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Biological variation among african trypanosomes: I. Clonal expression of virulence is not linked to the variant surface glycoprotein or the variant surface glycoprotein gene telomeric expression site.

ABSTRACT: The potential association of variant surface glycoprotein (VSG) gene expression with clonal expression of virulence in African trypanosomes was addressed. Two populations of clonally related trypanosomes, which differ dramatically in virulence for the infected host, but display the same apparent VSG surface coat phenotype, were characterized with respect to the VSG genes expressed as well as the chromosome telomeric expression sites (ES) utilized for VSG gene transcription. The VSG gene sequences expressed by clones LouTat 1 and LouTat 1A of Trypanosoma brucei rhodesiense were identical, and gene expression in both clones occurred precisely by the same gene conversion events (duplication and transposition), which generated an expression-linked copy (ELC) of the VSG gene. The ELC was present on the same genomic restriction fragments in both populations and resided in the telomere of a 330-kb chromosome; a single basic copy of the LouTat 1/1A VSG gene, present in all variants of the LouTat 1 serodeme, was located at an internal site of a 1.5-Mb chromosome. Restriction endonuclease mapping of the ES telomere revealed that the VSG ELC of clones LouTat 1 and 1A resides in the same site. Therefore, these findings provide evidence that the VSG gene ES and, potentially, any cotranscribed ES-associated genes do not play a role in the clonal regulation of virulence because trypanosome clones LouTat 1 and 1A, which differ markedly in their virulence properties, both express identical VSG genes from the same chromosome telomeric ES.

SUBMITTER: Inverso JA

PROVIDER: S-EPMC2936953 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Biological variation among african trypanosomes: I. Clonal expression of virulence is not linked to the variant surface glycoprotein or the variant surface glycoprotein gene telomeric expression site.

Inverso Jill A JA Uphoff Timothy S TS Johnson Scott C SC Paulnock Donna M DM Mansfield John M JM

DNA and cell biology 20100501 5

The potential association of variant surface glycoprotein (VSG) gene expression with clonal expression of virulence in African trypanosomes was addressed. Two populations of clonally related trypanosomes, which differ dramatically in virulence for the infected host, but display the same apparent VSG surface coat phenotype, were characterized with respect to the VSG genes expressed as well as the chromosome telomeric expression sites (ES) utilized for VSG gene transcription. The VSG gene sequence ...[more]

PMID: 20307190

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Project description:Variant Surface Glycoproteins (VSG) coat parasitic African trypanosomes and underpin antigenic variation and immune evasion. This VSG is a super-abundant virulence factor that is subject to post-transcriptional gene expression controls mediated via the VSG 3’-untranslated region (3’-UTR). To identify positive VSG regulators in bloodstream form cells, we used prior genome-scale screening data to prioritise mRNA binding protein (mRBPs) knockdowns that phenocopy VSG mRNA knockdown, displaying both loss-of-fitness and pre-cytokinesis accumulation. The top three candidate VSG regulators were CFB2 (cyclin F-box protein 2, Tb927.1.4650), MKT1 (Tb927.6.4770) and PBP1 (polyadenylate binding-protein binding-protein, Tb927.8.4540). Notably, CFB2 was recently found to regulate VSG transcript stability, and all three proteins were found to associate with each other. We used data-independent acquisition for accurate label-free quantification and deep proteome coverage to quantify expression profiles following depletion of each mRBP. Only CFB2 knockdown significantly reduced VSG expression and the expression of a reporter under the control of a VSG 3’-untranslated region (3’-UTR). CFB2 knockdown also triggered depletion of cytoplasmic ribosomal proteins, consistent with translation arrest observed when VSG synthesis is blocked. In contrast, PBP1 knockdown triggered depletion of CFB2, MKT1, and other components of the PBP1-complex. Finally, all three knockdowns triggered depletion of cytokinesis initiation factors, consistent with the cytokinesis defect that was confirmed here for all three knockdowns. Thus, genome-scale knockdown datasets facilitate the triage and prioritisation of candidate regulators. Quantitative proteomic analysis confirms 3’-UTR dependent positive control of VSG expression by CFB2 and interactions with additional mRBPs. Our results also reveal connections between VSG expression control by CFB2, ribosomal protein expression, and cytokinesis.

Dataset Information

Biological variation among african trypanosomes: I. Clonal expression of virulence is not linked to the variant surface glycoprotein or the variant surface glycoprotein gene telomeric expression site.

Publications

Biological variation among african trypanosomes: I. Clonal expression of virulence is not linked to the variant surface glycoprotein or the variant surface glycoprotein gene telomeric expression site.

Similar Datasets

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