scholarly journals Trypanosoma brucei: enrichment by UV of intergenic transcripts from the variable surface glycoprotein gene expression site.

1989 ◽  
Vol 9 (9) ◽  
pp. 4022-4025 ◽  
Author(s):  
H Coquelet ◽  
P Tebabi ◽  
A Pays ◽  
M Steinert ◽  
E Pays
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Uv Irradiation ◽  
Surface Glycoprotein ◽  
Putative Promoter Region ◽  
Variable Surface Glycoprotein ◽  
Polycistronic Transcription ◽  
Variable Surface ◽  
Intergenic Regions ◽  
Expression Site

The expression site for the variable surface glycoprotein (VSG) gene AnTat 1.3A of Trypanosoma brucei is 45 kilobases long and encompasses seven expression site-associated genes (ESAGs) (E. Pays, P. Tebabi, A. Pays, H. Coquelet, P. Revelard, D. Salmon, and M. Steinert, Cell 57:835-845, 1989). After UV irradiation, several large transcripts from the putative promoter region were strongly enriched. We report that one such major transcript starts near the poly(A) addition site of the first gene (ESAG 7), spans the intergenic region, and extends to the poly(A) addition site of the second gene (ESAG 6), thus bypassing the normal 3' splice site of the ESAG 6 mRNA. Since this transcript is spliced, we conclude that UV irradiation does not inhibit splicing but stabilizes unstable processing products. This demonstrates that at least some intergenic regions of the VSG gene expression site are continuously transcribed in accordance with a polycistronic transcription model.

Trypanosoma brucei: enrichment by UV of intergenic transcripts from the variable surface glycoprotein gene expression site

1989 ◽  
Vol 9 (9) ◽  
pp. 4022-4025
Author(s):  
H Coquelet ◽  
P Tebabi ◽  
A Pays ◽  
M Steinert ◽  
E Pays
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Uv Irradiation ◽  
Surface Glycoprotein ◽  
Putative Promoter Region ◽  
Variable Surface Glycoprotein ◽  
Polycistronic Transcription ◽  
Variable Surface ◽  
Intergenic Regions ◽  
Expression Site

The expression site for the variable surface glycoprotein (VSG) gene AnTat 1.3A of Trypanosoma brucei is 45 kilobases long and encompasses seven expression site-associated genes (ESAGs) (E. Pays, P. Tebabi, A. Pays, H. Coquelet, P. Revelard, D. Salmon, and M. Steinert, Cell 57:835-845, 1989). After UV irradiation, several large transcripts from the putative promoter region were strongly enriched. We report that one such major transcript starts near the poly(A) addition site of the first gene (ESAG 7), spans the intergenic region, and extends to the poly(A) addition site of the second gene (ESAG 6), thus bypassing the normal 3' splice site of the ESAG 6 mRNA. Since this transcript is spliced, we conclude that UV irradiation does not inhibit splicing but stabilizes unstable processing products. This demonstrates that at least some intergenic regions of the VSG gene expression site are continuously transcribed in accordance with a polycistronic transcription model.

Trypanosoma brucei: posttranscriptional control of the variable surface glycoprotein gene expression site

1989 ◽  
Vol 9 (9) ◽  
pp. 4018-4021
Author(s):  
E Pays ◽  
H Coquelet ◽  
A Pays ◽  
P Tebabi ◽  
M Steinert
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Transcription Initiation ◽  
Tsetse Fly ◽  
Surface Glycoprotein ◽  
Insect Vector ◽  
Variable Surface Glycoprotein ◽  
A Genome ◽  
Variable Surface ◽  
Expression Site

The arrest of variable surface glycoprotein (VSG) synthesis is one of the first events accompanying the differentiation of Trypanosoma brucei bloodstream forms into procyclic forms, which are characteristic of the insect vector. This is because of a very fast inhibition of VSG gene transcription which occurs as soon as the temperature is lowered. We report that this effect is probably not controlled at the level of transcription initiation, since the beginning of the VSG gene expression site, about 45 kilobases upstream from the antigen gene, remains transcribed in procyclic forms. The permanent activity of the promoter readily accounts for the systematic reappearance, upon return to the bloodstream form after cyclical transmission, of the antigen type present before passage to the tsetse fly. The abortive transcription of the VSG gene expression site appears linked to RNA processing abnormalities. Such posttranscriptional controls may allow the modulation of gene expression in a genome organized in large multigenic transcription units.

scholarly journals Trypanosoma brucei: posttranscriptional control of the variable surface glycoprotein gene expression site.

