Identification of a developmentally regulated iron superoxide dismutase of Trypanosoma brucei

An iron superoxide dismutase (FeSOD) gene of the protozoan parasite Trypanosoma brucei has been cloned and its gene product functionally characterized. The gene encodes a protein of 198 residues which shows 80% identity with FeSODs from other trypanosomatids. Inhibitor studies with purified recombinant FeSOD expressed in Escherichia coli confirmed that the enzyme is an iron-containing SOD. The FeSOD is developmentally regulated in the parasite, expression being lowest in the cell-cycle-arrested, short stumpy bloodstream forms. Differential expression of the FeSOD protein contrasts with only minor quantitative changes in the FeSOD mRNA, indicating post-transcriptional regulation of the enzyme. As the level of FeSOD increases during differentiation of cell-cycle-arrested short stumpy into dividing procyclic forms, it is suggested that the enzyme is only required in proliferating stages of the parasite for the elimination of superoxide radicals which are released during the generation of the iron-tyrosyl free-radical centre in the small subunit of ribonucleotide reductase.

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Identification of a developmentally regulated iron superoxide dismutase of Trypanosoma brucei

Biochemical Journal ◽

10.1042/0264-6021:3600173 ◽

2001 ◽

Vol 360 (1) ◽

pp. 173 ◽

Cited By ~ 6

Author(s):

Mostafa KABIRI ◽

Dietmar STEVERDING

Keyword(s):

Superoxide Dismutase ◽

Trypanosoma Brucei ◽

Developmentally Regulated ◽

Iron Superoxide Dismutase

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Polo-like kinase is required for Golgi and bilobe biogenesis in Trypanosoma brucei

The Journal of Cell Biology ◽

10.1083/jcb.200708082 ◽

2008 ◽

Vol 181 (3) ◽

pp. 431-438 ◽

Cited By ~ 47

Author(s):

Christopher L. de Graffenried ◽

Helen H. Ho ◽

Graham Warren

Keyword(s):

Cell Cycle ◽

Endoplasmic Reticulum ◽

Trypanosoma Brucei ◽

Protozoan Parasite ◽

Controlled Assembly

A bilobed structure marked by TbCentrin2 regulates Golgi duplication in the protozoan parasite Trypanosoma brucei. This structure must itself duplicate during the cell cycle for Golgi inheritance to proceed normally. We show here that duplication of the bilobed structure is dependent on the single polo-like kinase (PLK) homologue in T. brucei (TbPLK). Depletion of TbPLK leads to malformed bilobed structures, which is consistent with an inhibition of duplication and an increase in the number of dispersed Golgi structures with associated endoplasmic reticulum exit sites. These data suggest that the bilobe may act as a scaffold for the controlled assembly of the duplicating Golgi.

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A role for Sar1 and ARF1 GTPases during Golgi biogenesis in the protozoan parasite Trypanosoma brucei

Molecular Biology of the Cell ◽

10.1091/mbc.e17-03-0151 ◽

2017 ◽

Vol 28 (13) ◽

pp. 1782-1791 ◽

Cited By ~ 2

Author(s):

Sevil Yavuz ◽

Graham Warren

Keyword(s):

Cell Cycle ◽

Trypanosoma Brucei ◽

Protozoan Parasite ◽

Small Gtpases ◽

Intact Cells ◽

Golgi Stack ◽

Daughter Cells ◽

Photoactivatable Gfp

A single Golgi stack is duplicated and partitioned into two daughter cells during the cell cycle of the protozoan parasite Trypanosoma brucei. The source of components required to generate the new Golgi and the mechanism by which it forms are poorly understood. Using photoactivatable GFP, we show that the existing Golgi supplies components directly to the newly forming Golgi in both intact and semipermeabilized cells. The movement of a putative glycosyltransferase, GntB, requires the Sar1 and ARF1 GTPases in intact cells. In addition, we show that transfer of GntB from the existing Golgi to the new Golgi can be recapitulated in semipermeabilized cells and is sensitive to the GTP analogue GTPγS. We suggest that the existing Golgi is a key source of components required to form the new Golgi and that this process is regulated by small GTPases.

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Small-Subunit rRNA Processome Proteins Are Translationally Regulated during Differentiation of Trypanosoma cruzi

Eukaryotic Cell ◽

10.1128/ec.00279-06 ◽

2006 ◽

Vol 6 (2) ◽

pp. 337-345 ◽

Cited By ~ 25

Author(s):

Sheila Cristina Nardelli ◽

Andréa Rodrigues Ávila ◽

Aline Freund ◽

Maria Cristina Motta ◽

Lauro Manhães ◽

...

