Microbiology
1108 Medical Microbiology
Microbiology
Publication Status
Published
Date Publish Online
2016-07-01