1989 ◽  
Vol 9 (9) ◽  
pp. 4018-4021 ◽  
Author(s):  
E Pays ◽  
H Coquelet ◽  
A Pays ◽  
P Tebabi ◽  
M Steinert
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Transcription Initiation ◽  
Tsetse Fly ◽  
Surface Glycoprotein ◽  
Insect Vector ◽  
Variable Surface Glycoprotein ◽  
A Genome ◽  
Variable Surface ◽  
Expression Site

The arrest of variable surface glycoprotein (VSG) synthesis is one of the first events accompanying the differentiation of Trypanosoma brucei bloodstream forms into procyclic forms, which are characteristic of the insect vector. This is because of a very fast inhibition of VSG gene transcription which occurs as soon as the temperature is lowered. We report that this effect is probably not controlled at the level of transcription initiation, since the beginning of the VSG gene expression site, about 45 kilobases upstream from the antigen gene, remains transcribed in procyclic forms. The permanent activity of the promoter readily accounts for the systematic reappearance, upon return to the bloodstream form after cyclical transmission, of the antigen type present before passage to the tsetse fly. The abortive transcription of the VSG gene expression site appears linked to RNA processing abnormalities. Such posttranscriptional controls may allow the modulation of gene expression in a genome organized in large multigenic transcription units.

scholarly journals A similar gene is shared by both the variant surface glycoprotein and procyclin gene transcription units of Trypanosoma brucei

1991 ◽  
Vol 11 (3) ◽  
pp. 1473-1479
Author(s):  
M Berberof ◽  
A Pays ◽  
E Pays
Keyword(s):  
Gene Expression ◽  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Gene Transcription ◽  
Transcription Unit ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Polycistronic Transcription ◽  
Expression Site ◽  
Similar Gene

The genes for the variant surface glycoprotein (VSG) and procyclin are expressed in a mutually exclusive manner during the life cycle of Trypanosoma brucei and synthesize the most abundant mRNAs specific to the bloodstream and procyclic stages of the parasite, respectively. Genes belonging to the polycistronic transcription unit of the VSG gene (expression site-associated genes [ESAGs]) are uniquely expressed in the bloodstream form, but some members of ESAG families (genes related to ESAGs [GRESAGs]) are independently transcribed outside the VSG gene expression site. We report here that a gene related to ESAG 2, GRESAG 2.1, is present and expressed in a procyclin gene transcription unit (PARP A locus), which is polycistronic. Members of the ESAG 2 family are thus present in the two major differentially stage-regulated transcription units of this parasite.

scholarly journals A similar gene is shared by both the variant surface glycoprotein and procyclin gene transcription units of Trypanosoma brucei.

1991 ◽  
Vol 11 (3) ◽  
pp. 1473-1479 ◽  
Author(s):  
M Berberof ◽  
A Pays ◽  
E Pays
Keyword(s):  
Gene Expression ◽  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Gene Transcription ◽  
Transcription Unit ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Polycistronic Transcription ◽  
Expression Site ◽  
Similar Gene

The genes for the variant surface glycoprotein (VSG) and procyclin are expressed in a mutually exclusive manner during the life cycle of Trypanosoma brucei and synthesize the most abundant mRNAs specific to the bloodstream and procyclic stages of the parasite, respectively. Genes belonging to the polycistronic transcription unit of the VSG gene (expression site-associated genes [ESAGs]) are uniquely expressed in the bloodstream form, but some members of ESAG families (genes related to ESAGs [GRESAGs]) are independently transcribed outside the VSG gene expression site. We report here that a gene related to ESAG 2, GRESAG 2.1, is present and expressed in a procyclin gene transcription unit (PARP A locus), which is polycistronic. Members of the ESAG 2 family are thus present in the two major differentially stage-regulated transcription units of this parasite.

A gene from the variant surface glycoprotein expression site encodes one of several transmembrane adenylate cyclases located on the flagellum of Trypanosoma brucei

1992 ◽  
Vol 12 (3) ◽  
pp. 1218-1225
Author(s):  
P Paindavoine ◽  
S Rolin ◽  
S Van Assel ◽  
M Geuskens ◽  
J C Jauniaux ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Trypanosoma Brucei ◽  
Membrane Fraction ◽  
Transcription Unit ◽  
Bloodstream Form ◽  
Surface Glycoprotein ◽  
Yeast Cells ◽  
Variant Surface Glycoprotein ◽  
Polycistronic Transcription ◽  
Expression Site