Keyword(s):

Cell Cycle ◽

Trypanosoma Cruzi ◽

Sucrose Gradient ◽

Protozoan Parasite ◽

Small Subunit ◽

Small Subunit Rrna ◽

Translation Elongation ◽

Metacyclic Trypomastigotes ◽

Ssu Processome ◽

Polysome Fraction

ABSTRACT We used differential display to select genes differentially expressed during differentiation of epimastigotes into metacyclic trypomastigotes in the protozoan parasite Trypanosoma cruzi. One of the selected clones had a sequence similar to that of the small-subunit (SSU) processome protein Sof1p, which is involved in rRNA processing. The corresponding T. cruzi protein, TcSof1, displayed a nuclear localization and is downregulated during metacyclogenesis. Heterologous RNA interference assays showed that depletion of this protein impaired growth but did not affect progression through the cell cycle, suggesting that ribosome synthesis regulation and the cell cycle are uncoupled in this parasite. Quantitative PCR (qPCR) assays of several SSU processome-specific genes in T. cruzi also showed that most of them were regulated posttranscriptionally. This process involves the accumulation of mRNA in the polysome fraction of metacyclic trypomastigotes, where TcSof1 cannot be detected. Metacyclic trypomastigote polysomes were purified and separated by sucrose gradient sedimentation. Northern blot analysis of the sucrose gradient fractions showed the association of TcSof1 mRNA with polysomes, confirming the qPCR data. The results suggest that the mechanism of regulation involves the blocking of translation elongation and/or termination.

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Golgi duplication in Trypanosoma brucei

The Journal of Cell Biology ◽

10.1083/jcb.200311076 ◽

2004 ◽

Vol 165 (3) ◽

pp. 313-321 ◽

Cited By ~ 109

Author(s):

Cynthia Y. He ◽

Helen H. Ho ◽

Joerg Malsam ◽

Cecile Chalouni ◽

Christopher M. West ◽

...

Keyword(s):

Cell Cycle ◽

Endoplasmic Reticulum ◽

Golgi Apparatus ◽

Trypanosoma Brucei ◽

Basal Body ◽

Time Course ◽

Matrix Protein ◽

De Novo ◽

Protozoan Parasite ◽

Er Export

Duplication of the single Golgi apparatus in the protozoan parasite Trypanosoma brucei has been followed by tagging a putative Golgi enzyme and a matrix protein with variants of GFP. Video microscopy shows that the new Golgi appears de novo, near to the old Golgi, about two hours into the cell cycle and grows over a two-hour period until it is the same size as the old Golgi. Duplication of the endoplasmic reticulum (ER) export site follows exactly the same time course. Photobleaching experiments show that the new Golgi is not the exclusive product of the new ER export site. Rather, it is supplied, at least in part, by material directly from the old Golgi. Pharmacological experiments show that the site of the new Golgi and ER export is determined by the location of the new basal body.

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Characterization of the sodF gene region of Frankia sp. strain ACN14a and complementation of Escherichia coli sod mutant

Canadian Journal of Microbiology ◽

10.1139/w03-035 ◽

2003 ◽

Vol 49 (4) ◽

pp. 294-300 ◽

Cited By ~ 3

Author(s):

Joëlle Maréchal ◽

Renata Santos ◽

Yasser Hammad ◽

Nicole Alloisio ◽

Anne-Marie Domenach ◽

...

Keyword(s):

Escherichia Coli ◽

Superoxide Dismutase ◽

Root Exudates ◽

Alnus Glutinosa ◽

Triple Mutant ◽

Iron Superoxide Dismutase ◽

E Coli ◽

Its Gene ◽

Tac Promoter ◽

The One

The Frankia sp. strain ACN14a superoxide dismutase SodF was previously shown to be induced in response to Alnus glutinosa root exudates, and its gene was sequenced. We report here the sequence of the 9-kb genomic segment surrounding the sodF gene and further characterize this gene and its product. Nine ORFs coding for various proteins, such as regulators, acetyl-CoA transferases, and a bacterioferritin A next to the sodF gene, were found. Northern blot analysis showed that the sodF gene was expressed as a major 1-kb transcript, which indicates that it has its own promoter. The sodF gene strongly complemented an Escherichia coli triple mutant (sodA sodB recA), restoring aerobic growth when the gene was expressed from the synthetic tac promoter but when expressed from its own promoter showed only slight rescue, suggesting that it was poorly recognized by the E. coli RNA polymerase. It is noteworthy that this is the first time that a Frankia gene has been reported to complement an E. coli mutant. The superoxide dismutase activity of the protein was inactivated by hydrogen peroxide, indicating that the metal ligand is iron, which is supported by analysis of the protein sequence. Thus, the SodF protein induced in Frankia by root exudates is an iron-containing enzyme similar to the one present in the nodules.Key words: Frankia, iron superoxide dismutase, sodF, E. coli complementation.

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