The bloodstream form of Trypanosoma brucei contains transcripts of at least four genes showing partial sequence homology to the genes for eucaryotic adenylate and guanylate cyclases (S. Alexandre, P. Paindavoine, P. Tebabi, A. Pays, S. Halleux, M. Steinert, and E. Pays, Mol. Biochem. Parasitol. 43:279-288, 1990). One of these genes, termed ESAG 4, belongs to the polycistronic transcription unit of the variant surface glycoprotein (VSG) gene. Whereas ESAG 4 is transcribed only in the bloodstream form of the parasite, the three other genes, GRESAG 4.1, 4.2, and 4.3, are also expressed in procyclic (insect) forms. These genes differ primarily in a region presumed to encode a large extracellular domain. We show here that ESAG 4-related glycoproteins of about 150 kDa can be found in the trypanosome membrane, that they are detected, by light and electron gold immunocytochemistry, only at the surface of the flagellum, and that the products of at least two of these genes, ESAG 4 and GRESAG 4.1, can complement a Saccharomyces cerevisiae mutant for adenylate cyclase. The recombinant cyclases are associated with the yeast membrane fraction and differ with respect to their activation by calcium: while the GRESAG 4.1 and yeast cyclases are inhibited by calcium, the ESAG 4 cyclase is stimulated. ESAG 4 thus most probably encodes the calcium-activated cyclase that has been found to be expressed only in the bloodstream form of T. brucei (S. Rolin, S. Halleux, J. Van Sande, J. E. Dumont, E. Pays, and M. Steinert. Exp. Parasitol. 71:350-352, 1990). Our data suggest that the trypanosome cyclases are not properly regulated in yeast cells.

Expression of a retroposon-like sequence upstream of the putative Trypanosoma brucei variant surface glycoprotein gene expression site promoter

1993 ◽  
Vol 13 (11) ◽  
pp. 7036-7044
Author(s):  
M J Lodes ◽  
B L Smiley ◽  
A W Stadnyk ◽  
J L Bennett ◽  
P J Myler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Copy Number ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Putative Promoter ◽  
Glycoprotein Gene ◽  
Active Expression ◽  
Expression Site ◽  
Total Copy Number

We have cloned the region spanning the putative promoter from two variant surface glycoprotein gene expression sites that are at each end of chromosome M4 of Trypanosoma brucei IsTat 7. Both expression sites contain a retroposon-like sequence (ESR) pseudogene whose 3' end is approximately 30 bp upstream of the putative expression site promoter. The ESRs from both expression sites share considerable sequence homology and are related to LINE-like elements, especially the T. brucei ingi retroposon. Other ESRs are located on large, but not intermediate or mini-, chromosomes in the IsTaR 1 serodeme, and the total copy number is 10 to 20, similar to that estimated for variant surface glycoprotein expression sites. No DNA rearrangements in the vicinity of the ESR and putative expression site promoter were detected following antigenic switches in the IsTaR 1 serodeme. ESR transcripts are present in bloodstream, but not procyclic, forms. Variation in transcript size and sequence between bloodstream variant antigenic types implies that only the ESR from the active expression site is transcribed. This pattern of expression reflects that of sequences downstream of the putative expression site promoter, suggesting that the region of coordinately controlled expression extends upstream of this promoter.

scholarly journals Variable Surface Glycoprotein from Trypanosoma brucei Undergoes Cleavage by Matrix Metalloproteinases: An in silico Approach

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 178
Author(s):  
Cláudia Jassica Gonçalves Moreno ◽  
Taffarel Torres ◽  
Marcelo Sousa Silva
Keyword(s):  
Matrix Metalloproteinases ◽  
Trypanosoma Brucei ◽  
Cleavage Site ◽  
Surface Protein ◽  
Matrix Metalloproteases ◽  
Surface Glycoprotein ◽  
Mammalian Host ◽  
Variable Surface Glycoprotein ◽  
Biological Studies ◽  
Variable Surface

In order to survive as extracellular parasites in the mammalian host environment, Trypanosoma brucei has developed efficient mechanisms of immune system evasion, which include the abundant expression of a variable surface glycoprotein (VSG) coat. VSGs are anchored in the parasite membrane by covalent C-terminal binding to glycosylphosphatidylinositol and may be periodically removed by a phospholipase C (PLC) and a major surface protein (TbMSP). VSG molecules show extraordinary antigenic diversity and a comparative analysis of protein sequences suggests that conserved elements may be a suitable target against African trypanosomiasis. However, the cleavage mechanisms of these molecules remain unclear. Moreover, in protozoan infections, including those caused by Trypanosoma brucei, it is possible to observe an increased expression of the matrix metalloproteinases (MMPs). To address the cleavage mechanism of VSGs, the PROSPER server was used for the identification of VSG sequence cleavage sites. After data compilation, it was observed that 64 VSG consensus sequences showed a high conservation of hydrophobic residues, such as valine (V), methionine (M), leucine (L) and isoleucine (I) in the fifth position—the exact location of the cleavage site. In addition, the PROSPER server identified conserved cleavage site portions of VSG proteins recognized by three matrix metalloproteases (gelatinases: MMP-2, MMP-3 and MMP-9). However, further biological studies are needed in order to analyze and confirm this prediction.

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